Temporal and Weight-Related Variations in Chest Compression Quality during CPR: A 30-Second Interval Manikin Study

Temporal and Weight-Related Variations in Chest Compression Quality during CPR: A 30-Second Interval Manikin Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Temporal and Weight-Related Variations in Chest Compression Quality during CPR: A 30-Second Interval Manikin Study Raziyeh Tajik, Rahim Ali Sheikhi, Mohammad Heydari, Hadi Raeisi Shahraki This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7134265/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Background High-quality chest compressions are essential for effective cardiopulmonary resuscitation (CPR). This study aimed to evaluate the influence of rescuer sex and body weight on chest compression quality during the first two minutes, with emphasis on temporal changes within 30-second intervals. Methods In this cross-sectional simulation study, 103 healthcare providers performed three 2-minute cycles of continuous chest compressions on a manikin. Data from all cycles were analyzed; however, only first-cycle results are reported due to performance consistency across cycles. Compression quality was assessed in 30-second intervals, and weight was analyzed both continuously and using a 60-kg cutoff. The ILCOR benchmark of 200–240 compressions per 2 minutes was used for comparison. Results Female participants demonstrated a significant decline in the number of effective compressions (5–6 cm depth) after the first minute (p < 0.001), particularly in the last two intervals, whereas male participants maintained relatively stable performance (p = 0.342). Participants weighing ≥60 kg delivered significantly more effective compressions than those <60 kg (mean: 114.16 vs. 27.34 compressions; p < 0.001). Although total compression counts were higher in heavier participants, this difference was not statistically significant (p = 0.126). Notably, the mean number of effective compressions in all subgroups remained below the ILCOR-recommended range. Conclusion Rescuer sex and body weight significantly influence chest compression quality, especially depth, with females and lighter-weight individuals showing a marked decline after one minute. These findings highlight the need for careful consideration of rotation intervals and suggest that individualized CPR training strategies—accounting for physical characteristics—may improve adherence to guidelines. However, potential trade-offs, such as increased hands-off time from more frequent rescuer changes, should be carefully weighed in clinical practice. Trial registration: Not applicable Trial sponsor: Shahrekord University of Medical Science Funding: This research is financially supported by Shahrekord University of Medical Sciences. Study status: This study has been completed. Related article: No related articles for this study have been submitted to any journal. The study's sponsor and funders had no involvement in the data's design, analysis, or interpretation. The content is entirely the authors' responsibility and does not necessarily reflect the official views of the National Institutes of Health. Cardiopulmonary resuscitation chest compression gender differences body weight healthcare workers CPR quality simulation Introduction Sudden cardiac arrest (SCA) is a leading cause of death globally and constitutes one of the most time-sensitive medical emergencies. The abrupt cessation of effective cardiac activity results in immediate disruption of blood flow to vital organs such as the brain and heart, causing irreversible damage or death if not promptly treated [ 1 ]. Globally, approximately 3.17 million people die annually due to cardiac arrest, with projections expected to exceed 3.26 million by 2030 [ 1 ]. In Iran, SCA also poses a substantial burden on the healthcare system [ 2 ]. High-quality chest compressions are the cornerstone of effective cardiopulmonary resuscitation (CPR) and critically influence patient survival. According to the American Heart Association (AHA) and the International Liaison Committee on Resuscitation (ILCOR) guidelines, optimal chest compressions should reach a depth of 5–6 cm, be delivered at a rate of 100–120 compressions per minute, and involve minimal interruptions [ 3 , 4 ]. The 2015 AHA update, which revised the resuscitation sequence from ABC to CAB, emphasized the importance of promptly initiating and maintaining effective chest compressions [ 4 ]. However, maintaining high-quality chest compressions over time is challenging, particularly due to rescuer fatigue. Prior studies demonstrate a significant decline in compression depth within the first minute of continuous chest compressions, compromising hemodynamic efficacy [ 5 – 7 ]. Although current guidelines recommend rotating rescuers approximately every two minutes to reduce fatigue-related deterioration, this practice is inconsistently applied in clinical settings [ 4 , 8 ]. In addition to fatigue, rescuer physical