The low-flow mask oxygen is a more effective, comfortable, and easy-to-follow treatment for psychogenic hyperventilation syndrome: a double-blind, randomized controlled trial

The low-flow mask oxygen is a more effective, comfortable, and easy-to-follow treatment for psychogenic hyperventilation syndrome: a double-blind, randomized controlled trial | 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 Article The low-flow mask oxygen is a more effective, comfortable, and easy-to-follow treatment for psychogenic hyperventilation syndrome: a double-blind, randomized controlled trial Linhe Yang, Dongmei Yuan, Zhenyu Luo, Yunying Li, Xiuli Zhu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5720282/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 Objectives To compare the effect of low-flow mask oxygenation (LFMO) with breathing training (BT) for psychogenic hyperventilation syndrome (PHVS), providing more options and evidence for clinical treatment. Methods A randomized double-blinded controlled experiment was registered in the Chinese Clinical Trial Registry on 01/06/2023 with a defined number (ChiCTR2300072044) and approved by the Ethics Committee of (REDACT) (GYZXLL2023070) and then conducted there from 10 May 2024 to 23 November 2024. Participants with PHVS were blindly randomized into the LFMO group and the BT group, then the LFMO group inhaled 3L/minute oxygen with the oxygen mask and breathed freely, while the BT group performed the breath training led by researchers face-on-face. The recovery length from PHVS, the Nijmegen Questionnaire score at fifteen minutes since the intervention, the Nijmegen Questionnaire score at the end of the intervention, and the comfort/tolerance score (participant rating via NRS) were collected as the primary outcome. The secondary outcome was measured by the mean breath rate during the recovery (Calculated by dividing the total number of breaths during the intervention by time) and laboratory results, including the PH, lactate, K+, Ca2+, PO 2 , and PCo 2. Results Forty-five participants (all Asian) completed the study and were included in the analysis (21 for the LFMO group and 24 for the BT group), mainly female (75%, n=33). All demographic characteristics between the two groups are within the reasonable range and have no significant difference. However, significant differences were measured among the outcomes, including the oxygen index (480.22±29.64, 311.01±15.45, p<0.001), Mean breath rate during recovery (19.17±1.74,28.24±2.53, p<0.001), and the LFMO group showed significant advantages in both the length of recovery (22.94±2.81, p<0.001) and comfort/tolerance (5.86±1.24, p<0.001). Conclusion Compared to breath training therapy, the low-flow mask oxygenation is a more effective, comfortable, and easy-to-follow treatment for PHVS. Health sciences/Diseases/Psychiatric disorders Health sciences/Diseases/Respiratory tract diseases Biological sciences/Physiology/Respiration hyperventilation low-flow oxygen breath training psychogenic hyperventilation Figures Figure 1 Introduction Background Psychogenic hyperventilation is common in emergency departments (ED) worldwide, which has been defined as “respiratory rate (>20 minutes) increased at or before the ED visit, and can not be explained by somatic causes [1]”, people inhale oxygen and exhale carbon dioxide too much in a short period, and some of them could be aggravated into Psychogenic hyperventilation syndrome (PHVS) [2, 3, 15] and finally result in emergency visits [1, 5, 13, 14]. For its easy-to-use and non-invasive features [8, 10, 12], breath training (BT) has long attracted physicians’ attention and has become the most-using treatment for psychogenic hyperventilation syndrome (PHVS). However, the PHVS could result in a series of uncomfortable physical feelings, including breath shortness, tingling fingers, chest pain, etc., then provoke psychological symptoms such as anxiety, fear, and even panic disorder [5, 9, 12, 13, 14, 16], causing the patient to believe that they are lacking in oxygen falsely, thus speeding up breathing and falling into a vicious circle; by this way, it could never be easy for medical staffs to calm and teach patients to adjust their breath mode in ED practice. Although a Cochrane evidence-based review has questioned the effectiveness of breath training and called for a new, safe treatment [10], existing studies have still focused on studying the effects of BT with some methodological limitations acknowledged by the authors themselves, such as relying on participants’ self-report symptoms, lack of convincing standards to diagnose the PHVS [5, 8, 10, 17], besides, as more PHVS related factors emerged through new studies, such as ambient temperature [13], further undermining the credibility of previous studies, a study for new safe treatment is urgent. Inspired by the Chinese expert consensus on ED oxygen treatment [7], which mentioned that oxygen masks with low oxygen flow (<5L/minute) could lead to carbon dioxide rebreathing. We hypothesize that using oxygen masks with oxygen flow <5L/minute could be a better treatment for PHVS in the ED setting, as the physiological changes opposite to PHVS and the use of medical equipment and oxygen supply could psychologically calm the patients. Objectives of this study This study compares the effect of low-flow mask oxygenation (LFMO) with breathing training (BT) for psychogenic hyperventilation syndrome (PHVS), providing more options and evidence for clinical treatment. MATERIALS AND METHODS Study design and setting A randomized double-blinded controlled experiment was registered in the Chinese Clinical Trial Registry on 01/06/2023 with a defined number (ChiCTR2300072044) and approved by the Ethics Committee of (REDACT) (GYZXLL2023070) and then conducted in there from 10 May 2024 to 23 November 2024, which is the region's largest referral, medical, and teaching center was certificated with the national trauma center, chest pain center, and Stroke center in 2016, 2018, and 2019 separately, it consists of two hospital areas, treating over 20000 emergency visits annually. Participants recruiting The sample size calculation for this study was based on the pilot study with 24 volunteers [11], in which the mean duration from diagnosing PHVS to recovery was 27.6±2.3 minutes in the breath training group (BT group) and 21.4±2.5 minutes in the low-flow mask oxygenation group (LFMO group). Assuming α = 0.05 (two-tailed) and 1-β=90% for this study, 18 study subjects were required in each group, and considering a 10% shedding rate, 20 study subjects had to be recruited in each group, making a total of 40 cases in both groups. Patients who met the following criteria were recruited, and informed consent was obtained from the participants or next to kin: (1) Inclusion criteria: (i) age ≥18 years; (ii) diagnosed as PHVS and reconfirmed by arterial blood gas analysis and the Nijmegen Questionnaire; (iii)voluntary participation in this study; (2) Exclusion criteria: (i) having a history of significant organic pathology or respiratory disease; (ii) coagulation disorders; (iii) have the presence of PHVS before; (iiii) presence of factors that may cause carbon dioxide retention (e.g., BMI≥25, chest trauma) [7]; (v) communication disorders; (vi) abnormal body temperature (＜36℃ or ≥37.3 ℃). Randomization and blinding A simple randomized grouping method was conducted, where the participants blindly drew a unique number, and then the project leader used a computer program to divide all numbers equally to LFMO and BT groups randomly. The project leader is responsible for the participants’ recruitment, random grouping, and keeping information. The other researchers who performed the intervention were not informed of their assignment to groups, nor were they informed of the difference between the two interventions; they were not allowed to communicate with the rest of the participants throughout the experiment to avoid disclosure of the grouping. The participants were informed of the purpose of the study, the procedures, and the possible symptoms of the study before the start of the experiment but were not informed of their assignment to the experimental group or the control group, nor were they informed of the differences between the two groups; they were asked to remain strictly confidential throughout the experiment and were not allowed to communicate with the rest of the participants to minimize implementation bias. The two groups conducted interventions separately, and each participant was accompanied by two researchers who were responsible for the intervention (figure 1). Variables and measurement Gender, age, weight, BMI, ASI, the Nijmegen Questionnaire scores at admission, body temperature, time from PHVS onset to admission, and mean pre-intervention respiratory rate (Calculated by dividing the total number of breaths from grouping to intervention by time) were collected as the characteristic data. The recovery length from PHVS, the Nijmegen Questionnaire score at fifteen