Comparing Ventilator-displayed Rapid Shallow Breathing Index Values Versus Standard Measurement Techniques: A Bench Study

Comparing Ventilator-displayed Rapid Shallow Breathing Index Values Versus Standard Measurement Techniques: A Bench Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparing Ventilator-displayed Rapid Shallow Breathing Index Values Versus Standard Measurement Techniques: A Bench Study Hsin-Hsien Li, Kai-Tien Chang, I-Hsin Lin, Yu-Rong Hsu, Jennifer Shuangfan Wu, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7339226/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: The rapid shallow breathing index (RSBI) is a key indicator for assessing weaning readiness, based on simple and non-invasive measurements. However, the standard method requires patient cooperation, specialized equipment, and patient disconnection from the ventilator, which increases the risk of aerosol dispersion. Many modern ventilators address these limitations by displaying RSBI values directly on the screen; however, the accuracy and reliability of the displayed data have yet to be confirmed. This study compared the accuracy of RSBI values obtained from ventilators with the gold standard method using a lung simulator. Methods: This bench study was conducted using a manikin equipped with a lung simulator designed to mimic spontaneous breathing under preset resistance and compliance (normal, obstructive, restrictive) conditions. Two ventilators were tested under three modes: continuous positive airway pressure (CPAP) at 0 and 5 cmH 2 O, and pressure support ventilation (PSV) at 5 cmH 2 O combined with positive end-expiratory pressure (PEEP) of 5 cmH 2 O. RSBI values displayed by the ventilators were recorded at 0, 15, 30, 45, and 60 seconds. The standard handheld method required disconnection of the ventilator to measure the minute volume (MV), from which tidal Volume (V T ) and RSBI were calculated. Results: In PSV mode, the average RSBI value was significantly lower than that measured using the spirometer; however, no difference was detected in CPAP mode. No significant differences in mean RSBI values were detected across different flow trigger settings, irrespective of the operating mode. The choice of flow trigger was not correlated with airway pressure, RSBI, MV, V T , respiratory rate, PSV level, or PEEP. Bland-Altman plots revealed good agreement between ventilator-measured RSBI values and those obtained using a handheld spirometer RSBI in CPAP mode. Conclusions: RSBI values presented by the ventilator in PSV mode were significantly lower than those obtained using a handheld device. No discrepancies were observed in CPAP mode, and flow trigger settings did not have a significant effect on RSBI measurements. Clinicians should be cautious of the deviation in RSBI values captured in PSV mode. Our findings suggest that CPAP mode may be a more suitable option for assessing weaning readiness. Rapid shallow breathing index Flow trigger Ventilator Spirometer Correlation Consistency Figures Figure 1 Figure 2 Figure 3 Introduction Weaning critically ill patients from mechanical ventilation remains a significant challenge, requiring a delicate balance between the risk of premature extubation failure and avoiding unnecessary prolonged mechanical ventilation. The rapid shallow breathing index (RSBI) is used by clinicians to assess the probability of successful liberation from mechanical ventilation as a guide to decision-making during the weaning process [1]. The threshold defined by Yang and Tobin in 1991 (≤ 105 breaths/min/L) achieved 97% sensitivity, 64% specificity, 78% positive predictive value, and 95% negative predictive value [2]. Although meta-analyses have confirmed that SBT is the most effective predictor of successful extubation [3], studies showed that up to 13% of patients who pass SBT may still require reintubation [4]. In real practice, RSBI is assessed after an SBT to help respiratory therapists make informed and cautious extubation decisions. Spontaneous breathing is generally assessed according to respiratory frequency and tidal volume (V T ) through an endotracheal tube, based on readings obtained using a handheld Wright spirometer during the first minute after disconnecting the patient from the ventilator [2]. While this method is considered the gold standard, it requires patient cooperation, specialized equipment, and disconnection from the ventilator, which increases the risk of aerosol dispersion and the potential spread of hospital-acquired acute respiratory infections [5]. To address these limitations, intensive care unit (ICU) ventilators have been developed to calculate RSBI values without disconnecting the patient and then display the results directly on the ventilator screen [6, 7]. Many current ICU ventilators can display the RSBI values on these systems, which are calculated on a breath-to-breath basis, depending on the algorithm. Numerous studies have assessed the accuracy of RSBI measurements, particularly those obtained in spontaneous breathing modes, such as pressure support ventilation (PSV), continuous positive airway pressure (CPAP), and T-piece configurations [6–11]. RSBI measurements are relatively unaffected by the time at which they are taken or by changes in the fraction of inspired oxygen [10,11]. Desai et al. proposed using CPAP 5 cmH 2 O measurements obtained through the ventilator as an alternative to standard RSBI measurements. They observed that those values were lower than those obtained using a handheld spirometer and identified base flow variables that can significantly affect RSBI estimates [7]. Some experts have hypothesized that the higher pressure delivered by the base flow compensates for the resistance of the tubing, leading to significantly lower RSBI measurements [6]. Researchers have also reported discrepancies in RSBI values attributed to the patient’s underlying condition. Moreover, the administration of 5 cmH 2 O positive end-expiratory pressure (PEEP) has been shown to affect RSBI values, particularly after cardiac surgery [10]. Given the limitations of spirometer availability, the risk of aerosol dispersion, and infection control concerns, it is crucial to identify ventilator parameters that yield RSBI values comparable to those obtained with a spirometer. This study aimed to evaluate the accuracy of ventilator-displayed RSBI values against the gold standard using a lung simulator. This study also sought to determine whether ventilatory settings affect RSBI values. Materials and methods Study design This laboratory study was conducted between September and November 2024 at the Respiratory Therapy Laboratory of Chang Gung University in Taoyuan, Taiwan. Throughout the experiments, room temperature was maintained at 25°C with an atmospheric pressure of 760 mmHg. The gas was held in the Ambient Temperature Pressure Saturated (ATPS) state. The laboratory is equipped with a stable medical gas system supplying oxygen at 50 ± 5 pounds per square inch (PSI) and air at 50 ± 5 PSI. A lung simulator was used to mimic spontaneous breathing in patients. Three lung conditions were simulated to replicate the pulmonary characteristics associated with obstructive lung disease, restrictive lung disease, and normal lungs. ASL 5000 simulation To replicate real-world clinical scenarios involving patient intubation, this study employed an ASL 5000 lung simulator (IngMar Medical, Pittsburgh, Pennsylvania, U.S.A.) connected to a manikin via a 7.5 mm endotracheal tube. This system features a computer-controlled piston that displaces gas at preset volumes to mimic spontaneous breathing. The movement of the piston is governed by equations of motion based on the respiratory system, allowing precise adjustments of airway resistance (Raw), respiratory system compliance (Crs), respiratory rate (RR), and inspiratory time (Ti), thereby simulating the effort of inspiratory muscles (Pmus) under various mechanical conditions. Based on a review of the literature [12] and manufacturer guidelines [13], this study focused on three distinct respiratory patterns: Normal: Raw = 13 cmH 2 O/L/s; Crs = 50 mL/cmH 2 O; Pmus = 13 cmH 2 O; RR = 15 ± 3 breaths/min; Ti = 0.8 s. Obstructive: Raw = 21 cmH 2 O/L/s; Crs = 60 mL/cmH 2 O; Pmus = 14 cmH 2 O; RR = 18 ± 3 breaths/min; Ti = 1s. Restrictive: Raw = 10 cmH 2 O/L/s; Crs = 25 mL/cmH 2 O; Pmus = 15 cmH 2 O; RR = 30 ± 3 breaths/min; Ti = 0.8 s. Ventilator settings and monitoring This study conducted tests using two ventilators: Hamilton Medical G5 (Switzerland) and Dräger V300 (Germany). Ventilator modes included CPAP (0 and 5 cmH 2 O), PSV (5 cmH 2 O), and PEEP (5 cmH 2 O). The impact of flow trigger settings on ventilator-measured values was assessed at 5 flow rates: 0.5, 2, 4, 6, and 8 L/min. Airway pressure was recorded using an electronic manometer (GB 60, GaleMed, Yilan, Taiwan) positioned at the Y-piece of the ventilator circuit. Measuring of RSBI RSBI values were obtained from two ventilator readings or a handheld spirometer (Haloscale, Ferraris Medical Inc., Louisville, Colorado, U.S.A.). Measurements were obtained at 0, 15, 30, 45, and 60 seconds under three spontaneous modes: CPAP (5 cmH 2 O), CPAP (0 cmH 2 O), and PSV (5 cmH 2 O) with PEEP (5 cmH 2 O). A one-minute stabilization period was allowed after each adjustment of ventilator settings before measurements were recorded. The G5 ventilator displayed RSBI values (denoted as RSB) in real-time on its screen. This value was calculated as the total respiratory rate (fTotal) divided by exhaled tidal volume (VTE), provided that at least 80% of the breaths during the last 25 cycles were spontaneous in adult ventilation mode. The V300 ventilator also displayed RSBI values (denoted as RSB) in real-time on the ventilator screen. This value was calculated as the spontaneous respiratory rate (RRspon) divided by spontaneous tidal volume (VTspon). When using the handheld device, measurements were obtained by disconnecting the ventilator to record MV. V T was then calculated by dividing MV by the RR, and RSBI was determined by dividing RR by V T . Statistical Analysis Continuous variables are presented as mean ± standard