characteristics—particularly body weight—may affect chest compression quality. Some evidence suggests that individuals with higher body mass may generate more forceful and sustained compressions [ 6 , 7 ]. Nevertheless, few studies have examined the combined effects of time and rescuer physical attributes on compression quality, especially using short, fine-grained temporal intervals within CPR cycles. Considering that body weight distributions vary across populations, and recognizing that simplified cutoff values may not capture all nuances, this study employed a 60 kg threshold—near the sample median and consistent with prior literature indicating mechanical limitations below this weight—for descriptive subgroup analyses. We acknowledge this binary classification’s limitations and emphasize interpretation within the relevant population context. In the Iranian healthcare setting, prior research has highlighted concerns regarding chest compression quality and practical skills among healthcare providers [ 9 ]. Nurses and emergency medical technicians (EMTs), often the first responders in resuscitation, have a vital role in patient outcomes. This study aimed to analyze time-dependent changes in chest compression quality during a 2-minute continuous compression cycle, using 30-second intervals to provide higher temporal resolution. Additionally, it explored the association between rescuer body weight and compression quality. Understanding the timing and extent of performance decline, as well as physical factors influencing chest compression efficacy, can inform tailored training and potentially optimize rotation strategies. However, rotation frequency must balance the benefits of reducing rescuer fatigue with the risks of increased hands-off time, underscoring the need for evidence-based approaches to maintain continuous high-quality compressions. Methods Study Design and Setting This cross-sectional, simulation-based analytical study was conducted in 2023 at Shahrekord University of Medical Sciences (SKUMS), Iran. The primary objective was to assess the quality of chest compressions during the first 2 minutes of cardiopulmonary resuscitation (CPR), focusing specifically on the influence of rescuer sex and body weight. Data collection took place in clinical skills laboratories of Hajar and Kashani Hospitals and affiliated emergency medical services (EMS) training centers. Participants and Sampling Eligible participants included nurses and EMS technicians affiliated with SKUMS. Inclusion criteria were: (1) holding a BSc or MSc in nursing, or a diploma/degree in EMS or operating room technology; (2) at least 6 months of clinical experience; and (3) provision of written informed consent. Individuals with known musculoskeletal or cardiovascular disorders or incomplete data were excluded. Convenience sampling was used. A pilot study involving 15 participants estimated a mean of 180 ± 30 effective chest compressions per 2-minute cycle, which informed the sample size calculation. Sample Size Calculation To detect a difference of ≥ 15 effective compressions from the American Heart Association (AHA) benchmark of 200 compressions, with 80% power and α = 0.05 (two-tailed), a sample size of 98 was calculated using G*Power 3.1. To accommodate potential dropouts, 103 participants were recruited. Body Weight Classification Body weight was measured using a calibrated digital scale prior to testing. For inferential analyses, weight was treated as a continuous variable to preserve statistical power and avoid arbitrary categorization. However, for descriptive and interpretive purposes, participants were divided into two groups using a cutoff of 60 kg. This cutoff was chosen based on the approximate median weight of the sample and prior literature suggesting mechanical limitations in chest compression performance below this threshold. It is acknowledged that this binary classification is a simplified approach and may not fully capture the spectrum of weight-related effects, especially in populations where average body weight varies substantially. Data Collection and Procedure Participants performed three consecutive 2-minute cycles of continuous chest compressions on a Resusci Anne manikin (Laerdal, Norway) placed on a firm surface. A 4-minute rest interval separated each cycle, simulating standard three-person CPR team rotations as recommended by the AHA. This rest interval was intended to minimize fatigue accumulation across cycles. All sessions were video recorded for quality control. Although three cycles were recorded, preliminary mixed-effects analyses showed no statistically significant differences in compression depth or rate across cycles (p > 0.10). Therefore, only data from the first cycle were used for primary analyses. Summary results for cycles 2 and 3 are available in Supplementary Table S1 and S2. To reduce performance bias and simulate real-world conditions, the manikin’s visual feedback system (LED indicators for compression depth) was