minutes since the intervention, the Nijmegen Questionnaire score at the end of the intervention, and the comfort/tolerance score (participant rating via NRS) were collected as the primary outcome. The secondary outcome was measured by the mean breath rate during the recovery (Calculated by dividing the total number of breaths during the intervention by time) and laboratory results, including the PH, lactate, K+, Ca2+, PO 2 , and PCo 2 (all collected by ABG tests, performed by the cobas® b 123, ASIA-CORE CO.LTD, Chengdu, the reference range of items are listed in tables). The Nijmegen Questionnaire is a widely used tool for clinicians to screen patients for hyperventilation syndrome (HVS) based on patient’s subjective feelings, which scores from 16 dimensions, with a maximum of 4 points for each dimension, a score of above 23 out of 64 may confirm a diagnosis of HVS. Interventions The process was conducted under the ambient temperature of 25℃, and all participants were checked and recorded their body temperatures [13]. After the grouping, participants were led to a quiet, separate room, and a researcher took the responsibility of checking their symptoms with the Nijmegen Questionnaire [18] (Appendix 1) while another researcher counted and recorded the time of this period and participant’s respiratory rate per minutes; in the meantime, a nurse conduct the first arterial blood gas (ABG) analysis for participants, and a physician checked the ABG result to re-confirm PHVS by biochemical level. Then, the LFMO group inhaled 3L/minute oxygen with the oxygen mask and breathed freely, and researchers started to count and record the time of this period and the participants’ respiratory rate. During this period, researchers accompanied the participants and continuously evaluated them using the Nijmegen questionnaire. Once participants met the criteria of recovering from the hyperventilation, researchers stopped the time count; then a nurse conducted the second ABG for participants, and a physician checked the result to confirm the participant had recovered from the PHVS; after that, participants were asked to pick a fair number to indicate their feeling of comfort and tolerance of the interventions from one to ten, one means worst, and ten means perfect (Numerical Rating Scale), and to fill out the Anxiety Sensitivity Index (ASI, Consisting of 16 items with a total score ranging from 0 to 64) [6]. The BT group took the same process, but they performed the breath training (relaxed, normal breathing with 15 breath rate/minute) led by researchers face-on-face during this period, rather than 3L/minute oxygen with the oxygen mask. The research team supervises and guides the intervention process to keep it timely, correct, and safeguard the participants. Data analysis Continuous variables are expressed as mean ± SD, categorical variables are expressed as frequencies and percentages, and the independent samples t-test was selected for this study; Welch’s t-test results were used if the variances were not equal, and the Chi-square test was performed to test categorical variables. All tests were performed by the SPSS (version 27.0, IBM Corporation). P-values <0.05 (two-tailed) were considered statistically significant. Results Participant characteristics Forty-five participants (all Asian) completed the study and were included in the analysis (21 for the LFMO group and 24 for the BT group), mainly female (75%, n=33). All demographic characteristics between the two groups are within the reasonable range and have no significant difference (Table 1, 2). Table 1: characteristic data of participants Items BT Group LFMO Group P-value Participants 24 21 Gender 0.344 male 5 7 Female 19 14 Age(year) 24.08±3.76 23.90±4.11 0.880 Weight (Kg) 56.04±8.74 57.71±7.99 0.509 BMI 20.90±1.62 21.32±1.09 0.322 ASI 21.29±4.80 20.52±6.10 0.639 Scores of Nijmegen Questionnaire at admission 25.67±1.83 25.81±1.72 0.790 Body temperature 36.45±0.15 36.44±0.14 0.869 Time from PHVS onset to admission 20.87±6.77 22.23±6.99 0.511 Pre-intervention respiratory rate 34.71±4.94 33.48±3.93 0.104 Main results All participants were diagnosed with PHVS by the 1 st ABG test (Pco 2: 27.35±3.00; 28.78±1.84) and Nijmegen Questionnaire score (25.67±1.83; 25.81±1.72). However, significant differences were measured in the oxygen index (480.22±29.64, 311.01±15.45, p<0.001), Mean breath rate during recovery (19.17±1.74,28.24±2.53, p<0.001), and the LFMO group showed significant advantages in both the length of recovery (22.94±2.81, p<0.001) and comfort/tolerance (5.86±1.24, p<0.001) (Table 3). Table2: Results of the 1 st ABG test Items BT Group LFMO Group Reference range P-value pH 7.47±0.02 7.47±0.01 7.350-7.450 0.135 Pco 2 (mmHg) 27.35±3.00 28.78±1.84 32.0-48.0 0.060 Po 2 (mmHg) 105.07±7.50 105.99±6.01 83.0-108.0 0.655 Oxygen index (OI) (mmHg) 500.33±35.70 504.72±28.62 0.655 So 2 (%) 99.05±0.91 99.00±0.80 94.0-98.0 0.848 Anion gap (AG) (mmol/L) 12.30±1.63 13.05±1.32 10.0-14.0 0.099 Base excess (BE) (mmol/L) -2.15±0.71 -2.02±1.03 -3.0-3.0 0.618 Methemoglobin (MetHb) (%) 0.45±0.22 0.45±0.18 0.0-1.5 0.914 Reduced hemoglobin (HHB) (%) 0.56±0.41 0.43±0.25 0.0-2.9 0.224 Lactate (mmol/L) 1.72±0.23 1.69±0.17 1.0-1.8 0.563 Glucose (mmol/L) 5.33±0.72 5.16±0.52 4.1-5.6 0.370 Oxyhemoglobin (O 2 Hb) (%) 96.90±0.92 97.62±0.73 94.0-98.0 0.006* Carboxyhemoglobin (COHb) (%) 2.27±0.35 2.16±0.29 0.0-3.0 0.290 cHCO3- (mmol/L) 19.49±1.45 19.72±1.78 21.0-28.0 0.633 Buffer bases (BB) (mmol/L) 43.40±2.17 43.26±2.24 45.0-55.0 0.830 Extracellular BE (BEecf) (mmol/L) -3.57±0.61 -3.53±0.79 -2.0-3.0 0.827 Base excess actual (Beact) (mmol/L) -1.43±0.65 -1.65±0.64 -2.0-3.0 0.257 cH+(nmol/L) 33.77±3.47 35.84±3.37 36.0-44.0 0.049* K+(mmol/L) 3.32±0.12 3.33±0.14 3.50-5.10 0.725 Na+(mmol/L) 136.67±3.59 136.41±3.56 136.0-145.0 0.811 CL-(mmol/L) 106.06±4.78 104.67±3.03 98.0-107.0 0.258 Ca2+(mmol/L) 1.03±0.07 1.02±0.05 1.150-1.330 0.588 Total haemoglobin (tHb) (g/dL) 12.53±1.69 13.16±1.00 11.5-17.8 0.136 Hematocrit (Hct) (%) 40.25±4.42 40.35±3.39 36.0-53.0 0.929 Alveolar-arterial oxygen gradient (AaDO2) (mmHg) 8.10±1.71 9.08±1.47 5.0-20.0 0.047* *: p<0.05 Table 3: Results of the 2 nd ABG test and other outcome variables Items BT Group LFMO Group Reference range P-value pH 7.44±0.01 7.44±0.00 7.350-7.450 0.113 Pco 2 (mmHg) 33.12±1.49 33.95±1.31 32.0-48.0 0.055 Po 2 (mmHg) 100.85±6.22 102.63±5.10 83.0-108.0 0.302 Oxygen index (OI) (mmHg) 480.22±29.64 311.01±15.45 <0.001* So 2 (%) 98.53±0.92 98.81±0.81 94.0-98.0 0.281 Anion gap (AG) (mmol/L) 12.53±1.47 13.00±1.23 10.0-14.0 0.254 Base excess (BE) (mmol/L) -2.01±0.89 -2.00±1.02 -3.0-3.0 0.988 Methemoglobin (MetHb) (%) 0.43±0.21 0.45±0.17 0.0-1.5 0.738 Reduced hemoglobin (HHB) (%) 0.50±0.47 0.44±0.26 0.0-2.9 0.589 Lactate (mmol/L) 1.79±0.31 1.70±0.18 1.0-1.8 0.223 Glucose (mmol/L) 5.31±0.71 5.15±0.51 4.1-5.6 0.398 Oxyhemoglobin (O 2 Hb) (%) 97.21±1.11 97.67±0.71 94.0-98.0 0.113 Carboxyhemoglobin (COHb) (%) 2.30±0.33 2.15±0.28 0.0-3.0 0.097 cHCO3- (mmol/L) 19.83±1.57 19.60±1.69 21.0-28.0 0.639 Buffer bases (BB) (mmol/L) 43.59±2.05 43.22±2.28 45.0-55.0 0.576 Extracellular BE (BEecf) (mmol/L) -3.56±0.63 -3.52±0.78 -2.0-3.0 0.825 Base excess actual (Beact) (mmol/L) -1.43±0.67 -1.68±0.63 -2.0-3.0 0.196 cH+(nmol/L) 34.36±3.53 35.82±3.35 36.0-44.0 0.164 K+(mmol/L) 3.57±0.16 3.56±0.10 3.50-5.10 0.801 Na+(mmol/L) 136.43±3.43 136.74±1.33 136.0-145.0 0.696 CL-(mmol/L) 105.31±4.57 103.96±3.18 98.0-107.0 0.263 Ca2+(mmol/L) 1.10±0.06 1.10±0.05 1.150-1.330 0.998 Total haemoglobin (tHb) (g/dL) 12.78±1.96 13.15±1.01 11.5-17.8 0.432 Hematocrit (Hct) (%) 42.20±3.57 40.40±3.34 36.0-53.0 0.089 Alveolar-arterial oxygen gradient (AaDO2) (mmHg) 8.74±0.84 9.15±1.37 5.0-20.0 0.221 Comfort/tolerance 4.88±1.19 5.86±1.24 0.010* Length of recovery 27.66±2.09 22.94±2.81 <0.001* Scores of the Nijmegen Questionnaire (at the 15 th minute of intervention) 24.17±0.96 23.86±0.65 0.221 Scores of the Nijmegen Questionnaire (at the end) 18.96±1.60 18.62±1.77 0.504 Mean breath rate during recovery 19.17±1.74 28.24±2.53 <0.001* *: p20 minutes) without somatic causes, while the Nijmegen Questionnaire scored more than 23 out of 64, or by an ABG test with a pH more than 7.45 and Pco2 < 32mmHg. Breath training (BT) therapy is a popularized treatment or healthcare exercise for types of HVS, including PHVS, although a Cochrane review doubted its usefulness and effectiveness [8, 10, 12]. To our knowledge, this study is the first to apply LFMO to treating PHVS, which provides a new way to treat PHVS and also identifies some new features of PHVS. Compared to the BT group, the LFMO group showed a remarkable recovery speed of 22.94±2.81 minutes, while the BT group needed 27.66±2.09 minutes. As a type of hyperventilation with unclear etiology [1, 2, 10], PHVS is more likely present in people with panic or anxiety history as well as higher ASI scores [6, 5, 12, 13], which could make BT more complex to implement; In this study, although each patient underwent BT (relaxed, normal breathing with a respiratory rate of 15 breaths/minute) led