deviation. The mean flow trigger settings as well as the mean RSBI, V T , RR, and MV values were compared across operating modes and between the two ventilators using ANOVA or the Kruskal-Wallis test, followed by post hoc analysis where applicable. Analysis was performed using Prism GraphPad 8.0 (GraphPad Software, Boston, Massachusetts, U.S.A.) with a p -value < 0.05 considered statistically significant. Pearson or Spearman’s correlation was used to assess the relationship between airway pressure, flow trigger settings, and other parameters using SPSS 26.0 (IBM, U.S.A.). Correlation coefficients with a 95% confidence interval were reported, and p < 0.05 was considered statistically significant. Results Fig. 1 presents a schematic illustration of the experiment setup. A total of 480 measurements were collected, with each measurement obtained using all 4 methods (PSV 5/5 cm H 2 O, CPAP 5 cm H 2 O, CPCP 0 cm H 2 O, handheld spirometer) across the three lung simulations. Data from the three breathing patterns were pooled for analysis. Notable differences were observed between the mean RSBI, V T , RR, and MV values obtained using the two ventilators and those measured using the handheld spirometer (Table 1). In PSV mode, the mean RSBI of the V300 ventilator (41.61 ± 18.64 vs. 59.73 ± 24, p = 0.003) was significantly lower than the handheld values, while the mean V T (500.47 ± 79.91 vs. 366.58 ± 37.16, p < 0.001) and mean MV (9.87 ± 2.01 vs. 7.57 ± 1.84, p < 0.001) were significantly higher. Similarly, the mean RSBI of the G5 ventilator in PSV mode (43.92 ± 20.86 vs. 59.73 ± 24, p < 0.045) was significantly lower than the handheld values, while the mean V T (508.33 ± 82.22 vs. 366.58 ± 37.16, p < 0.001), and mean MV (10.06 ± 1.53 vs. 7.57 ± 1.84, p < 0.001) were significantly higher. In CPAP 5 and 0 cm H 2 O modes, no significant differences were observed between the RSBI, V T , RR, and MV values from ventilators versus handheld devices. Note that RR did not exhibit significant differences under any of the tested conditions. Subsequent analysis of RSBI values as a function of trigger flow settings across ventilatory modes revealed further insights. The flow trigger was set at 0.5, 2, 4, 6, and 8 L/min. Mean RSBI values were consistent across both ventilators and showed no significant differences across trigger flow settings, irrespective of ventilatory mode (Table 2). To further investigate the impact of the flow trigger, we examined its correlation with other parameters. No significant correlations were identified between flow trigger settings and RSBI, MV, V T , RR, PSV level, or PEEP (Tables 3A and 3B). Tables 3A and 3B list the correlations between airway pressure and other parameters. Regardless of which ventilator was used (V300 or G5), significant correlations were observed between airway pressure and the following parameters: RSBI (r = -0.357, p < 0.05 ; r = -0.441, p < 0.01), MV (r = 0.339, p < 0.05 ; r = 0.649, p < 0.01), V T (r = 0.638, p < 0.01; r = 0.654, p < 0.01), PSV level (r = 0.768, p < 0.001 ; r = 0.817, p < 0.01), and PEEP (r = 0.898, p < 0.01 ; r = 0.817, p < 0.01). No significant correlation was observed between airway pressure and RR. Regardless of which ventilator was used, RSBI was significantly correlated with the following parameters: MV (r = 0.578, p < 0.01; r = 0.301, p < 0.01), V T (r = -0.730, p < 0.01 ; r = -0.896, p < 0.01), and RR (r = 0.946, p < 0.01; r = 0.730, p < 0.01). RSBI was significantly correlated with PSV when using the V300 ventilator (r = -0.367, p < 0.05). Interactions were also observed among parameters, including MV, V T , RR, PSV level, and PEEP. Consistency between ventilator measurements and the standard handheld method was assessed in terms of mean RSBI values recorded from 0 to 60 seconds. The V300 ventilator demonstrated good agreement with the handheld spirometer when used in CPAP 5 or 0 cmH 2 O mode. In CPAP mode at 5 cmH 2 O, the bias was 3.654 and precision was 4.507 (range: -5.179 to 12.49) (Fig. 2A). In CPAP mode at 0 cmH 2 O, the bias was 3.921 and precision was 2.46 (range: -0.899 to 8.742) (Fig. 2B). The mean difference in RSBI values between the G5 ventilator and spirometer was as follows: CPAP 5 cmH 2 O (-1.132; range: -12.65 to 10.3) (Fig. 2C) and CPAP 0 cmH 2 O (-4.519; range: -17.19 to 8.152) (Fig. 2D). Correlation analysis using Spearman’s correlation coefficient revealed a strong, statistically significant relationship between the RSBI value obtained from the spirometer and the average RSBI value from 0 to 60 seconds in the CPAP mode of both ventilators. The Spearman’s correlation coefficients were 0.846, 0.966, 0.900, and 0.869, respectively (Fig. 3A, 3C, 3E, 3G). Similarly, a high correlation was observed between the RSBI value from the handheld spirometer and the RSBI value at 60 seconds (r = 0.832, 0.904, 0.845, 0.876; all p < 0.001) (Fig. 3B, 3D, 3F, 3H). Discussion To the best of our knowledge, this is the first study to use lung simulation to compare the accuracy of RSBI values measured by a ventilator versus those obtained using a handheld spirometer. In PSV mode, the average RSBI values were significantly lower than those measured using the spirometer; however, no differences were detected in CPAP mode. No significant differences in mean RSBI values were detected across flow trigger settings, irrespective of the operating mode. The choice of flow trigger was not correlated with airway pressure, RSBI, MV, V T , RR, PSV level, or PEEP. When patients enter the weaning process, SBTs can be conducted using either the PSV method or T-piece method [14]. Numerous studies have assessed the accuracy and validity of alternative RSBI measurement methods during SBT. It has been reported that the RSBI values during PSV at 5 cmH 2 O are lower than those using the T-piece method [11]. Similarly, our RSBI values recorded in PSV mode were significantly lower than those derived using a handheld spirometer. This can be partially attributed to higher V T and MV without RR variation. We theorize that higher pressure support facilitates the delivery of greater tidal volumes, thereby reducing the RSBI ratio. PSV is more effective than the T-piece method in overcoming the resistance created by the endotracheal tube and ventilator circuit [15] to reduce respiratory effort [16]. However, the compensation for resistance from the endotracheal tube is absent when measurements are obtained using a spirometer. Consequently, PSV reduces the calculated RSBI value, which may lead to an overestimation of the patient's readiness to be weaned off ventilatory support. At present, the effect of PEEP on RSBI remains a topic of debate. One study reported that CPAP at 5 cm H 2 O influenced RSBI assessments in post-cardiac surgery patients [10]. Another study on 60 mechanically ventilated patients reported no difference between values obtained using a Wright spirometer and those obtained using a ventilator with the CPAP set to zero [8]. In the current study, RSBI values measured in CPAP at 0 or 5 cmH 2 O were essentially identical to those obtained using a spirometer, probably due to the relatively low pressure in CPAP mode. Previous studies have reported that RSBI measurements obtained through the ventilator were affected by flow-by mode. However, this issue remains unclear. Patel et al. reported no difference between RSBI values based on a handheld spirometer and those obtained through the ventilator under CPAP 0 or PS 0 cmH 2 O without flow-by [8]. Kheir et al. reported that RSBI values measured through the ventilator without a flow trigger were higher than those obtained using a digital spirometer [6]. Those researchers posited that the pressure provided by the base flow not only compensated for the resistance of the tubing but also reduced of the workload imposed by breathing, thereby lowering the RSBI value. This study obtained contradictory findings. First, modern ventilators provide continuous base flow (e.g., 2 L/min), regardless of whether the user sets the flow trigger or pressure trigger to zero. This suggests that flow is always present in spontaneous modes, regardless of the settings. Second, every ventilator has its own flow trigger range. When assessing the impact of flow trigger settings, we found that the actual flow adhered to the rule of maintaining a base flow 2 L/min above the zero-flow trigger baseline. The base flow rates of the V300 ventilator were set at 2, 4, 6, 8, and 10 L/min. The G5 ventilator followed a doubling rule, generating base flow rates of 2, 4, 8, 12, and 16 L/min. Our analysis revealed no significant variations in RSBI values under base flow rates of 0.5, 2, 4, 6, or 8 L/min. Moreover, no correlations were detected between flow trigger settings and other parameters. Third, no correlation was detected between airway pressure and the flow trigger. In flow trigger mode, the delivery of base flow generates pressure; however, the flow trigger itself has no direct influence on pressure in the airway. Moreover, our analysis revealed that airway pressure is strongly correlated with PSV levels and PEEP, which suggests the contribution of these factors in compensating for the resistance of the tubing, thereby reducing RSBI values. Using the average of five ventilator-displayed RSBI values over a period of 0–60 s yielded a stronger correlation than did interval measurements at 0–15, 0–30, and 0–45 s [9]. In the current study, ventilator-displayed RSBI was averaged across five time points (0, 15, 30, 45, and 60s) under three different lung conditions to enhance clinical applicability. This study also addressed possible interactions among ventilator parameters to strengthen the power of this analysis. Our findings confirmed that RSBI values in CPAP mode were highly consistent with those measured using the spirometer method, aligning with previous clinical studies [9]. It is important to consider that ventilator-displayed RSBI values are based on an accumulation of breaths over the preceding seconds rather than a single breath. Our results also revealed a strong correlation between RSBI values displayed at 60 seconds and those based on manual measurements using a handheld