disabled during testing. Chest compression data were extracted for each 30-second interval (epochs): 0–30, 30–60, 60–90, and 90–120 seconds. Outcomes Primary outcome : Number of effective chest compressions during the first 2-minute cycle. Effective compressions were defined as compressions achieving a depth of 5–6 cm based on Laerdal manikin criteria aligned with AHA guidelines. Secondary outcomes : (1) total number of compressions delivered; (2) number of effective compressions within each 30-second interval. Training and Standardization Before testing, participants underwent a brief refresher training session based on the 2020 AHA Basic Life Support guidelines. They practiced on the same manikin with real-time feedback enabled to standardize skill level. However, during the experimental trials, visual feedback was disabled to mimic actual clinical scenarios and minimize bias. The interval between refresher training and participation was kept under one week to reduce skill decay. Validity and Reliability Data collection tools and procedures were reviewed and approved by a five-member expert panel in emergency medicine and resuscitation science. Video-based scoring of compressions demonstrated excellent inter-rater reliability, with a Cohen’s kappa coefficient of 0.88. Statistical Analysis All analyses were conducted using SPSS version 23.0 (IBM Corp., Armonk, NY, USA) and R software. Descriptive statistics summarized participant characteristics and chest compression performance. A linear mixed-effects regression model examined the association between body weight (continuous) and effective chest compressions across the four 30-second intervals of the first CPR cycle. The model included random intercepts to account for repeated measures within participants and tested interaction terms between body weight and sex to explore effect modification. “Effective compression” was explicitly defined as a compression depth between 5 and 6 cm per Laerdal manikin standards and AHA guidelines. Although data on compression rate, hand position, and chest recoil were collected, the primary focus remained on compression depth and total effective compressions. All model assumptions were checked and met. Statistical significance was set at p < 0.05 (two-tailed). Results Participant Characteristics A total of 103 healthcare professionals affiliated with Shahrekord University of Medical Sciences participated in the study. Among them, 54 (52.4%) were female and 49 (47.6%) were male. Most participants were employed in hospital settings (n = 83, 80.6%), while 20 (19.4%) worked in prehospital emergency medical services (EMS). Regarding professional roles, 93 (90.3%) were nurses and 10 (9.7%) were EMTs. ( Table 1 ) The mean age was 25.32 ± 2.86 years, and the mean work experience was 4.52 ± 3.27 years (range: 0.7–16 years). Participants' weight ranged from 44 to 106 kg, with a mean of 69.83 ± 14.68 kg. Table 1 Participant Demographics and Characteristics Variable Category / Range Value Sex Male / Female 49 (47.6%) / 54 (52.4%) Workplace Hospital / EMS 83 (80.6%) / 20 (19.4%) Profession Nurse / EMT 93 (90.3%) / 10 (9.7%) Age (years) 24–44 25.32 ± 2.86 Work experience (years) 0.7–16 4.52 ± 3.27 Weight (kg) 44–106 69.83 ± 14.68 Chest Compression Performance across Cycles Participants performed three consecutive 2-minute cycles of chest compressions. Analysis using linear mixed-effects models indicated no statistically significant differences in compression depth or rate across the three cycles (p > 0.10), suggesting consistent performance. Therefore, only data from the first cycle were used in the primary analyses to reduce redundancy. Supplementary Tables S1 and S2 provide summary results for cycles 2 and 3. Time-Dependent Decline in Compression Quality Chest compression performance was further analyzed across four consecutive 30-second intervals within the first cycle using a linear mixed-effects regression model. ) Table 2 ) Female participants showed a significant decline in the number of effective compressions over time (mean difference from first to last interval: − 7.09, p < 0.001). Male participants maintained relatively stable effective compression counts over the intervals ( p = 0.342 ). ( Table 3 ) Compression rate declined in both sexes over time, with a more pronounced reduction among females. A significant interaction between time interval and sex was observed ( p < 0.01), indicating a more rapid decline in performance among females. Table 2 Effective Compressions by Time Interval and Sex Interval (sec) Female (Mean ± SD) Male (Mean ± SD) 0–30 13.57 ± 6.5 36.40 ± 10.2 30–60 12.16 ± 5.9 37.63 ± 9.8 60–90 9.92 ± 6.3 36.01 ± 9.4 90–120 6.48 ± 5.1 34.79 ± 9.2 Table 3 Compression Rate by Time Interval and Sex (compressions/min) Interval (sec) Female (Mean ± SD) Male (Mean ± SD) 0–30 40.69 ± 4.8 48.16 ± 6.1 30–60 38.89 ± 5.2 46.32 ± 5.8 60–90 38.25 ± 5.6 45.79 ± 5.4 90–120 35.58 ± 6.1 42.47 ± 6.0 Association between Body Weight and Compression Quality Body weight was analyzed as both a continuous variable and using a 60 kg cutoff. It is noted that the 60 kg threshold may not universally define low weight, and future studies should consider more granular stratification.