one-on-one by the researcher, the mean respiratory rate of the group was still 19.17±1.74 breaths/minute, which indicating that the BT may be more difficult for patients to follow in an actual clinical situation. By contrast, the LFMO group inhaled 3L/minute oxygen by an oxygen mask and breathed freely, presenting a much higher mean breath rate (28.24±2.53 breaths/minute) with a much shorter recovery length, which indicates that increased CO2 reabsorption through LFMO rather than control the patients’ respiratory pattern is a more effective way for treating PHVS. Another significant advantage of the LFMO group is the comfort/tolerance score (5.86±1.24) higher than the BT group (4.88±1.19). Considering the fear, paralysis, dizziness, and breathlessness caused by PHVS [1, 2, 12, 14, 18], LFMO uses a simple device to perform the treatment with stable effects, and the low-flow oxygen in the mask during the treatment may also comfort patients and soothe their psychological burden [4], while the BT therapy relies more on patient subjective cooperation and requires patients to actively control their breathing rate despite their fear, which may account for the feeling difference. Although the ABG test detected no significant difference in secondary outcomes in this study, as lactate and ion change correlate with PHVS duration [1], considering the LFMO has a shorter recovery time and the BT may need more time in the clinical setting, we hypothesize that LFMO may have an advantage in keeping stable lactate and ion level which would be tested in future. Additionally, this study also detected the increased lactate level and Potassium decrease during PHVS, which aligns with Avest et al. (2011), but we also found a calcium level change, which has not been mentioned by Avest et al. (2011), which is recommended for more investigation. The oxygen index is an index that reflects lung function and is calculated by the ABG test machine (PaO2/FIO2) with a reasonable range of 400-500. Before the 1 st ABG test, patients inhaled too much oxygen from the air because of the PHVS, leading to a high PaO2; however, during the intervention, the LFMO group inhaled 3 L of oxygen/minute while the BT group did not, which resulted in a difference in oxygen index between the two groups and also resulted in a difference in the oxygen index of the LFMO group at the time of the two ABG tests. This also shows that the oxygen index sometimes does not accurately reflect a subject's lung function and needs to be viewed with caution. Besides, the LFMO ranked lower scores on the Nijmegen Questionnaire at the 15 th minute of intervention; however, the difference is too slight to present a significant difference (p=0.221), so it is not clear whether the LFMO group has a recovery speed advantage in the first 15 minutes, and more often ABG test would undoubtedly be warranted for future studies. Limitation Firstly, PHVS is a disease closely related to subjective feelings. Informing patients of the symptoms of PHVS due to ethical requirements may reduce their fears and impact the experiment results [12]. Secondly, while the sample size met the requirements of the experiment, a larger sample size would undoubtedly increase the validity of this study. Conclusion Compared to breath training therapy, the low-flow mask oxygenation is a more effective, comfortable, and easy-to-follow treatment for PHVS. Abbreviations ED: Emergency department BT: Breath training LFMO: Low-flow mask oxygenation PHVS: Psychogenic hyperventilation syndrome ASI: Anxiety Sensitivity Index ABG: Arterial blood gas Declarations Availability of data and materials The datasets generated and analyzed in this study are not publicly available due protect patient privacy but are available from the corresponding author on reasonable request. Consent for publication Not applicable Funding None Ethics approval and consent to participate The study followed the Sex and Gender Equity in Research (SAGER) guidelines and is in line with the Declaration of Helsinki. Participants can freely withdraw from the study without any effect, which is registered in the Chinese Clinical Trial Registry with a definite number ChiCTR2300072044 and approved by the Ethics Committee of (REDACT) (GYZXLL2023070). All participants voluntarily signed the informed consent by themselves or relatives. All data from this study are confidential and supervised by the Ethics Committee of (REDACT). Authors’ contributions LHY and DMY: conception, design, the analytical plan, and contributed equally to this work. YYL: data acquisition and data analysis. XLZ: critical revision of the manuscript for important intellectual content. ZYL :manuscript drafting Conflict of interest statement The authors declare that they have no competing interests. Data Sharing No additional data are available. Acknowledgment: None References Avest E, Patist FM, Maaten JC, et al. Elevated lactate during psychogenic hyperventilation. Emergency Medicine Journal . 2011; 28 : 269–273. Boulding R, Stacey R, Niven R, et al. Dysfunctional breathing: A review of the literature and proposal for classification. European Respiratory Review . 2016; 25 :287–294. Brussee P, Zwaag J, van Eijk L, et al. Stewart analysis unmasks acidifying and alkalizing effects of ionic shifts during acute severe respiratory alkalosis. 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Hyperventilation Syndrome: Investigating the Relationship Between Nijmegen Questionnaire, Vestibular Function Tests, and Patient Symptoms. Otology & Neurotology: Official Publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology . 2020; 41 : e349–e356. 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-5720282","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":403001206,"identity":"40197af0-bd54-4bb3-a2c9-f96d5f12ccf6","order_by":0,"name":"Linhe Yang","email":"","orcid":"","institution":"Guangyuan central hospital Guangyuan","correspondingAuthor":false,"prefix":"","firstName":"Linhe","middleName":"","lastName":"Yang","suffix":""},{"id":403001207,"identity":"eb8e7509-366f-422a-9ba3-7e7b1e8de45d","order_by":1,"name":"Dongmei Yuan","email":"","orcid":"","institution":"West China Hospital of Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Dongmei","middleName":"","lastName":"Yuan","suffix":""},{"id":403001208,"identity":"38a7bdfb-23e8-46a0-a096-cecec1ffaad6","order_by":2,"name":"Zhenyu Luo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAz0lEQVRIiWNgGAWjYBAC+4bDBx98MPgvZ3+8gUgtBozHkg1nFDAbM5w5QKwW5jNm0jwfmBMbbiQQqcWc7YyBNI8BmzHjzMcbbzDU2EQT1GLZc6zAcI4BjxyzdFqxBcOxtNwGgnpuHN6Q8MZAwphNOsdMgrHhMBFa7j8wOMBjYJDYI3mGSC0GB44YNvIYJCTOkOAhUotkw7FkxhkGB4wNeIB+SSDGL/wMh4//+PDngJwB++GNNz7U2BDhF2RHSiSQohyihVQdo2AUjIJRMDIAAA1pQ7+BsiqcAAAAAElFTkSuQmCC","orcid":"","institution":"Guangyuan central hospital Guangyuan","correspondingAuthor":true,"prefix":"","firstName":"Zhenyu","middleName":"","lastName":"Luo","suffix":""},{"id":403001209,"identity":"339218f9-26aa-4a4d-bd15-f900330d4170","order_by":3,"name":"Yunying Li","email":"","orcid":"","institution":"Guangyuan central hospital Guangyuan","correspondingAuthor":false,"prefix":"","firstName":"Yunying","middleName":"","lastName":"Li","suffix":""},{"id":403001210,"identity":"10931624-2828-402f-9802-baec52a5bdfb","order_by":4,"name":"Xiuli Zhu","email":"","orcid":"","institution":"First People's Hospital of Zigong City","correspondingAuthor":false,"prefix":"","firstName":"Xiuli","middleName":"","lastName":"Zhu","suffix":""}],"badges":[],"createdAt":"2024-12-27 08:53:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5720282/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5720282/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":74076609,"identity":"4b849357-f434-4c2c-a54e-a30e2405047f","added_by":"auto","created_at":"2025-01-17 13:42:45","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":241740,"visible":true,"origin":"","legend":"\u003cp\u003eThe CONSORT flowchart.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-5720282/v1/cf413a9dd3f5db0423f16c4a.png"},{"id":76456201,"identity":"737d912d-6252-4b58-9341-50de32aa8410","added_by":"auto","created_at":"2025-02-17 10:38:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":851678,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5720282/v1/91ec0d36-5639-4611-a4a6-69859b6879a4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eThe low-flow mask oxygen is a more effective, comfortable, and easy-to-follow treatment for psychogenic hyperventilation syndrome: a double-blind, randomized controlled trial\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePsychogenic hyperventilation is common in emergency departments (ED) worldwide, which has been defined as \u0026ldquo;respiratory rate (\u0026gt;20 minutes) increased at or before the ED visit, and can not be explained by somatic causes [1]\u0026rdquo;, people inhale oxygen and exhale carbon dioxide too much in a short period, and some of them could be aggravated into Psychogenic hyperventilation syndrome (PHVS) [2, 3, 15] and finally result in emergency visits [1, 5, 13, 14].