spirometer, which suggests that consistent and reliable results can be obtained from single-point measurements. The ability to assess the patient’s condition based on a single ventilator-displayed RSBI value would be convenient for respiratory therapists in real-world clinical applications. This study was subject to several limitations that should be considered when interpreting our findings. First, this bench study was based on a lung model rather than actual patients. Our findings provide valuable operational insights for clinicians; however, this research lacked data related to patient prognosis or extubation outcomes, which limits the ability to extrapolate the findings to predict weaning success rates. Second, the study examined only two ventilators, both of which were servo-valve devices with similar base flow levels. It is possible that different ventilator designs would provide different results. Third, only flow trigger mode was used to activate the ventilators; pressure trigger mode was not tested or included in the analysis. It is important to note that modern ventilators maintain a constant base flow to sense the patient’s breathing effort, regardless of whether flow or pressure triggers are used. Future studies should focus on replicating and validating these findings in clinical settings with actual patients to assess their applicability and impact on clinical outcomes. Conclusions This study compared the accuracy of RSBI values obtained from ventilators with the gold standard method using a lung simulator designed to mimic spontaneous breathing under normal, obstructive, and restrictive conditions. Two ventilators were tested under three modes: CPAP at 0 cmH 2 O; CPAP at 5 cmH 2 O, and PSV at 5 cmH 2 O with PEEP of 5 cmH 2 O. RSBI values displayed by the ventilators were recorded at 0, 15, 30, 45, and 60 seconds. RSBI values displayed by the ventilator in PSV mode were significantly lower than those obtained using a handheld device. No discrepancies were observed in CPAP mode, and flow trigger settings did not have a significant effect on RSBI measurements. Clinicians should be cautious of the deviation in RSBI values captured in PSV mode. Our findings suggest that CPAP mode may be a more suitable option for assessing weaning readiness. Future research will be required to verify these findings in clinical practice. Abbreviations CPAP Continuous positive airway pressure Crs Compliance ICU Intensive care units PEEP Positive and end-expiratory pressure PSI Pounds per square inch PSV Pressure support ventilation Raw resistance RSBI Rapid shallow breathing index SBT Spontaneous breathing trials Declarations All authors declared no conflicts of interest. Acknowledgments We thank the Department of Respiratory Therapy at Chang Gung University for assistance during the study. Supplementary Materials Not applicable. Authors’ contribution H.-H. Li, K.-T. Chang, I.-H. Lin, Y.-R. Hsu, and J.-S. Wu conceived and designed research; H.-H. Li and L.-C. Chiu drafted the manuscript; H.-H. Li and L.-C. Chiu edited and revised the manuscript. H.-H. Li, K.-T. Chang, I.-H. Lin, Y.-R. Hsu, and J.-S. Wu prepared the figures. All authors interpreted the results and approved the final version of the manuscript prior to submission. Funding This study was supported by funding from the student research project at Chang Gung University. Availability of data and materials Data supporting the findings of this study are available from the corresponding author upon reasonable request. Ethics approval and consent to participate Not applicable. Competing interests All authors declare that no conflict of interest. Consent for publication Not applicable. References Karthika M, Al Enezi FA, Pillai LV, Arabi YM. Rapid shallow breathing index. Ann Thorac Med. 2016;11(3):167-76. Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med. 1991;324(21):1445-50. Trivedi V, Chaudhuri D, Jinah R, Piticaru J, Agarwal A, Liu K, et al. The Usefulness of the Rapid Shallow Breathing Index in Predicting Successful Extubation: A Systematic Review and Meta-analysis. Chest. 2022;161(1):97-111. Boles JM, Bion J, Connors A, Herridge M, Marsh B, Melot C, et al. 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Tables Table 1 RSBI, V T , RR, MV values averaged across 5 time points (0, 15, 30, 45, and 60 seconds) Handheld V300 G5 PSV 5/5 cmH 2 O CPAP 5 cmH 2 O CPAP 0 cmH 2 O P 1 P 2 P 3 PSV 5/5 cmH 2 O CPAP 5 cmH 2 O CPAP 0 cmH 2 O P 1 P 2 P 3 RSBI (cycle/min/L) 59.73 ± 24 41.61 ± 18.64 55.16 ± 22.84 54.89 ± 23.53 0.003 0.821 0.794 43.92 ± 20.86 59.95 ± 27.66 63.33 ± 28.29 0.045 1.0 0.935 V T (ml) 366.58 ± 37.16 500.47 ± 79.91 373.32 ± 57.37 374.92 ± 53.11 < 0.001 0.969 0.943 508.33 ± 82.22 369.09 ± 56.01 352.05 ± 53.88 < 0.001 0.998 0.765 RR (cycle/min) 21.17 ± 6.75 20.65 ± 6.65 20.77 ± 6.65 20.79 ± 6.54 0.988 0.995 0.995 20.75 ± 6.55 20.67 ± 6.54 20.95 ± 6.42 0.993 0.989 0.999 MV (L) 7.57 ± 1.84 9.87 ± 2.01 7.46 ± 1.62 7.37 ± 1.51 < 0.001 0.993 0.965 10.06 ± 1.53 7.36 ± 1.26 6.97 ± 1.22 < 0.001 0.92 0.275 CPAP, continuous positive airway pressure; MV, minute volume; PEEP, positive and end-expiratory pressure; PSV, pressure support ventilation; RR, respiratory rate; RSBI, rapid shallow breathing index; V T , tidal volume All values are expressed as mean ± standard deviation P 1 Comparing handheld vs. ventilator in PSV mode 5 cmH 2 O with PEEP 5 cmH 2 O P 2 Comparing handheld vs. ventilator in CPAP mode 5 cmH 2 O P 3 Comparing handheld vs. ventilator in CPAP mode 0 cmH 2 O Table 2 RSBI values based on flow trigger settings for the two ventilators. A. V300 0.5 L/min 2 L/min 4 L/min 6 L/min 8 L/min p PSV 5/5 cm H 2 O 43.20 ± 22.16 45.53 ± 22.27 41.93 ± 20.9 43.53 ± 23.57 43.93 ± 21.12 0.995 CPAP 5 cm H 2 O 59.40 ± 30.88 61.87 ± 31.58 58.4 ± 28.13 57.93 ± 27.42 58 ± 27.52 0.996 CPAP 0 cm H 2 O 59.87 ± 30.12 61.53 ± 33.29 59.33 ± 29.59 58.27 ± 31.2 60.53 ± 32.45 0.999 B. G5 0.5 L/min 2 L/min 4 L/min 6 L/min 8 L/min p PSV 5/5 cm H 2 O 43.67 ± 21.03 43.4 ± 23.26 43 ± 19.96 45.67 ± 21.98 43.87 ± 20.75 0.998 CPAP 5 cm H 2 O 61.53 ± 29.52 63.53 ± 30.32 59 ± 27.28 57.73 ± 26.87 57.93 ± 27.57 0.976 CPAP 0 cm H 2 O 64 ± 26.63 63.67 ±31.71 62.53 ± 28.17 63.2 ± 27.74 63.27 ± 30.83 1.0 CPAP, continuous positive airway pressure; PSV, pressure support ventilation All values are expressed as mean ± standard deviation Table 3 Correlations among ventilator parameters: A. V300 Flow trigger Airway pressure RSBI MV V T RR PSV level PEEP Flow trigger 1 Airway pressure 0.008 1 RSBI 0.016 -0.357* 1 MV -0.019 0.339* 0.578** 1 V T 0.001 0.638** -0.730** 0.008 1 RR 0.014 -0.175 0.946** 0.797** -0.538** 1 PSV level 0.000 0.768** -0.272 0.549** 0.679** -0.029 1 PEEP 0.000 0.898** -0.141 0.281 0.344* -0.043 0.5** 1 B. G5 Flow trigger Airway pressure RSBI MV V T RR PSV level PEEP Flow trigger 1 Airway pressure -0.005 1 RSBI -1.08 -0.441** 1 MV -1.116 0.649** 0.301** 1 V T 0.94 0.654** -0.896** 0.054 1 RR -0.287 0.115 0.730** 0.682** -0.484** 1 PSV level 0.000 0.817** -0.367* 0.611** 0.621** 0.099 1 PEEP 0.000 0.817** -0.249 0.597** 0.414** 0.119 0.5** 1 MV, minute volume; PEEP, positive and end-expiratory pressure; PSV, pressure support ventilation; RR, respiratory rate; RSBI, rapid shallow breathing index; V T , tidal volume All values are expressed as r Spearman’s correlation coefficient * indicates p value < 0.05 ** indicates p value < 0.01 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7339226","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":504888358,"identity":"63abe46b-57ee-41e6-a786-a2978c659456","order_by":0,"name":"Hsin-Hsien Li","email":"","orcid":"","institution":"Chang Gung University","correspondingAuthor":false,"prefix":"","firstName":"Hsin-Hsien","middleName":"","lastName":"Li","suffix":""},{"id":504888359,"identity":"eec36e28-f110-4fc7-bb16-d5d9b842b134","order_by":1,"name":"Kai-Tien Chang","email":"","orcid":"","institution":"Chang Gung University","correspondingAuthor":false,"prefix":"","firstName":"Kai-Tien","middleName":"","lastName":"Chang","suffix":""},{"id":504888360,"identity":"f6964555-5933-4560-9996-d8c55e43ae0c","order_by":2,"name":"I-Hsin Lin","email":"","orcid":"","institution":"Chang Gung University","correspondingAuthor":false,"prefix":"","firstName":"I-Hsin","middleName":"","lastName":"Lin","suffix":""},{"id":504888361,"identity":"7233c871-b032-4a0e-afb3-68607b5e02ac","order_by":3,"name":"Yu-Rong Hsu","email":"","orcid":"","institution":"Chang Gung University","correspondingAuthor":false,"prefix":"","firstName":"Yu-Rong","middleName":"","lastName":"Hsu","suffix":""},{"id":504888362,"identity":"02af9f90-ffc8-4b67-9d30-352702a3ec07","order_by":4,"name":"Jennifer Shuangfan Wu","email":"","orcid":"","institution":"Chang Gung University","correspondingAuthor":false,"prefix":"","firstName":"Jennifer","middleName":"Shuangfan","lastName":"Wu","suffix":""},{"id":504888363,"identity":"f89d5f19-5823-4e2e-aba6-092b9df66ebb","order_by":5,"name":"Li-Chung Chiu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYJAC6R88NkCKhxQtDDJpCC1E6ZRmsDlMghZz9u7E2wU55+Xlw84eYPi4p5bBXiIBvxbLnrObrWecuW248XZeAuOMZ8cZeAhpMbiRu02Ct+d2guHsHANmngPHGHikidLy7xyJWqR5eA4kyEuDtdQQ1gLyi+UMnmTDDUAtB2ccOMDDc/8Bfi3m7L0bb3zgsZOXn51j+ODDgTo59p4DBBwGZwAVAtFhwjEJ1yLfAKbqCOoYBaNgFIyCkQcAhrhDIsxd+eMAAAAASUVORK5CYII=","orcid":"","institution":"Chang Gung Memorial Hospital","correspondingAuthor":true,"prefix":"","firstName":"Li-Chung","middleName":"","lastName":"Chiu","suffix":""}],"badges":[],"createdAt":"2025-08-10 13:53:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7339226/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7339226/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90035815,"identity":"6f01a03c-4ccc-4f42-90a2-2f0da94d2d14","added_by":"auto","created_at":"2025-08-27 15:49:46","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":215876,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration showing the experiment setup\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-7339226/v1/6bffebeadb4569aebd6d922f.png"},{"id":90035816,"identity":"77dde8a5-5680-4372-888f-ecc94ae27caa","added_by":"auto","created_at":"2025-08-27 