(Table 4 ) Participants weighing ≥ 60 kg performed more total compressions, though this difference was not statistically significant ( p = 0.126). The number of effective compressions was significantly higher in participants ≥ 60 kg compared to those < 60 kg ( p < 0.001). Table 4 Total and Effective Compressions by Weight Group Weight Group N Mean Total Compressions SD p -value < 60 kg 29 176.93 32.62 — ≥ 60 kg 74 189.49 40.87 0.126 Weight Group N Mean Effective Compressions SD p -value < 60 kg 29 27.34 46.81 — ≥ 60 kg 74 114.16 69.24 < 0.001 Comparison with AHA Benchmark The American Heart Association (AHA) recommends approximately 200 effective compressions per 2-minute cycle. One-sample t -tests were used to compare observed effective compression counts against this benchmark, stratified by sex and weight.( Table 5 ) None of the subgroups met the AHA benchmark. The lowest performance was observed among females weighing < 60 kg. Due to a very small sample size (n = 2), data for males weighing < 60 kg should be interpreted cautiously. Table 5 Comparison of Effective Compressions with AHA Benchmark (200 Compressions per Cycle) Sex Weight Group n Mean Effective Compressions SD t -value p -value Meets AHA? Female < 60 kg 27 22.19 40.55 –23.30 < 0.001 ❌ No Female ≥ 60 kg 27 78.59 55.63 –11.37 < 0.001 ❌ No Male < 60 kg 2 97.00 90.51 –1.61 0.230 ⚠ฏ Insufficient data Male ≥ 60 kg 47 149.06 53.56 –6.65 < 0.001 ❌ No Summary of Key Findings Chest compression quality (in terms of depth and rate) declined significantly during the 2-minute cycle, especially among female participants. Higher body weight was associated with better chest compression quality, with a stronger effect noted in female participants. None of the sex or weight subgroups achieved the AHA-recommended 200 effective compressions per cycle. These findings highlight the need for optimized rescuer rotation strategies that balance fatigue mitigation and minimize interruptions. Discussion This study evaluated the quality of chest compressions over a two-minute cycle using a novel approach analyzing discrete 30-second intervals. This fine-grained temporal analysis is a key strength, providing new insights into the dynamics of rescuer performance over time—a perspective rarely addressed in prior research (11). Our results demonstrated a significant decline in both the number and depth of effective chest compressions among female participants, particularly during the latter half of the cycle. In contrast, male participants maintained relatively stable compression performance throughout the two minutes. Notably, participants weighing less than 60 kg—predominantly females—delivered significantly fewer compressions meeting the guideline-recommended depth (≥ 5 cm). However, it should be noted that the 60 kg threshold may not represent a low body weight in all populations, especially among females. A more detailed analysis of weight distribution within the < 60 kg group could clarify whether the observed effect is driven by very low weights or is consistent across the entire subgroup. Although objective fatigue measurement tools were not employed, the marked reduction in compression quality after the first minute—especially among females and lighter individuals—may indicate declining physical capacity. Prior studies using physiological and self-reported fatigue indices have reported similar patterns, with women showing earlier performance deterioration during continuous compressions (14–16). The 30-second interval analysis further revealed that the third and fourth intervals (after 60 seconds) are critical turning points for compression quality decline. This suggests that the conventional 2-minute rescuer rotation interval may be too long for certain subgroups, particularly women and lighter-weight individuals. However, shortening rotation intervals alone could increase hands-off time and reduce the chest compression fraction (CCF), a critical factor for successful resuscitation. Therefore, alongside shorter rotation cycles, other strategies such as incorporating a dedicated CPR coach—as recommended by recent AHA guidelines—should be considered to maintain compression quality and minimize interruptions (17,18). Another important observation was the discrepancy between compression rate and depth. While male participants, especially those ≥ 60 kg, met or exceeded the recommended rate of ≥ 100 compressions per minute, the number of compressions achieving adequate depth remained below the target of 200 compressions per two-minute cycle. This indicates that meeting compression rate alone does not guarantee high-quality chest compressions. Thus, simultaneous monitoring and emphasis on both compression rate and depth during training and evaluation are essential. Sole