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor its easy-to-use and non-invasive features [8, 10, 12], breath training (BT) has long attracted physicians\u0026rsquo; attention and has become the most-using treatment for psychogenic hyperventilation syndrome (PHVS). However, the PHVS could result in a series of uncomfortable physical feelings, including breath shortness, tingling fingers, chest pain, etc., then provoke psychological symptoms such as anxiety, fear, and even panic disorder [5, 9, 12, 13, 14, 16], causing the patient to believe that they are lacking in oxygen falsely, thus speeding up breathing and falling into a vicious circle; by this way, it could never be easy for medical staffs to calm and teach patients to adjust their breath mode in ED practice. Although a Cochrane evidence-based review has questioned the effectiveness of breath training and called for a new, safe treatment [10], existing studies have still focused on studying the effects of BT with some methodological limitations acknowledged by the authors themselves, such as relying on participants\u0026rsquo; self-report symptoms, lack of convincing standards to diagnose the PHVS [5, 8, 10, 17], besides, as more PHVS related factors emerged through new studies, such as ambient temperature [13], further undermining the credibility of previous studies, a study for new safe treatment is urgent.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eInspired by the Chinese expert consensus on ED oxygen treatment [7], which mentioned that oxygen masks with low oxygen flow (\u0026lt;5L/minute) could lead to carbon dioxide rebreathing. We hypothesize that using oxygen masks with oxygen flow \u0026lt;5L/minute could be a better treatment for PHVS in the ED setting, as the physiological changes opposite to PHVS and the use of medical equipment and oxygen supply could psychologically calm the patients.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObjectives of this study\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study compares the effect of low-flow mask oxygenation (LFMO) with breathing training (BT) for psychogenic hyperventilation syndrome (PHVS), providing more options and evidence for clinical treatment.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e\u003cstrong\u003eStudy design and setting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA randomized double-blinded controlled experiment was registered in the Chinese Clinical Trial Registry on 01/06/2023 with a defined number (ChiCTR2300072044) and approved by the Ethics Committee of (REDACT) (GYZXLL2023070) and then conducted in there from 10 May 2024 to 23 November 2024, which is the region\u0026apos;s largest referral, medical, and teaching center was certificated with the national trauma center, chest pain center, and Stroke center in 2016, 2018, and 2019 separately, it consists of two hospital areas, treating over 20000 emergency visits annually. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eParticipants recruiting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe sample size calculation for this study was based on the pilot study with 24 volunteers [11], in which the mean duration from diagnosing PHVS to recovery was 27.6\u0026plusmn;2.3 minutes in the breath training group (BT group) and 21.4\u0026plusmn;2.5 minutes in the low-flow mask oxygenation group (LFMO group). Assuming \u0026alpha; = 0.05 (two-tailed) and 1-\u0026beta;=90% for this study, 18 study subjects were required in each group, and considering a 10% shedding rate, 20 study subjects had to be recruited in each group, making a total of 40 cases in both groups. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePatients who met the following criteria were recruited, and informed consent was obtained from the participants or next to kin: (1) Inclusion criteria: (i) age \u0026ge;18 years; (ii) diagnosed as PHVS and reconfirmed by arterial blood gas analysis and the Nijmegen Questionnaire; (iii)voluntary participation in this study; (2) Exclusion criteria: (i) having a history of significant organic pathology or respiratory disease; (ii) coagulation disorders; (iii) have the presence of PHVS before; (iiii) presence of factors that may cause carbon dioxide retention (e.g., BMI\u0026ge;25, chest trauma) [7]; (v) communication disorders; (vi) abnormal body temperature (＜36℃ or \u0026ge;37.3 ℃). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRandomization and blinding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA simple randomized grouping method was conducted, where the participants blindly drew a unique number, and then the project leader used a computer program to divide all numbers equally to LFMO and BT groups randomly. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe project leader is responsible for the participants\u0026rsquo; recruitment, random grouping, and keeping information. The other researchers who performed the intervention were not informed of their assignment to groups, nor were they informed of the difference between the two interventions; they were not allowed to communicate with the rest of the participants throughout the experiment to avoid disclosure of the grouping. The participants were informed of the purpose of the study, the procedures, and the possible symptoms of the study before the start of the experiment but were not informed of their assignment to the experimental group or the control group, nor were they informed of the differences between the two groups; they were asked to remain strictly confidential throughout the experiment and were not allowed to communicate with the rest of the participants to minimize implementation bias. The two groups conducted interventions separately, and each participant was accompanied by two researchers who were responsible for the intervention (figure 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eVariables and measurement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGender, age, weight, BMI, ASI, the Nijmegen Questionnaire scores at admission, body temperature, time from PHVS onset to admission, and mean pre-intervention respiratory rate (Calculated by dividing the total number of breaths from grouping to intervention by time) were collected as the characteristic data. The recovery length from PHVS, the Nijmegen Questionnaire score at fifteen minutes since the intervention, the Nijmegen Questionnaire score at the end of the intervention, and the comfort/tolerance score (participant rating via NRS) were collected as the primary outcome. The secondary outcome was measured by the mean breath rate during the recovery (Calculated by dividing the total number of breaths during the intervention by time) and laboratory results, including the PH, lactate, K+, Ca2+, PO\u003csub\u003e2\u003c/sub\u003e, and PCo\u003csub\u003e2\u003c/sub\u003e (all collected by ABG tests, performed by the cobas\u0026reg; b 123, ASIA-CORE CO.LTD, Chengdu, the reference range of items are listed in tables). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe Nijmegen Questionnaire is a widely used tool for clinicians to screen patients for hyperventilation syndrome (HVS) based on patient\u0026rsquo;s subjective feelings, which scores from 16 dimensions, with a maximum of 4 points for each dimension, a score of above 23 out of 64 may confirm a diagnosis of HVS.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInterventions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe process was conducted under the ambient temperature of 25℃, and all participants were checked and recorded their body temperatures [13]. After the grouping, participants were led to a quiet, separate room, and a researcher took the responsibility of checking their symptoms with the Nijmegen Questionnaire [18] (Appendix 1) while another researcher counted and recorded the time of this period and participant\u0026rsquo;s respiratory rate per minutes; in the meantime, a nurse conduct the first arterial blood gas (ABG) analysis for participants, and a physician checked the ABG result to re-confirm PHVS by biochemical level. Then, the LFMO group inhaled 3L/minute oxygen with the oxygen mask and breathed freely, and researchers started to count and record the time of this period and the participants\u0026rsquo; respiratory rate. During this period, researchers accompanied the participants and continuously evaluated them using the Nijmegen questionnaire. Once participants met the criteria of recovering from the hyperventilation, researchers stopped the time count; then a nurse conducted the second ABG for participants, and a physician checked the result to confirm the participant had recovered from the PHVS; after that, participants were asked to pick a fair number to indicate their feeling of comfort and tolerance of the interventions from one to ten, one means worst, and ten means perfect (Numerical Rating Scale), and to fill out the Anxiety Sensitivity Index (ASI, Consisting of 16 items with a total score ranging from 0 to 64) [6]. The BT group took the same process, but they performed the breath training (relaxed, normal breathing with 15 breath rate/minute) led by researchers face-on-face during this period, rather than 3L/minute oxygen with the oxygen mask. The research team supervises and guides the intervention process to keep it timely, correct, and safeguard the participants.