15:49:46","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":190959,"visible":true,"origin":"","legend":"\u003cp\u003eBland-Altman plots showing the agreement between RSBI measured via handheld spirometer and values displayed by two ventilators in various operating modes. (A) V300 in CPAP mode at 5 cm H\u003csub\u003e2\u003c/sub\u003eO; (B) V300 in CPAP mode at 0 cm H\u003csub\u003e2\u003c/sub\u003eO; (C) G5 in CPAP mode at 5 cm H\u003csub\u003e2\u003c/sub\u003eO; (D) G5 in CPAP mode at 0 cm H\u003csub\u003e2\u003c/sub\u003eO\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCPAP, continuous positive airway pressure; RSBI, rapid shallow breathing index\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-7339226/v1/17393dafa7484fc5b9f60446.png"},{"id":90034963,"identity":"3f063cdf-ef6f-4430-b3d2-c725c4fb1fca","added_by":"auto","created_at":"2025-08-27 15:41:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":245638,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between RSBI measured by the handheld spirometer and the single or averaged values displayed by the ventilator. (A, B) V300 in CPAP mode at 5 cm H\u003csub\u003e2\u003c/sub\u003eO; (C, D) V300 in CPAP mode at 0 cm H\u003csub\u003e2\u003c/sub\u003eO; (E, F) G5 in CPAP mode at 5 cm H\u003csub\u003e2\u003c/sub\u003eO;\u003c/p\u003e\n\u003cp\u003e(G, H) G5 in CPAP mode at 0 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n\u003cp\u003eCPAP, continuous positive airway pressure; RSBI, rapid shallow breathing index\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-7339226/v1/c1bbecb1d52c66a511932ff1.png"},{"id":92295106,"identity":"a4d9c1c0-d8de-4ab2-a4dd-3acdc6823399","added_by":"auto","created_at":"2025-09-27 00:57:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1292646,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7339226/v1/491c0b6f-8e84-4e7f-9302-b19fb3562521.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparing Ventilator-displayed Rapid Shallow Breathing Index Values Versus Standard Measurement Techniques: A Bench Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWeaning critically ill patients from mechanical ventilation remains a significant challenge, requiring a delicate balance between the risk of premature extubation failure and avoiding unnecessary prolonged mechanical ventilation. The rapid shallow breathing index (RSBI) is used by clinicians to assess the probability of successful liberation from mechanical ventilation as a guide to decision-making during the weaning process [1]. The threshold defined by Yang and Tobin in 1991 (\u0026le;\u0026thinsp;105 breaths/min/L) achieved 97% sensitivity, 64% specificity, 78% positive predictive value, and 95% negative predictive value [2]. Although meta-analyses have confirmed that SBT is the most effective predictor of successful extubation [3], studies showed that up to 13% of patients who pass SBT may still require reintubation [4]. In real practice, RSBI is assessed after an SBT to help respiratory therapists make informed and cautious extubation decisions.\u003c/p\u003e\u003cp\u003eSpontaneous breathing is generally assessed according to respiratory frequency and tidal volume (V\u003csub\u003eT\u003c/sub\u003e) through an endotracheal tube, based on readings obtained using a handheld Wright spirometer during the first minute after disconnecting the patient from the ventilator [2]. While this method is considered the gold standard, it requires patient cooperation, specialized equipment, and disconnection from the ventilator, which increases the risk of aerosol dispersion and the potential spread of hospital-acquired acute respiratory infections [5]. To address these limitations, intensive care unit (ICU) ventilators have been developed to calculate RSBI values without disconnecting the patient and then display the results directly on the ventilator screen [6, 7].\u003c/p\u003e\u003cp\u003eMany current ICU ventilators can display the RSBI values on these systems, which are calculated on a breath-to-breath basis, depending on the algorithm. Numerous studies have assessed the accuracy of RSBI measurements, particularly those obtained in spontaneous breathing modes, such as pressure support ventilation (PSV), continuous positive airway pressure (CPAP), and T-piece configurations [6\u0026ndash;11]. RSBI measurements are relatively unaffected by the time at which they are taken or by changes in the fraction of inspired oxygen [10,11]. Desai et al. proposed using CPAP 5 cmH\u003csub\u003e2\u003c/sub\u003eO measurements obtained through the ventilator as an alternative to standard RSBI measurements. They observed that those values were lower than those obtained using a handheld spirometer and identified base flow variables that can significantly affect RSBI estimates [7]. Some experts have hypothesized that the higher pressure delivered by the base flow compensates for the resistance of the tubing, leading to significantly lower RSBI measurements [6]. Researchers have also reported discrepancies in RSBI values attributed to the patient\u0026rsquo;s underlying condition. Moreover, the administration of 5 cmH\u003csub\u003e2\u003c/sub\u003eO positive end-expiratory pressure (PEEP) has been shown to affect RSBI values, particularly after cardiac surgery [10].\u003c/p\u003e\u003cp\u003eGiven the limitations of spirometer availability, the risk of aerosol dispersion, and infection control concerns, it is crucial to identify ventilator parameters that yield RSBI values comparable to those obtained with a spirometer. This study aimed to evaluate the accuracy of ventilator-displayed RSBI values against the gold standard using a lung simulator. This study also sought to determine whether ventilatory settings affect RSBI values.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eStudy design\u003c/h2\u003e\n \u003cp\u003eThis laboratory study was conducted between September and November 2024 at the Respiratory Therapy Laboratory of Chang Gung University in Taoyuan, Taiwan. Throughout the experiments, room temperature was maintained at 25\u0026deg;C with an atmospheric pressure of 760 mmHg. The gas was held in the Ambient Temperature Pressure Saturated (ATPS) state. The laboratory is equipped with a stable medical gas system supplying oxygen at 50\u0026thinsp;\u0026plusmn;\u0026thinsp;5 pounds per square inch (PSI) and air at 50\u0026thinsp;\u0026plusmn;\u0026thinsp;5 PSI. A lung simulator was used to mimic spontaneous breathing in patients. Three lung conditions were simulated to replicate the pulmonary characteristics associated with obstructive lung disease, restrictive lung disease, and normal lungs.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eASL 5000 simulation\u003c/h3\u003e\n\u003cp\u003eTo replicate real-world clinical scenarios involving patient intubation, this study employed an ASL 5000 lung simulator (IngMar Medical, Pittsburgh, Pennsylvania, U.S.A.) connected to a manikin via a 7.5 mm endotracheal tube. This system features a computer-controlled piston that displaces gas at preset volumes to mimic spontaneous breathing. The movement of the piston is governed by equations of motion based on the respiratory system, allowing precise adjustments of airway resistance (Raw), respiratory system compliance (Crs), respiratory rate (RR), and inspiratory time (Ti), thereby simulating the effort of inspiratory muscles (Pmus) under various mechanical conditions.\u003c/p\u003e\n\u003cp\u003eBased on a review of the literature [12] and manufacturer guidelines [13], this study focused on three distinct respiratory patterns:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003cp\u003eNormal: Raw\u0026thinsp;=\u0026thinsp;13 cmH\u003csub\u003e2\u003c/sub\u003eO/L/s; Crs\u0026thinsp;=\u0026thinsp;50 mL/cmH\u003csub\u003e2\u003c/sub\u003eO; Pmus\u0026thinsp;=\u0026thinsp;13 cmH\u003csub\u003e2\u003c/sub\u003eO; RR\u0026thinsp;=\u0026thinsp;15\u0026thinsp;\u0026plusmn;\u0026thinsp;3 breaths/min; Ti\u0026thinsp;=\u0026thinsp;0.8 s.\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003eObstructive: Raw\u0026thinsp;=\u0026thinsp;21 cmH\u003csub\u003e2\u003c/sub\u003eO/L/s; Crs\u0026thinsp;=\u0026thinsp;60 mL/cmH\u003csub\u003e2\u003c/sub\u003eO; Pmus\u0026thinsp;=\u0026thinsp;14 cmH\u003csub\u003e2\u003c/sub\u003eO; RR\u0026thinsp;=\u0026thinsp;18\u0026thinsp;\u0026plusmn;\u0026thinsp;3 breaths/min; Ti\u0026thinsp;=\u0026thinsp;1s.\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003eRestrictive: Raw\u0026thinsp;=\u0026thinsp;10 cmH\u003csub\u003e2\u003c/sub\u003eO/L/s; Crs\u0026thinsp;=\u0026thinsp;25 mL/cmH\u003csub\u003e2\u003c/sub\u003eO; Pmus\u0026thinsp;=\u0026thinsp;15 cmH\u003csub\u003e2\u003c/sub\u003eO; RR\u0026thinsp;=\u0026thinsp;30\u0026thinsp;\u0026plusmn;\u0026thinsp;3 breaths/min; Ti\u0026thinsp;=\u0026thinsp;0.8 s.\u003c/p\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003ch3\u003eVentilator settings and monitoring\u003c/h3\u003e\n\u003cp\u003eThis study conducted tests using two ventilators: Hamilton Medical G5 (Switzerland) and Dr\u0026auml;ger V300 (Germany). Ventilator modes included CPAP (0 and 5 cmH\u003csub\u003e2\u003c/sub\u003eO), PSV (5 cmH\u003csub\u003e2\u003c/sub\u003eO), and PEEP (5 cmH\u003csub\u003e2\u003c/sub\u003eO). The impact of flow trigger settings on ventilator-measured values was assessed at 5 flow rates: 0.5, 2, 4, 6, and 8 L/min. Airway pressure was recorded using an electronic manometer (GB 60, GaleMed, Yilan, Taiwan) positioned at the Y-piece of the ventilator circuit.\u003c/p\u003e\n\u003ch3\u003eMeasuring of RSBI\u003c/h3\u003e\n\u003cp\u003eRSBI values were obtained from two ventilator readings or a handheld spirometer (Haloscale, Ferraris Medical Inc., Louisville, Colorado, U.S.A.). Measurements were obtained at 0, 15, 30, 45, and 60 seconds under three spontaneous modes: CPAP (5 cmH\u003csub\u003e2\u003c/sub\u003eO), CPAP (0 cmH\u003csub\u003e2\u003c/sub\u003eO), and PSV (5 cmH\u003csub\u003e2\u003c/sub\u003eO) with PEEP (5 cmH\u003csub\u003e2\u003c/sub\u003eO). A one-minute stabilization period was allowed after each adjustment of ventilator settings before measurements were recorded.