reliance on total compression count may overestimate CPR effectiveness if compressions are too shallow to generate sufficient perfusion. Finally, as this study was conducted in a controlled simulation environment, female rescuers may experience even greater physical exhaustion during real emergencies where environmental stressors, emotional factors, and operational challenges further impair performance. These results highlight the need for gender- and weight-sensitive training protocols and adaptive team-based strategies to optimize resuscitation outcomes across diverse rescuer populations. Conclusion This study demonstrates a significant decline in chest compression quality within the first two minutes of CPR, particularly among female and lighter-weight healthcare providers. Female participants exhibited a marked reduction in both the number and depth of effective compressions after the first minute, especially during the third and fourth 30-second intervals. Additionally, women weighing less than 60 kg delivered significantly fewer compressions meeting the recommended depth compared to heavier participants. Although male participants, especially those weighing ≥ 60 kg, maintained the recommended compression rate, the total number of adequately deep compressions still fell below guideline standards. This underscores the importance of concurrently assessing both compression rate and depth when evaluating chest compression quality. While fatigue was not directly measured, the observed performance decline after the first minute may reflect reduced physical capacity in certain subgroups. Accordingly, the universal application of the current two-minute rescuer rotation guideline may not be optimal for all individuals. Shorter rotation intervals (e.g., every 30–60 seconds) could help preserve effective compression quality but should be balanced against the potential increase in hands-off time. Overall, adopting a tailored, competency-based approach to CPR training and team organization—considering individual physical characteristics and demonstrated compression performance—may enhance chest compression effectiveness, improve guideline adherence, and ultimately lead to better patient outcomes. Declarations Ethics approval and consent to participate This study was approved by the Ethics Committee of Shahrekord University of Medical Sciences (Approval code: [IR.SKUMS.REC.1402.093]). Written informed consent was obtained from all participants prior to data collection. All procedures performed were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments. Consent for publication Not applicable. Availability of data and materials The datasets generated and/or analyzed during the current study are not publicly available due to institutional restrictions but are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding This research was supported by Shahrekord University of Medical Sciences [Grant number: 6936]. The funding body had no role in the design of the study, data collection, analysis, interpretation, or manuscript writing. Authors’ contributions Raziyeh Tajik conceived and designed the study. Raziyeh Tajik, Mohammad Heydari, Hadi Raisei Shahraki, Rahim Ali Sheikhi collected and analyzed the data. Rahim Ali Sheikhi drafted the manuscript. All authors reviewed and approved the final manuscript. Acknowledgements This study was conducted as part of a Master of Science (MSc) thesis in Nursing, approved by Shahrekord University of Medical Sciences. We would like to express our sincere appreciation to the esteemed officials at the Vice-Chancellor for Research and Technology and the Office of Postgraduate Education of Shahrekord University of Medical Sciences for their valuable support. We are also deeply grateful for the kind cooperation of the hospital managers and the respected patients. Without their support and participation, this research would not have been possible. References Berdowski J, Berg RA, Tijssen JG, Koster RW. Global incidences of out-of-hospital cardiac arrest and survival rates: Systematic review of 67 prospective studies. Resuscitation. 2010;81(11):1479–87. Razzak JA, Kellermann AL. Emergency medical care in developing countries: is it worthwhile? Bull World Health Organ. 2002;80(11):900–5. Meaney PA, Bobrow BJ, Mancini ME, Christenson J, de Caen AR, Bhanji F, et al. Cardiopulmonary resuscitation quality: improving cardiac resuscitation outcomes both inside and outside the hospital. 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Nurses' performance and self efficacy in CPR: A cross sectional study in southeast Iran. Iran J Nurs Midwifery Res. 2019;24(5):345–50. Nishiyama C, Iwami T, Murakami Y, et al. Effectiveness of simplified 30 second chest compression training for laypersons: a randomized controlled study. Resuscitation. 2014;85(9):1163–8. Russo SG, Neumann P, Reinhardt S, et al. Impact of physical fitness and body mass index on the performance of external chest compressions. J Emerg Med. 2011;41(2):183–8. Baubin MA, Schneider T, Mair M, et al. Frequency of inadequate chest compression depth and rate in out of hospital cardiac arrest. Resuscitation. 