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eContinuous variables are expressed as mean \u0026plusmn; SD, categorical variables are expressed as frequencies and percentages, and the\u0026nbsp;independent samples t-test was selected for this study; Welch\u0026rsquo;s\u003cstrong\u003e\u0026nbsp;t-test\u003c/strong\u003e results were used if the variances were not equal, and the Chi-square test was performed to test categorical variables. All tests were performed by the SPSS (version 27.0, IBM Corporation). P-values \u0026lt;0.05 (two-tailed) were considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eParticipant characteristics\u003c/p\u003e\n\u003cp\u003eForty-five participants (all Asian) completed the study and were included in the analysis (21 for the LFMO group and 24 for the BT group), mainly female (75%, n=33). All demographic characteristics between the two groups are within the reasonable range and have no significant difference (Table 1, 2).\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 1: characteristic data of participants\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eItems\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003eBT Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003eLFMO Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eParticipants\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e21\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eGender\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.344\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003emale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003e\u0026nbsp; Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eAge(year)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e24.08\u0026plusmn;3.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e23.90\u0026plusmn;4.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.880\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eWeight (Kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e56.04\u0026plusmn;8.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e57.71\u0026plusmn;7.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.509\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eBMI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e20.90\u0026plusmn;1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e21.32\u0026plusmn;1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.322\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eASI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e21.29\u0026plusmn;4.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e20.52\u0026plusmn;6.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.639\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eScores of Nijmegen Questionnaire at admission\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e25.67\u0026plusmn;1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e25.81\u0026plusmn;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.790\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eBody temperature\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e36.45\u0026plusmn;0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e36.44\u0026plusmn;0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.869\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003eTime from PHVS onset to admission\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e20.87\u0026plusmn;6.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e22.23\u0026plusmn;6.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.511\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 34.3478%;\"\u003e\n \u003cp\u003ePre-intervention respiratory rate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e34.71\u0026plusmn;4.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 22.3913%;\"\u003e\n \u003cp\u003e33.48\u0026plusmn;3.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.8696%;\"\u003e\n \u003cp\u003e0.104\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eMain results\u003c/p\u003e\n\u003cp\u003eAll participants were diagnosed with PHVS by the 1\u003csup\u003est\u003c/sup\u003e ABG test (Pco\u003csub\u003e2:\u0026nbsp;\u003c/sub\u003e27.35\u0026plusmn;3.00; 28.78\u0026plusmn;1.84) and Nijmegen Questionnaire score (25.67\u0026plusmn;1.83; 25.81\u0026plusmn;1.72). However, significant differences were measured in the oxygen index (480.22\u0026plusmn;29.64, 311.01\u0026plusmn;15.45, p\u0026lt;0.001), Mean breath rate during recovery (19.17\u0026plusmn;1.74,28.24\u0026plusmn;2.53, p\u0026lt;0.001), and the LFMO group showed significant advantages in both the length of recovery (22.94\u0026plusmn;2.81, p\u0026lt;0.001) and comfort/tolerance (5.86\u0026plusmn;1.24, p\u0026lt;0.001) (Table 3).\u003c/p\u003e\n\u003cp\u003eTable2: Results of the 1\u003csup\u003est\u003c/sup\u003e ABG test\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eItems\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003eBT Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003eLFMO Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003eReference range\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003epH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e7.47\u0026plusmn;0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e7.47\u0026plusmn;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e7.350-7.450\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.135\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ePco\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e27.35\u0026plusmn;3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e28.78\u0026plusmn;1.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e32.0-48.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.060\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ePo\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e105.07\u0026plusmn;7.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e105.99\u0026plusmn;6.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e83.0-108.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.655\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eOxygen index (OI)\u003csub\u003e\u0026nbsp;\u003c/sub\u003e(mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e500.33\u0026plusmn;35.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e504.72\u0026plusmn;28.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.655\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eSo\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e99.05\u0026plusmn;0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e99.00\u0026plusmn;0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e94.0-98.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.848\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eAnion gap (AG) (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e12.30\u0026plusmn;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e13.05\u0026plusmn;1.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e10.0-14.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.099\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eBase excess (BE)\u0026nbsp;(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-2.15\u0026plusmn;0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-2.02\u0026plusmn;1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e-3.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.618\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eMethemoglobin (MetHb) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.45\u0026plusmn;0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.45\u0026plusmn;0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e0.0-1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.914\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eReduced hemoglobin (HHB) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.56\u0026plusmn;0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.43\u0026plusmn;0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e0.0-2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.224\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eLactate (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.72\u0026plusmn;0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.69\u0026plusmn;0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e1.0-1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.563\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eGlucose (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e5.33\u0026plusmn;0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e5.16\u0026plusmn;0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e4.1-5.