\u003c/p\u003e\n\u003cp\u003eThe G5 ventilator displayed RSBI values (denoted as RSB) in real-time on its screen. This value was calculated as the total respiratory rate (fTotal) divided by exhaled tidal volume (VTE), provided that at least 80% of the breaths during the last 25 cycles\u003c/p\u003e\n\u003cp\u003ewere spontaneous in adult ventilation mode. The V300 ventilator also displayed RSBI values (denoted as RSB) in real-time on the ventilator screen. This value was calculated as the spontaneous respiratory rate (RRspon) divided by spontaneous tidal volume (VTspon).\u003c/p\u003e\n\u003cp\u003eWhen using the handheld device, measurements were obtained by disconnecting the ventilator to record MV. V\u003csub\u003eT\u003c/sub\u003e was then calculated by dividing MV by the RR, and RSBI was determined by dividing RR by V\u003csub\u003eT\u003c/sub\u003e.\u003c/p\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003eStatistical Analysis\u003c/h2\u003e\n \u003cp\u003eContinuous variables are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. The mean flow trigger settings as well as the mean RSBI, V\u003csub\u003eT\u003c/sub\u003e, RR, and MV values were compared across operating modes and between the two ventilators using ANOVA or the Kruskal-Wallis test, followed by post hoc analysis where applicable. Analysis was performed using Prism GraphPad 8.0 (GraphPad Software, Boston, Massachusetts, U.S.A.) with a \u003cem\u003ep\u003c/em\u003e-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 considered statistically significant. Pearson or Spearman\u0026rsquo;s correlation was used to assess the relationship between airway pressure, flow trigger settings, and other parameters using SPSS 26.0 (IBM, U.S.A.). Correlation coefficients with a 95% confidence interval were reported, and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eFig. 1 presents a schematic illustration of the experiment setup. A total of 480 measurements were collected, with each measurement obtained using all 4 methods (PSV 5/5 cm H\u003csub\u003e2\u003c/sub\u003eO, CPAP 5 cm H\u003csub\u003e2\u003c/sub\u003eO, CPCP 0 cm H\u003csub\u003e2\u003c/sub\u003eO, handheld spirometer) across the three lung simulations. Data from the three breathing patterns were pooled for analysis.\u003c/p\u003e\n\u003cp\u003eNotable differences were observed between the mean RSBI, V\u003csub\u003eT\u003c/sub\u003e, RR, and MV values obtained using the two ventilators and those measured using the handheld spirometer (Table 1). In PSV mode, the mean RSBI of the V300 ventilator (41.61 \u0026plusmn; 18.64 vs. 59.73 \u0026plusmn; 24, \u003cem\u003ep\u003c/em\u003e = 0.003) was significantly lower than the handheld values, while the mean V\u003csub\u003eT\u003c/sub\u003e (500.47 \u0026plusmn; 79.91 vs. 366.58 \u0026plusmn; 37.16, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) and mean MV (9.87 \u0026plusmn; 2.01 vs. 7.57 \u0026plusmn; 1.84, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) were significantly higher. Similarly, the mean RSBI of the G5 ventilator in PSV mode (43.92 \u0026plusmn; 20.86 vs. 59.73 \u0026plusmn; 24, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.045) was significantly lower than the handheld values, while the mean V\u003csub\u003eT\u003c/sub\u003e (508.33 \u0026plusmn; 82.22 vs. 366.58 \u0026plusmn; 37.16, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001), and mean MV (10.06 \u0026plusmn; 1.53 vs. 7.57 \u0026plusmn; 1.84, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) were significantly higher. In CPAP 5 and 0 cm H\u003csub\u003e2\u003c/sub\u003eO modes, no significant differences were observed between the RSBI, V\u003csub\u003eT\u003c/sub\u003e, RR, and MV values from ventilators versus handheld devices. Note that RR did not exhibit significant differences under any of the tested conditions.\u003c/p\u003e\n\u003cp\u003eSubsequent analysis of RSBI values as a function of trigger flow settings across ventilatory modes revealed further insights. The flow trigger was set at 0.5, 2, 4, 6, and 8 L/min. Mean RSBI values were consistent across both ventilators and showed no significant differences across trigger flow settings, irrespective of ventilatory mode (Table 2). To further investigate the impact of the flow trigger, we examined its correlation with other parameters. No significant correlations were identified between flow trigger settings and RSBI, MV, V\u003csub\u003eT\u003c/sub\u003e, RR, PSV level, or PEEP (Tables 3A and 3B).\u003c/p\u003e\n\u003cp\u003eTables 3A and 3B list the correlations between airway pressure and other parameters. Regardless of which ventilator was used (V300 or G5), significant correlations were observed between airway pressure and the following parameters: RSBI (r = -0.357, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05 ; r = -0.441, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01), MV (r = 0.339, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05 ; r = 0.649, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01), V\u003csub\u003eT\u003c/sub\u003e (r = 0.638, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01; r = 0.654, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01), PSV level (r = 0.768, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001 ; r = 0.817, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01), and PEEP (r = 0.898, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01 ; r = 0.817, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01). No significant correlation was observed between airway pressure and RR. Regardless of which ventilator was used, RSBI was significantly correlated with the following parameters: MV (r = 0.578, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01; r = 0.301, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01), V\u003csub\u003eT\u003c/sub\u003e (r = -0.730, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01 ; r = -0.896, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01), and RR (r = 0.946, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01; r = 0.730, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01). RSBI was significantly correlated with PSV when using the V300 ventilator (r = -0.367, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05). Interactions were also observed among parameters, including MV, V\u003csub\u003eT\u003c/sub\u003e, RR, PSV level, and PEEP.\u003c/p\u003e\n\u003cp\u003eConsistency between ventilator measurements and the standard handheld method was assessed in terms of mean RSBI values recorded from 0 to 60 seconds. The V300 ventilator demonstrated good agreement with the handheld spirometer when used in CPAP 5 or 0 cmH\u003csub\u003e2\u003c/sub\u003eO mode. In CPAP mode at 5 cmH\u003csub\u003e2\u003c/sub\u003eO, the bias was 3.654 and precision was 4.507 (range: -5.179 to 12.49) (Fig. 2A). In CPAP mode at 0 cmH\u003csub\u003e2\u003c/sub\u003eO, the bias was 3.921 and precision was 2.46 (range: -0.899 to 8.742) (Fig. 2B). The mean difference in RSBI values between the G5 ventilator and spirometer was as follows: CPAP 5 cmH\u003csub\u003e2\u003c/sub\u003eO (-1.132; range: -12.65 to 10.3) (Fig. 2C) and CPAP 0 cmH\u003csub\u003e2\u003c/sub\u003eO (-4.519; range: -17.19 to 8.152) (Fig. 2D).\u003c/p\u003e\n\u003cp\u003eCorrelation analysis using Spearman\u0026rsquo;s correlation coefficient revealed a strong, statistically significant relationship between the RSBI value obtained from the spirometer and the average RSBI value from 0 to 60 seconds in the CPAP mode of both ventilators. The Spearman\u0026rsquo;s correlation coefficients were 0.846, 0.966, 0.900, and 0.869, respectively (Fig. 3A, 3C, 3E, 3G). Similarly, a high correlation was observed between the RSBI value from the handheld spirometer and the RSBI value at 60 seconds (r = 0.832, 0.904, 0.845, 0.876; all \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) (Fig. 3B, 3D, 3F, 3H).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo the best of our knowledge, this is the first study to use lung simulation to compare the accuracy of RSBI values measured by a ventilator versus those obtained using a handheld spirometer. In PSV mode, the average RSBI values were significantly lower than those measured using the spirometer; however, no differences were detected in CPAP mode. No significant differences in mean RSBI values were detected across flow trigger settings, irrespective of the operating mode. The choice of flow trigger was not correlated with airway pressure, RSBI, MV, V\u003csub\u003eT\u003c/sub\u003e, RR, PSV level, or PEEP.\u003c/p\u003e\n\u003cp\u003eWhen patients enter the weaning process, SBTs can be conducted using either the PSV method or T-piece method [14]. Numerous studies have assessed the accuracy and validity of alternative RSBI measurement methods during SBT. It has been reported that the RSBI values during PSV at 5 cmH\u003csub\u003e2\u003c/sub\u003eO are lower than those using the T-piece method [11]. Similarly, our RSBI values recorded in PSV mode were significantly lower than those derived using a handheld spirometer. This can be partially attributed to higher V\u003csub\u003eT\u003c/sub\u003e and MV without RR variation. We theorize that higher pressure support facilitates the delivery of greater tidal volumes, thereby reducing the RSBI ratio. PSV is more effective than the T-piece method in overcoming the resistance created by the endotracheal tube and ventilator circuit [15] to reduce respiratory effort [16]. However, the compensation for resistance from the endotracheal tube is absent when measurements are obtained using a spirometer. Consequently, PSV reduces the calculated RSBI value, which may lead to an overestimation of the patient\u0026apos;s readiness to be weaned off ventilatory support.\u003c/p\u003e\n\u003cp\u003eAt present, the effect of PEEP on RSBI remains a topic of debate. One study reported that CPAP at 5 cm H\u003csub\u003e2\u003c/sub\u003eO influenced RSBI assessments in post-cardiac surgery patients [10]. Another study on 60 mechanically ventilated patients reported no difference between values obtained using a Wright spirometer and those obtained using a ventilator with the CPAP set to zero [8]. In the current study, RSBI values measured in CPAP at 0 or 5 cmH\u003csub\u003e2\u003c/sub\u003eO were essentially identical to those obtained using a spirometer, probably due to the relatively low pressure in CPAP mode.