2007;73(3):462–9. Yang CW, Yen ZS, McGowan JE, et al. A systematic review of quality of CPR in simulation studies: Are we up to standard? Resuscitation. 2012;83(7):869–75. Kılıç TY, Kılıç K, Uğur M, Uysal E, Güneysel Ö. Comparison of 1 minute versus 2 minute compression cycles on rescuer fatigue and CPR quality in laypersons: A randomized crossover study. Am J Emerg Med. 2021;43:18–23. Khoury A, Sall FS, De Luca A, et al. Influence of stress, fatigue, and gender on CPR quality during simulated cardiac arrest. Resuscitation. 2020;146:28–34. Cheng A, Brown LL, Duff JP, et al. Improving cardiopulmonary resuscitation training in pediatrics: A systematic review. Pediatrics. 2018;141(1):e20172852. Sutton RM, Niles D, Meaney PA, et al. Low-dose, high-frequency CPR training improves skill retention in healthcare providers. Resuscitation. 2011;82(7):795–800. Abella BS, Alvarado JP, Myklebust H, et al. Quality of cardiopulmonary resuscitation during in-hospital cardiac arrest. JAMA. 2005;293(3):305–10. Additional Declarations No competing interests reported. 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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-7134265","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":504894437,"identity":"801c5075-4b3c-4322-b9d8-5c1ac2fbef97","order_by":0,"name":"Raziyeh Tajik","email":"","orcid":"","institution":"Shahrekord University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Raziyeh","middleName":"","lastName":"Tajik","suffix":""},{"id":504894438,"identity":"17fa81cd-8101-4985-89a2-45d99c43be2d","order_by":1,"name":"Rahim Ali Sheikhi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABFklEQVRIiWNgGAWjYBAC+wYehgNAOoGBgY2NIaGCTQ4keuABHi0GB1C0nOEzBmtJIKCFAa6FsU0usQHKxa3l+NmDh24w1OXxz0hLe/CwzSx9ftjhh0Bb7OR0G3D4pScv4XAOw+FiiRtpxw0SzqXlbrydZgDUkmxsdgC7FjuGHAOglgOJDTfS2yQSyo7lbpydANJyIHEbDi3G/G9AWuoS54O1sP1PN5yd/gGvFsMZYFuYEzfcSDsmkdDGliAvnYPfFoMbIFsMDiduPPMsTSLhDJvhBumcggMJBrj9YnA+x/hzTkVd4rzjaWaSPyrY5OVnp2/+8KHCTg6XFqhGIBZIgLIPwEQIAn6oofINxKgeBaNgFIyCkQQAiNxsQO9HwFcAAAAASUVORK5CYII=","orcid":"","institution":"Shahrekord University of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"Rahim","middleName":"Ali","lastName":"Sheikhi","suffix":""},{"id":504894439,"identity":"60a79498-7de3-4734-af3a-5db861ece731","order_by":2,"name":"Mohammad Heydari","email":"","orcid":"","institution":"Shahrekord University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"","lastName":"Heydari","suffix":""},{"id":504894440,"identity":"4ab57bee-3f00-4007-bb94-8ca780b9738b","order_by":3,"name":"Hadi Raeisi Shahraki","email":"","orcid":"","institution":"Shahrekord University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Hadi","middleName":"Raeisi","lastName":"Shahraki","suffix":""}],"badges":[],"createdAt":"2025-07-15 22:53:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7134265/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7134265/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90330000,"identity":"bd0c2a6b-b77b-40cb-907d-f28b1d8aa6bc","added_by":"auto","created_at":"2025-09-01 13:00:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":865956,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7134265/v1/25131e1c-3f47-45f6-bddb-577e20b630fe.pdf"},{"id":90329317,"identity":"80840536-1c45-42a6-8028-0b0734395467","added_by":"auto","created_at":"2025-09-01 12:52:13","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":13302,"visible":true,"origin":"","legend":"","description":"","filename":"Suplmentarytable12.docx","url":"https://assets-eu.researchsquare.com/files/rs-7134265/v1/0e9b5711c0b379dda22f7e49.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Temporal and Weight-Related Variations in Chest Compression Quality during CPR: A 30-Second Interval Manikin Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSudden cardiac arrest (SCA) is a leading cause of death globally and constitutes one of the most time-sensitive medical emergencies. The abrupt cessation of effective cardiac activity results in immediate disruption of blood flow to vital organs such as the brain and heart, causing irreversible damage or death if not promptly treated [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Globally, approximately 3.17\u0026nbsp;million people die annually due to cardiac arrest, with projections expected to exceed 3.26\u0026nbsp;million by 2030 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In Iran, SCA also poses a substantial burden on the healthcare system [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eHigh-quality chest compressions are the cornerstone of effective cardiopulmonary resuscitation (CPR) and critically influence patient survival. According to the American Heart Association (AHA) and the International Liaison Committee on Resuscitation (ILCOR) guidelines, optimal chest compressions should