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.370\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eOxyhemoglobin (O\u003csub\u003e2\u003c/sub\u003eHb) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e96.90\u0026plusmn;0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e97.62\u0026plusmn;0.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e94.0-98.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.006*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eCarboxyhemoglobin (COHb) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e2.27\u0026plusmn;0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e2.16\u0026plusmn;0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e0.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.290\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ecHCO3- (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e19.49\u0026plusmn;1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e19.72\u0026plusmn;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e21.0-28.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.633\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eBuffer bases (BB)\u0026nbsp;(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e43.40\u0026plusmn;2.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e43.26\u0026plusmn;2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e45.0-55.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.830\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eExtracellular BE (BEecf) (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-3.57\u0026plusmn;0.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-3.53\u0026plusmn;0.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e-2.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.827\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eBase excess actual (Beact) (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-1.43\u0026plusmn;0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-1.65\u0026plusmn;0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e-2.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.257\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ecH+(nmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e33.77\u0026plusmn;3.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e35.84\u0026plusmn;3.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e36.0-44.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.049*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eK+(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e3.32\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e3.33\u0026plusmn;0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e3.50-5.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.725\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eNa+(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e136.67\u0026plusmn;3.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e136.41\u0026plusmn;3.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e136.0-145.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.811\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eCL-(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e106.06\u0026plusmn;4.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e104.67\u0026plusmn;3.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e98.0-107.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.258\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eCa2+(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.03\u0026plusmn;0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.02\u0026plusmn;0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e1.150-1.330\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.588\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eTotal haemoglobin (tHb) (g/dL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e12.53\u0026plusmn;1.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e13.16\u0026plusmn;1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e11.5-17.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.136\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eHematocrit (Hct) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e40.25\u0026plusmn;4.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e40.35\u0026plusmn;3.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e36.0-53.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.929\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eAlveolar-arterial oxygen gradient (AaDO2) (mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e8.10\u0026plusmn;1.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e9.08\u0026plusmn;1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e5.0-20.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.047*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*: p\u0026lt;0.05\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3: Results of the 2\u003csup\u003end\u003c/sup\u003e ABG test and other outcome variables\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eItems\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003eBT Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003eLFMO Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003eReference range\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003epH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e7.44\u0026plusmn;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e7.44\u0026plusmn;0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e7.350-7.450\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ePco\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e33.12\u0026plusmn;1.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e33.95\u0026plusmn;1.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e32.0-48.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.055\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ePo\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e100.85\u0026plusmn;6.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e102.63\u0026plusmn;5.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e83.0-108.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.302\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eOxygen index (OI)\u003csub\u003e\u0026nbsp;\u003c/sub\u003e(mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e480.22\u0026plusmn;29.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e311.01\u0026plusmn;15.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eSo\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e98.53\u0026plusmn;0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e98.81\u0026plusmn;0.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e94.0-98.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.281\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eAnion gap (AG) (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e12.53\u0026plusmn;1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e13.00\u0026plusmn;1.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e10.0-14.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.254\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eBase excess (BE)\u0026nbsp;(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-2.01\u0026plusmn;0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-2.00\u0026plusmn;1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e-3.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.988\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eMethemoglobin (MetHb) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.43\u0026plusmn;0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.45\u0026plusmn;0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e0.0-1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.738\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eReduced hemoglobin (HHB) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.50\u0026plusmn;0.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e0.44\u0026plusmn;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e0.0-2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.589\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eLactate (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.79\u0026plusmn;0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.70\u0026plusmn;0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e1.0-1.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.223\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eGlucose (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e5.31\u0026plusmn;0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e5.15\u0026plusmn;0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e4.1-5.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.398\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eOxyhemoglobin (O\u003csub\u003e2\u003c/sub\u003eHb) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e97.21\u0026plusmn;1.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e97.67\u0026plusmn;0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e94.0-98.