\u003c/p\u003e\n\u003cp\u003ePrevious studies have reported that RSBI measurements obtained through the ventilator were affected by flow-by mode. However, this issue remains unclear. Patel et al. reported no difference between RSBI values based on a handheld spirometer and those obtained through the ventilator under CPAP 0 or PS 0 cmH\u003csub\u003e2\u003c/sub\u003eO without flow-by [8]. Kheir et al. reported that RSBI values measured through the ventilator without a flow trigger were higher than those obtained using a digital spirometer [6]. Those researchers posited that the pressure provided by the base flow not only compensated for the resistance of the tubing but also reduced of the workload imposed by breathing, thereby lowering the RSBI value.\u003c/p\u003e\n\u003cp\u003eThis study obtained contradictory findings. First, modern ventilators provide continuous base flow (e.g., 2 L/min), regardless of whether the user sets the flow trigger or pressure trigger to zero. This suggests that flow is always present in spontaneous modes, regardless of the settings. Second, every ventilator has its own flow trigger range. When assessing the impact of flow trigger settings, we found that the actual flow adhered to the rule of maintaining a base flow 2 L/min above the zero-flow trigger baseline. The base flow rates of the V300 ventilator were set at 2, 4, 6, 8, and 10 L/min. The G5 ventilator followed a doubling rule, generating base flow rates of 2, 4, 8, 12, and 16 L/min. Our analysis revealed no significant variations in RSBI values under base flow rates of 0.5, 2, 4, 6, or 8 L/min. Moreover, no correlations were detected between flow trigger settings and other parameters. Third, no correlation was detected between airway pressure and the flow trigger. In flow trigger mode, the delivery of base flow generates pressure; however, the flow trigger itself has no direct influence on pressure in the airway. Moreover, our analysis revealed that airway pressure is strongly correlated with PSV levels and PEEP, which suggests the contribution of these factors in compensating for the resistance of the tubing, thereby reducing RSBI values.\u003c/p\u003e\n\u003cp\u003eUsing the average of five ventilator-displayed RSBI values over a period of 0\u0026ndash;60 s yielded a stronger correlation than did interval measurements at 0\u0026ndash;15, 0\u0026ndash;30, and 0\u0026ndash;45 s [9]. In the current study, ventilator-displayed RSBI was averaged across five time points (0, 15, 30, 45, and 60s) under three different lung conditions to enhance clinical applicability. This study also addressed possible interactions among ventilator parameters to strengthen the power of this analysis. Our findings confirmed that RSBI values in CPAP mode were highly consistent with those measured using the spirometer method, aligning with previous clinical studies [9]. It is important to consider that ventilator-displayed RSBI values are based on an accumulation of breaths over the preceding seconds rather than a single breath. Our results also revealed a strong correlation between RSBI values displayed at 60 seconds and those based on manual measurements using a handheld spirometer, which suggests that consistent and reliable results can be obtained from single-point measurements. The ability to assess the patient\u0026rsquo;s condition based on a single ventilator-displayed RSBI value would be convenient for respiratory therapists in real-world clinical applications.\u003c/p\u003e\n\u003cp\u003eThis study was subject to several limitations that should be considered when interpreting our findings. First, this bench study was based on a lung model rather than actual patients. Our findings provide valuable operational insights for clinicians; however, this research lacked data related to patient prognosis or extubation outcomes, which limits the ability to extrapolate the findings to predict weaning success rates. Second, the study examined only two ventilators, both of which were servo-valve devices with similar base flow levels. It is possible that different ventilator designs would provide different results. Third, only flow trigger mode was used to activate the ventilators; pressure trigger mode was not tested or included in the analysis. It is important to note that modern ventilators maintain a constant base flow to sense the patient\u0026rsquo;s breathing effort, regardless of whether flow or pressure triggers are used. Future studies should focus on replicating and validating these findings in clinical settings with actual patients to assess their applicability and impact on clinical outcomes.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study compared the accuracy of RSBI values obtained from ventilators with the gold standard method using a lung simulator designed to mimic spontaneous breathing under normal, obstructive, and restrictive conditions. Two ventilators were tested under three modes: CPAP at 0 cmH\u003csub\u003e2\u003c/sub\u003eO; CPAP at 5 cmH\u003csub\u003e2\u003c/sub\u003eO, and PSV at 5 cmH\u003csub\u003e2\u003c/sub\u003eO with PEEP of 5 cmH\u003csub\u003e2\u003c/sub\u003eO. RSBI values displayed by the ventilators were recorded at 0, 15, 30, 45, and 60 seconds. RSBI values displayed by the ventilator in PSV mode were significantly lower than those obtained using a handheld device. No discrepancies were observed in CPAP mode, and flow trigger settings did not have a significant effect on RSBI measurements. Clinicians should be cautious of the deviation in RSBI values captured in PSV mode. Our findings suggest that CPAP mode may be a more suitable option for assessing weaning readiness. Future research will be required to verify these findings in clinical practice.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCPAP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eContinuous positive airway pressure\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCrs\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCompliance\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eICU\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIntensive care units\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePEEP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePositive and end-expiratory pressure\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePSI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePounds per square inch\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePSV\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePressure support ventilation\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eRaw\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eresistance\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eRSBI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eRapid shallow breathing index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSBT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eSpontaneous breathing trials\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eAll authors declared no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank the Department of Respiratory Therapy at Chang Gung University for assistance during the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSupplementary Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eH.-H. Li, K.-T. Chang, I.-H. Lin, Y.-R. Hsu, and J.-S. Wu conceived and designed research; H.-H. Li and L.-C. Chiu drafted the manuscript; H.-H. Li and L.-C. Chiu edited and revised the manuscript. H.-H. Li, K.-T. Chang, I.-H. Lin, Y.-R. Hsu, and J.-S. Wu prepared the figures. All authors interpreted the results and approved the final version of the manuscript prior to submission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by funding from the student research project at Chang Gung University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData supporting the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors declare that no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKarthika M, Al Enezi FA, Pillai LV, Arabi YM. Rapid shallow breathing index. Ann Thorac Med. 2016;11(3):167-76.\u003c/li\u003e\n\u003cli\u003eYang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med. 1991;324(21):1445-50.\u003c/li\u003e\n\u003cli\u003eTrivedi V, Chaudhuri D, Jinah R, Piticaru J, Agarwal A, Liu K, et al. The Usefulness of the Rapid Shallow Breathing Index in Predicting Successful Extubation: A Systematic Review and Meta-analysis. Chest. 2022;161(1):97-111.\u003c/li\u003e\n\u003cli\u003eBoles JM, Bion J, Connors A, Herridge M, Marsh B, Melot C, et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-56.\u003c/li\u003e\n\u003cli\u003eTang S, Mao Y, Jones RM, Tan Q, Ji JS, Li N, et al. Aerosol transmission of SARS-CoV-2? Evidence, prevention and control. Environ Int. 2020;144:106039.\u003c/li\u003e\n\u003cli\u003eKheir F, Myers L, Desai NR, Simeone F. The effect of flow trigger on rapid shallow breathing index measured through the ventilator. J Intensive Care Med. 2015;30(2):103-6.\u003c/li\u003e\n\u003cli\u003eDesai NR, Myers L, Simeone F. Comparison of 3 different methods used to measure the rapid shallow breathing index. J Crit Care. 2012;27(4):418.e1-6.\u003c/li\u003e\n\u003cli\u003ePatel KN, Ganatra KD, Bates JH, Young MP. Variation in the rapid shallow breathing index associated with common measurement techniques and conditions. Respir Care. 2009;54(11):1462-6.\u003c/li\u003e\n\u003cli\u003eRittayamai N, Ratchaneewong N, Tanomsina P, Kongla W. Validation of rapid shallow breathing index displayed by the ventilator compared to the standard technique in patients with readiness for weaning. BMC Pulm Med. 2021;21(1):310.\u003c/li\u003e\n\u003cli\u003eEl-Khatib MF, Jamaleddine GW, Khoury AR, Obeid MY. Effect of continuous positive airway pressure on the rapid shallow breathing index in patients following cardiac surgery. Chest. 2002;121(2):475-9.\u003c/li\u003e\n\u003cli\u003eEl-Khatib MF, Zeineldine SM, Jamaleddine GW. Effect of pressure support ventilation and positive end expiratory pressure on the rapid shallow breathing index in intensive care unit patients. Intensive Care Med. 2008;34(3):505-10.