reach a depth of 5–6 cm, be delivered at a rate of 100–120 compressions per minute, and involve minimal interruptions [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The 2015 AHA update, which revised the resuscitation sequence from ABC to CAB, emphasized the importance of promptly initiating and maintaining effective chest compressions [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eHowever, maintaining high-quality chest compressions over time is challenging, particularly due to rescuer fatigue. Prior studies demonstrate a significant decline in compression depth within the first minute of continuous chest compressions, compromising hemodynamic efficacy [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e–\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Although current guidelines recommend rotating rescuers approximately every two minutes to reduce fatigue-related deterioration, this practice is inconsistently applied in clinical settings [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn addition to fatigue, rescuer physical characteristics—particularly body weight—may affect chest compression quality. Some evidence suggests that individuals with higher body mass may generate more forceful and sustained compressions [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Nevertheless, few studies have examined the combined effects of time and rescuer physical attributes on compression quality, especially using short, fine-grained temporal intervals within CPR cycles.\u003c/p\u003e\u003cp\u003eConsidering that body weight distributions vary across populations, and recognizing that simplified cutoff values may not capture all nuances, this study employed a 60 kg threshold—near the sample median and consistent with prior literature indicating mechanical limitations below this weight—for descriptive subgroup analyses. We acknowledge this binary classification’s limitations and emphasize interpretation within the relevant population context.\u003c/p\u003e\u003cp\u003eIn the Iranian healthcare setting, prior research has highlighted concerns regarding chest compression quality and practical skills among healthcare providers [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Nurses and emergency medical technicians (EMTs), often the first responders in resuscitation, have a vital role in patient outcomes.\u003c/p\u003e\u003cp\u003eThis study aimed to analyze time-dependent changes in chest compression quality during a 2-minute continuous compression cycle, using 30-second intervals to provide higher temporal resolution. Additionally, it explored the association between rescuer body weight and compression quality. Understanding the timing and extent of performance decline, as well as physical factors influencing chest compression efficacy, can inform tailored training and potentially optimize rotation strategies. However, rotation frequency must balance the benefits of reducing rescuer fatigue with the risks of increased hands-off time, underscoring the need for evidence-based approaches to maintain continuous high-quality compressions.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cb\u003eStudy Design and Setting\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThis cross-sectional, simulation-based analytical study was conducted in 2023 at Shahrekord University of Medical Sciences (SKUMS), Iran. The primary objective was to assess the quality of chest compressions during the first 2 minutes of cardiopulmonary resuscitation (CPR), focusing specifically on the influence of rescuer sex and body weight. Data collection took place in clinical skills laboratories of Hajar and Kashani Hospitals and affiliated emergency medical services (EMS) training centers.\u003c/p\u003e\u003cp\u003e\u003cb\u003eParticipants and Sampling\u003c/b\u003e\u003c/p\u003e\u003cp\u003eEligible participants included nurses and EMS technicians affiliated with SKUMS. Inclusion criteria were: (1) holding a BSc or MSc in nursing, or a diploma/degree in EMS or operating room technology; (2) at least 6 months of clinical experience; and (3) provision of written informed consent. Individuals with known musculoskeletal or cardiovascular disorders or incomplete data were excluded. Convenience sampling was used.\u003c/p\u003e\u003cp\u003eA pilot study involving 15 participants estimated a mean of 180 ± 30 effective chest compressions per 2-minute cycle, which informed the sample size calculation.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSample Size Calculation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTo detect a difference of ≥ 15 effective compressions from the American Heart Association (AHA) benchmark of 200 compressions, with 80% power and α = 0.05 (two-tailed), a sample size of 98 was calculated using G*Power 3.1. To accommodate potential dropouts, 103 participants were recruited.