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eCarboxyhemoglobin (COHb) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e2.30\u0026plusmn;0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e2.15\u0026plusmn;0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e0.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.097\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ecHCO3- (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e19.83\u0026plusmn;1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e19.60\u0026plusmn;1.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e21.0-28.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.639\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eBuffer bases (BB)\u0026nbsp;(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e43.59\u0026plusmn;2.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e43.22\u0026plusmn;2.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e45.0-55.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.576\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eExtracellular BE (BEecf) (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-3.56\u0026plusmn;0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-3.52\u0026plusmn;0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e-2.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.825\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eBase excess actual (Beact) (mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-1.43\u0026plusmn;0.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e-1.68\u0026plusmn;0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e-2.0-3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.196\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003ecH+(nmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e34.36\u0026plusmn;3.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e35.82\u0026plusmn;3.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e36.0-44.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.164\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eK+(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e3.57\u0026plusmn;0.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e3.56\u0026plusmn;0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e3.50-5.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.801\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eNa+(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e136.43\u0026plusmn;3.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e136.74\u0026plusmn;1.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e136.0-145.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.696\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eCL-(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e105.31\u0026plusmn;4.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e103.96\u0026plusmn;3.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e98.0-107.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.263\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eCa2+(mmol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.10\u0026plusmn;0.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e1.10\u0026plusmn;0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e1.150-1.330\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eTotal haemoglobin (tHb) (g/dL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e12.78\u0026plusmn;1.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e13.15\u0026plusmn;1.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e11.5-17.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.432\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eHematocrit (Hct) (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e42.20\u0026plusmn;3.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e40.40\u0026plusmn;3.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e36.0-53.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.089\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eAlveolar-arterial oxygen gradient (AaDO2) (mmHg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e8.74\u0026plusmn;0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e9.15\u0026plusmn;1.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e5.0-20.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.221\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eComfort/tolerance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e4.88\u0026plusmn;1.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e5.86\u0026plusmn;1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.010*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eLength of recovery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e27.66\u0026plusmn;2.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e22.94\u0026plusmn;2.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eScores of the Nijmegen Questionnaire (at the 15\u003csup\u003eth\u003c/sup\u003e minute of intervention)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e24.17\u0026plusmn;0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e23.86\u0026plusmn;0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.221\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eScores of the Nijmegen Questionnaire (at the end)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e18.96\u0026plusmn;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e18.62\u0026plusmn;1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e0.504\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 30.3249%;\"\u003e\n \u003cp\u003eMean breath rate during recovery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e19.17\u0026plusmn;1.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18.4116%;\"\u003e\n \u003cp\u003e28.24\u0026plusmn;2.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.2455%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.6065%;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e*: p\u0026lt;0.05\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePsychogenic hyperventilation syndrome patients present high respiratory rate (\u0026gt;20 minutes) without somatic causes, while the Nijmegen Questionnaire scored more than 23 out of 64, or by an ABG test with a pH more than 7.45 and Pco2 \u0026lt; 32mmHg. Breath training (BT) therapy is a popularized treatment or healthcare exercise for types of HVS, including PHVS, although a Cochrane review doubted its usefulness and effectiveness [8, 10, 12]. To our knowledge, this study is the first to apply LFMO to treating PHVS, which provides a new way to treat PHVS and also identifies some new features of PHVS.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCompared to the BT group, the LFMO group showed a remarkable recovery speed of 22.94\u0026plusmn;2.81 minutes, while the BT group needed 27.66\u0026plusmn;2.09 minutes. As a type of hyperventilation with unclear etiology [1, 2, 10], PHVS is more likely present in people with panic or anxiety history as well as higher ASI scores [6, 5, 12, 13], which could make BT more complex to implement; In this study, although each patient underwent BT (relaxed, normal breathing with a respiratory rate of 15 breaths/minute) led one-on-one by the researcher, the mean respiratory rate of the group was still 19.17\u0026plusmn;1.74 breaths/minute, which indicating that the BT may be more difficult for patients to follow in an actual clinical situation. By contrast, the LFMO group inhaled 3L/minute oxygen by an oxygen mask and breathed freely, presenting a much higher mean breath rate (28.24\u0026plusmn;2.53 breaths/minute) with a much shorter recovery length, which indicates that increased CO2 reabsorption through LFMO rather than control the patients\u0026rsquo; respiratory pattern is a more effective way for treating PHVS. Another significant advantage of the LFMO group is the comfort/tolerance score (5.86\u0026plusmn;1.24) higher than the BT group (4.88\u0026plusmn;1.19). Considering the fear, paralysis, dizziness, and breathlessness caused by PHVS [1, 2, 12, 14, 18], LFMO uses a simple device to perform the treatment with stable effects, and the low-flow oxygen in the mask during the treatment may also comfort patients and soothe their psychological burden [4], while the BT therapy relies more on patient subjective cooperation and requires patients to actively control their breathing rate despite their fear, which may account for the feeling difference. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAlthough the ABG test detected no significant difference in secondary outcomes in this study, as lactate and ion change correlate with PHVS duration [1], considering the LFMO has a shorter recovery time and the BT may need more time in the clinical setting, we hypothesize that LFMO may have an advantage in keeping stable lactate and ion level which would be tested in future. Additionally, this study also detected the increased lactate level and Potassium decrease during PHVS, which aligns with Avest et al. (2011), but we also found a calcium level change, which has not been mentioned by Avest et al. (2011), which is recommended for more investigation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe oxygen index is an index that reflects lung function and is calculated by the ABG test machine (PaO2/FIO2) with a reasonable range of 400-500. Before the 1\u003csup\u003est\u003c/sup\u003e ABG test, patients inhaled too much oxygen from the air because of the PHVS, leading to a high PaO2; however, during the intervention, the LFMO group inhaled 3 L of oxygen/minute while the BT group did not, which resulted in a difference in oxygen index between the two groups and also resulted in a difference in the oxygen index of the LFMO group at the time of the two ABG tests. This also shows that the oxygen index sometimes does not accurately reflect a subject\u0026apos;s lung function and needs to be viewed with caution. Besides, the LFMO ranked lower scores on the Nijmegen Questionnaire at the 15\u003csup\u003eth\u003c/sup\u003e minute of intervention; however, the difference is too slight to present a significant difference (p=0.221), so it is not clear whether the LFMO group has a recovery speed advantage in the first 15 minutes, and more often ABG test would undoubtedly be warranted for future studies.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLimitation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFirstly, PHVS is a disease closely related to subjective feelings. Informing patients of the symptoms of PHVS due to ethical requirements may reduce their fears and impact the experiment results [12]. Secondly, while the sample size met the requirements of the experiment, a larger sample size would undoubtedly increase the validity of this study.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eCompared to breath training therapy, the low-flow mask oxygenation is a more effective, comfortable, and easy-to-follow treatment for PHVS.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eED: Emergency department \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBT: Breath training\u003c/p\u003e\n\u003cp\u003eLFMO: Low-flow mask oxygenation\u003c/p\u003e\n\u003cp\u003ePHVS: Psychogenic hyperventilation\u0026nbsp;syndrome\u003c/p\u003e\n\u003cp\u003eASI: Anxiety Sensitivity Index\u003c/p\u003e\n\u003cp\u003eABG: Arterial blood gas\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed in this study are not publicly available due protect patient privacy but are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study followed the Sex and Gender Equity in Research (SAGER) guidelines and is in line with the Declaration of Helsinki. Participants can freely withdraw from the study without any effect, which is registered in the Chinese Clinical Trial Registry with a definite number ChiCTR2300072044 and approved by the Ethics Committee of (REDACT) (GYZXLL2023070). All participants voluntarily signed the informed consent by themselves or relatives. All data from this study are confidential and supervised by the Ethics Committee of (REDACT).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLHY and DMY: conception, design, the analytical plan, and contributed equally to this work. YYL: data acquisition and data analysis. XLZ: critical revision of the manuscript for important intellectual content. ZYL :manuscript drafting\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Sharing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo additional data are available. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAvest E, Patist FM, Maaten JC, et al. Elevated lactate during psychogenic hyperventilation. \u003cem\u003eEmergency Medicine Journal\u003c/em\u003e. 2011;\u003cem\u003e28\u003c/em\u003e: 269\u0026ndash;273.\u003c/li\u003e\n \u003cli\u003eBoulding R, Stacey R, Niven R, et al. 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Primary Hyperventilation in the Emergency Department: A First Overview. \u003cem\u003ePloS One\u003c/em\u003e. 2015;\u003cem\u003e10\u003c/em\u003e: e0129562.\u003c/li\u003e\n \u003cli\u003eSep\u0026uacute;lveda RA, Romero J, Sep\u0026uacute;lveda S, et al. Severe respiratory alkalosis due to psychogenic hyperventilation. Report of one case. \u003cem\u003eRevista Medica De Chile\u003c/em\u003e. 2022; \u003cem\u003e150\u003c/em\u003e: 554\u0026ndash;558.\u003c/li\u003e\n \u003cli\u003eTunnell, N. C., Ritz, T., Wilhelm, F. H., Roth, W. T., \u0026amp; Meuret, A. E. (2021). Habituation or Normalization? Experiential and Respiratory Recovery From Voluntary Hyperventilation in Treated Versus Untreated Patients With Panic Disorder. \u003cem\u003eBehavior Therapy\u003c/em\u003e, \u003cem\u003e52\u003c/em\u003e(1), 124\u0026ndash;135. https://doi.org/10.1016/j.beth.2020.03.003\u003c/li\u003e\n \u003cli\u003eWatson GM, Sutherland J, Lacey C, et al. A randomized cross-over trial of QT response to hyperventilation-induced anxiety and diaphragmatic breathing in patients with stress cardiomyopathy and in control patients. \u003cem\u003ePloS One\u003c/em\u003e. 2022; \u003cem\u003e17\u003c/em\u003e: e0265607.\u003c/li\u003e\n \u003cli\u003eWilliams CYK, Williams RWK, Knight R, et al. Hyperventilation Syndrome: Investigating the Relationship Between Nijmegen Questionnaire, Vestibular Function Tests, and Patient Symptoms. \u003cem\u003eOtology \u0026amp; Neurotology: Official Publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology\u003c/em\u003e. 2020; \u003cem\u003e41\u003c/em\u003e: e349\u0026ndash;e356.\u003c/li\u003e\n\u003c/ol\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":"hyperventilation, low-flow oxygen, breath training, psychogenic hyperventilation","lastPublishedDoi":"10.21203/rs.3.rs-5720282/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5720282/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjectives\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo compare the effect of low-flow mask oxygenation (LFMO) with breathing training (BT) for psychogenic hyperventilation syndrome (PHVS), providing more options and evidence for clinical treatment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA randomized double-blinded controlled experiment was registered in the Chinese Clinical Trial Registry on 01/06/2023 with a defined number (ChiCTR2300072044) and approved by the Ethics Committee of (REDACT) (GYZXLL2023070) and then conducted there from 10 May 2024 to 23 November 2024. Participants with PHVS were blindly randomized into the LFMO group and the BT group, then the LFMO group inhaled 3L/minute oxygen with the oxygen mask and breathed freely, while the BT group performed the breath training led by researchers face-on-face. The recovery length from PHVS, the Nijmegen Questionnaire score at fifteen minutes since the intervention, the Nijmegen Questionnaire score at the end of the intervention, and the comfort/tolerance score (participant rating via NRS) were collected as the primary outcome. The secondary outcome was measured by the mean breath rate during the recovery (Calculated by dividing the total number of breaths during the intervention by time) and laboratory results, including the PH, lactate, K+, Ca2+, PO\u003csub\u003e2\u003c/sub\u003e, and PCo\u003csub\u003e2.\u003c/sub\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eForty-five participants (all Asian) completed the study and were included in the analysis (21 for the LFMO group and 24 for the BT group), mainly female (75%, n=33). All demographic characteristics between the two groups are within the reasonable range and have no significant difference. However, significant differences were measured among the outcomes, including the oxygen index (480.22±29.64, 311.01±15.45, p\u0026lt;0.001), Mean breath rate during recovery (19.17±1.74,28.24±2.53, p\u0026lt;0.001), and the LFMO group showed significant advantages in both the length of recovery (22.94±2.81, p\u0026lt;0.001) and comfort/tolerance (5.86±1.24, p\u0026lt;0.001).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCompared to breath training therapy, the low-flow mask oxygenation is a more effective, comfortable, and easy-to-follow treatment for PHVS.\u003c/p\u003e","manuscriptTitle":"The low-flow mask oxygen is a more effective, comfortable, and easy-to-follow treatment for psychogenic hyperventilation syndrome: a double-blind, randomized controlled trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-17 13:42:40","doi":"10.21203/rs.3.rs-5720282/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":"b8ddf89f-6a2d-435d-a302-1eb0b37f34d5","owner":[],"postedDate":"January 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":42995759,"name":"Health sciences/Diseases/Psychiatric disorders"},{"id":42995760,"name":"Health sciences/Diseases/Respiratory tract diseases"},{"id":42995761,"name":"Biological sciences/Physiology/Respiration"}],"tags":[],"updatedAt":"2025-02-17T10:38:13+00:00","versionOfRecord":[],"versionCreatedAt":"2025-01-17 13:42:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5720282","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5720282","identity":"rs-5720282","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}