\u003c/li\u003e\n\u003cli\u003eChen Y, Yuan Y, Zhang H, Li F. Accuracy of the estimations of respiratory mechanics using an expiratory time constant in passive and active breathing conditions: a bench study. Eur J Med Res. 2023;28(1):195.\u003c/li\u003e\n\u003cli\u003eMedical I. RespiSim\u0026reg; Scenarios: IngMar Medical; [Available from: https://www.ingmarmed.com/product/respisim-scenarios/.\u003c/li\u003e\n\u003cli\u003eThille AW, Gacouin A, Coudroy R, Ehrmann S, Quenot JP, Nay MA, et al. Spontaneous-Breathing Trials with Pressure-Support Ventilation or a T-Piece. N Engl J Med. 2022;387(20):1843-54.\u003c/li\u003e\n\u003cli\u003eBrochard L, Rua F, Lorino H, Lemaire F, Harf A. Inspiratory pressure support compensates for the additional work of breathing caused by the endotracheal tube. Anesthesiology. 1991;75(5):739-45.\u003c/li\u003e\n\u003cli\u003eSklar MC, Burns K, Rittayamai N, Lanys A, Rauseo M, Chen L, et al. Effort to Breathe with Various Spontaneous Breathing Trial Techniques. A Physiologic Meta-analysis. Am J Respir Crit Care Med. 2017;195(11):1477-85.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e RSBI, V\u003csub\u003eT\u003c/sub\u003e, RR, MV values averaged across 5 time points (0, 15, 30, 45, and 60 seconds)\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"1082\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.0108%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 5.6706%;\"\u003e\n \u003cp\u003eHandheld\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" style=\"width: 23.5824%;\"\u003e\n \u003cp\u003eV300\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"6\" style=\"width: 23.5824%;\"\u003e\n \u003cp\u003eG5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.0108%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003ePSV 5/5 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003eCPAP 5 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003eCPAP 0 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003csub\u003e1\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003csub\u003e2\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003csub\u003e3\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003ePSV 5/5 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003eCPAP 5 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003eCPAP 0 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003csub\u003e1\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003csub\u003e2\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003csub\u003e3\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.0108%;\"\u003e\n \u003cp\u003eRSBI\u003c/p\u003e\n \u003cp\u003e(cycle/min/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 5.6706%;\"\u003e\n \u003cp\u003e59.73 \u0026plusmn; 24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e41.61 \u0026plusmn; 18.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e55.16 \u0026plusmn; 22.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e54.89 \u0026plusmn; 23.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.821\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.794\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e43.92 \u0026plusmn; 20.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e59.95 \u0026plusmn; 27.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e63.33 \u0026plusmn; 28.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.045\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.935\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.0108%;\"\u003e\n \u003cp\u003eV\u003csub\u003eT\u003c/sub\u003e (ml)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 5.6706%;\"\u003e\n \u003cp\u003e366.58 \u0026plusmn; 37.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e500.47 \u0026plusmn; 79.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e373.32 \u0026plusmn; 57.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e374.92 \u0026plusmn; 53.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.969\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.943\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e508.33 \u0026plusmn; 82.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e369.09 \u0026plusmn; 56.01\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e352.05 \u0026plusmn; 53.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.765\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.0108%;\"\u003e\n \u003cp\u003eRR\u003c/p\u003e\n \u003cp\u003e(cycle/min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 5.6706%;\"\u003e\n \u003cp\u003e21.17 \u0026plusmn; 6.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e20.65 \u0026plusmn; 6.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e20.77 \u0026plusmn; 6.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e20.79 \u0026plusmn; 6.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.988\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e20.75 \u0026plusmn; 6.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e20.67 \u0026plusmn; 6.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e20.95 \u0026plusmn; 6.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.989\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.0108%;\"\u003e\n \u003cp\u003eMV (L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 5.6706%;\"\u003e\n \u003cp\u003e7.57 \u0026plusmn; 1.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e9.87\u0026nbsp;\u0026plusmn; 2.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e7.46 \u0026plusmn; 1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e7.37 \u0026plusmn; 1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e10.06 \u0026plusmn; 1.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e7.36 \u0026plusmn; 1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.5005%;\"\u003e\n \u003cp\u003e6.97 \u0026plusmn; 1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.3303%;\"\u003e\n \u003cp\u003e0.275\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCPAP, continuous positive airway pressure; MV, minute volume; PEEP, positive and end-expiratory pressure; PSV, pressure support ventilation; RR, respiratory rate; RSBI, rapid shallow breathing index; V\u003csub\u003eT\u003c/sub\u003e, tidal volume\u003c/p\u003e\n\u003cp\u003eAll values are expressed as mean\u0026nbsp;\u0026plusmn;\u0026nbsp;standard deviation\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eP\u003csub\u003e1\u003c/sub\u003e\u003c/em\u003e Comparing handheld vs. ventilator in PSV mode 5 cmH\u003csub\u003e2\u003c/sub\u003eO with PEEP 5 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eP\u003csub\u003e2\u003c/sub\u003e\u003c/em\u003e Comparing handheld vs. ventilator in CPAP mode 5 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eP\u003csub\u003e3\u003c/sub\u003e\u003c/em\u003e Comparing handheld vs. ventilator in CPAP mode 0 cmH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e RSBI values based on flow trigger settings for the two ventilators.\u003c/p\u003e\n\u003cp\u003eA. V300\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"763\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e0.5 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e2 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e4 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e6 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e8 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003ePSV 5/5 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e43.20 \u0026plusmn; 22.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e45.53 \u0026plusmn; 22.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e41.93 \u0026plusmn; 20.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e43.53 \u0026plusmn; 23.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e43.93 \u0026plusmn; 21.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e0.995\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003eCPAP 5 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e59.40 \u0026plusmn; 30.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e61.87 \u0026plusmn; 31.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e58.4 \u0026plusmn; 28.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e57.93 \u0026plusmn; 27.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e58 \u0026plusmn; 27.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e0.996\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 132px;\"\u003e\n \u003cp\u003eCPAP 0 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e59.87 \u0026plusmn; 30.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e61.53 \u0026plusmn; 33.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e59.33 \u0026plusmn; 29.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e58.27 \u0026plusmn; 31.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e60.53 \u0026plusmn; 32.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eB. G5\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"762\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 133px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e0.5 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e2 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e4 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e6 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e8 L/min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003ePSV 5/5 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e43.67 \u0026plusmn; 21.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e43.4 \u0026plusmn; 23.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e43 \u0026plusmn; 19.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e45.67 \u0026plusmn; 21.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e43.87 \u0026plusmn; 20.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003eCPAP 5 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e61.53 \u0026plusmn; 29.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e63.53 \u0026plusmn; 30.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e59 \u0026plusmn; 27.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e57.73 \u0026plusmn; 26.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e57.93 \u0026plusmn; 27.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.976\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003eCPAP 0 cm H\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e64 \u0026plusmn; 26.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e63.67 \u0026plusmn;31.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e62.53 \u0026plusmn; 28.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e63.2 \u0026plusmn; 27.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003e63.27 \u0026plusmn; 30.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCPAP, continuous positive airway pressure; PSV, pressure support ventilation\u003c/p\u003e\n\u003cp\u003eAll values are expressed as mean \u0026plusmn; standard deviation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e Correlations among ventilator parameters:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA. V300\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"1030\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003eFlow trigger\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eAirway pressure\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003eRSBI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eMV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eV\u003csub\u003eT\u003c/sub\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eRR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003ePSV level\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003ePEEP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eFlow trigger\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eAirway pressure\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.008\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eRSBI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e-0.357*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eMV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e-0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.339*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e0.578**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eV\u003csub\u003eT\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.638**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e-0.730**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.008\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eRR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e-0.175\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e0.946**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.797**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e-0.538**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003ePSV level\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.768**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e-0.272\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.549**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.679**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e-0.029\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003ePEEP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.898**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e-0.141\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.281\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.344*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e-0.043\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.5**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eB. G5\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"1030\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003eFlow trigger\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eAirway pressure\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003eRSBI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eMV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eV\u003csub\u003eT\u003c/sub\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eRR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003ePSV level\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003ePEEP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eFlow trigger\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eAirway pressure\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e-0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eRSBI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e-1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e-0.441**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eMV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e-1.116\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.649**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e0.301**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eV\u003csub\u003eT\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.654**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e-0.896**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.054\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003eRR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e-0.287\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e0.730**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.682**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e-0.484**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003ePSV level\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.817**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e-0.367*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.611**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.621**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.099\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003ePEEP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 123px;\"\u003e\n \u003cp\u003e0.817**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e-0.249\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.597**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.414**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.119\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e0.5**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eMV, minute volume; PEEP, positive and end-expiratory pressure; PSV, pressure support ventilation; RR, respiratory rate; RSBI, rapid shallow breathing index; V\u003csub\u003eT\u003c/sub\u003e, tidal volume\u003c/p\u003e\n\u003cp\u003eAll values are expressed as r Spearman\u0026rsquo;s correlation coefficient\u003c/p\u003e\n\u003cp\u003e* indicates \u003cem\u003ep\u003c/em\u003e value \u0026lt; 0.05\u003c/p\u003e\n\u003cp\u003e** indicates \u003cem\u003ep\u003c/em\u003e value \u0026lt; 0.01\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Rapid shallow breathing index, Flow trigger, Ventilator, Spirometer, Correlation, Consistency","lastPublishedDoi":"10.21203/rs.3.rs-7339226/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7339226/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eThe rapid shallow breathing index (RSBI) is a key indicator for assessing weaning readiness, based on simple and non-invasive measurements. However, the standard method requires patient cooperation, specialized equipment, and patient disconnection from the ventilator, which increases the risk of aerosol dispersion. Many modern ventilators address these limitations by displaying RSBI values directly on the screen; however, the accuracy and reliability of the displayed data have yet to be confirmed. This study compared the accuracy of RSBI values obtained from ventilators with the gold standard method using a lung simulator.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eThis bench study was conducted using a manikin equipped with a lung simulator designed to mimic spontaneous breathing under preset resistance and compliance (normal, obstructive, restrictive) conditions. Two ventilators were tested under three modes: continuous positive airway pressure (CPAP) at 0 and 5 cmH\u003csub\u003e2\u003c/sub\u003eO, and pressure support ventilation (PSV) at 5 cmH\u003csub\u003e2\u003c/sub\u003eO combined with positive end-expiratory pressure (PEEP) of 5 cmH\u003csub\u003e2\u003c/sub\u003eO. RSBI values displayed by the ventilators were recorded at 0, 15, 30, 45, and 60 seconds. The standard handheld method required disconnection of the ventilator to measure the minute volume (MV), from which tidal Volume (V\u003csub\u003eT\u003c/sub\u003e) and RSBI were calculated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eIn PSV mode, the average RSBI value was significantly lower than that measured using the spirometer; however, no difference was detected in CPAP mode. No significant differences in mean RSBI values were detected across different flow trigger settings, irrespective of the operating mode. The choice of flow trigger was not correlated with airway pressure, RSBI, MV, V\u003csub\u003eT\u003c/sub\u003e, respiratory rate, PSV level, or PEEP. Bland-Altman plots revealed good agreement between ventilator-measured RSBI values and those obtained using a handheld spirometer RSBI in CPAP mode.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eRSBI values presented by the ventilator in PSV mode were significantly lower than those obtained using a handheld device. No discrepancies were observed in CPAP mode, and flow trigger settings did not have a significant effect on RSBI measurements. Clinicians should be cautious of the deviation in RSBI values captured in PSV mode. Our findings suggest that CPAP mode may be a more suitable option for assessing weaning readiness.\u003c/p\u003e","manuscriptTitle":"Comparing Ventilator-displayed Rapid Shallow Breathing Index Values Versus Standard Measurement Techniques: A Bench Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-27 15:41:42","doi":"10.21203/rs.3.rs-7339226/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8c60032a-15b9-40d8-b1d7-587a4ac7c7b1","owner":[],"postedDate":"August 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-27T00:55:28+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-27 15:41:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7339226","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7339226","identity":"rs-7339226","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}