\u003c/p\u003e\u003cp\u003e\u003cb\u003eBody Weight Classification\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBody weight was measured using a calibrated digital scale prior to testing. For inferential analyses, weight was treated as a continuous variable to preserve statistical power and avoid arbitrary categorization. However, for descriptive and interpretive purposes, participants were divided into two groups using a cutoff of 60 kg. This cutoff was chosen based on the approximate median weight of the sample and prior literature suggesting mechanical limitations in chest compression performance below this threshold. It is acknowledged that this binary classification is a simplified approach and may not fully capture the spectrum of weight-related effects, especially in populations where average body weight varies substantially.\u003c/p\u003e\u003cp\u003e\u003cb\u003eData Collection and Procedure\u003c/b\u003e\u003c/p\u003e\u003cp\u003eParticipants performed three consecutive 2-minute cycles of continuous chest compressions on a Resusci Anne manikin (Laerdal, Norway) placed on a firm surface. A 4-minute rest interval separated each cycle, simulating standard three-person CPR team rotations as recommended by the AHA. This rest interval was intended to minimize fatigue accumulation across cycles. All sessions were video recorded for quality control.\u003c/p\u003e\u003cp\u003eAlthough three cycles were recorded, preliminary mixed-effects analyses showed no statistically significant differences in compression depth or rate across cycles (p \u0026gt; 0.10). Therefore, only data from the first cycle were used for primary analyses. Summary results for cycles 2 and 3 are available in Supplementary Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003eand S2.\u003c/p\u003e\u003cp\u003eTo reduce performance bias and simulate real-world conditions, the manikin’s visual feedback system (LED indicators for compression depth) was disabled during testing. Chest compression data were extracted for each 30-second interval (epochs): 0–30, 30–60, 60–90, and 90–120 seconds.\u003c/p\u003e\u003cp\u003e\u003cb\u003eOutcomes\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003ePrimary outcome\u003c/b\u003e: Number of effective chest compressions during the first 2-minute cycle. Effective compressions were defined as compressions achieving a depth of 5–6 cm based on Laerdal manikin criteria aligned with AHA guidelines.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eSecondary outcomes\u003c/b\u003e: (1) total number of compressions delivered; (2) number of effective compressions within each 30-second interval.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eTraining and Standardization\u003c/b\u003e\u003c/p\u003e\u003cp\u003e Before testing, participants underwent a brief refresher training session based on the 2020 AHA Basic Life Support guidelines. They practiced on the same manikin with real-time feedback enabled to standardize skill level. However, during the experimental trials, visual feedback was disabled to mimic actual clinical scenarios and minimize bias.\u003c/p\u003e\u003cp\u003eThe interval between refresher training and participation was kept under one week to reduce skill decay.\u003c/p\u003e\u003cp\u003e\u003cb\u003eValidity and Reliability\u003c/b\u003e\u003c/p\u003e\u003cp\u003eData collection tools and procedures were reviewed and approved by a five-member expert panel in emergency medicine and resuscitation science. Video-based scoring of compressions demonstrated excellent inter-rater reliability, with a Cohen’s kappa coefficient of 0.88.\u003c/p\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eAll analyses were conducted using SPSS version 23.0 (IBM Corp., Armonk, NY, USA) and R software. Descriptive statistics summarized participant characteristics and chest compression performance.\u003c/p\u003e\u003cp\u003eA linear mixed-effects regression model examined the association between body weight (continuous) and effective chest compressions across the four 30-second intervals of the first CPR cycle. The model included random intercepts to account for repeated measures within participants and tested interaction terms between body weight and sex to explore effect modification.\u003c/p\u003e\u003cp\u003e “Effective compression” was explicitly defined as a compression depth between 5 and 6 cm per Laerdal manikin standards and AHA guidelines. Although data on compression rate, hand position, and chest recoil were collected, the primary focus remained on compression depth and total effective compressions.\u003c/p\u003e\u003cp\u003eAll model assumptions were checked and met. Statistical significance was set at p \u0026lt; 0.05 (two-tailed).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eParticipant Characteristics\u003c/b\u003e\u003c/p\u003e\u003cp\u003eA total of 103 healthcare professionals affiliated with Shahrekord University of Medical Sciences participated in the study. Among them, 54 (52.4%) were female and 49 (47.6%) were male. Most participants were employed in hospital settings (n\u0026thinsp;=\u0026thinsp;83, 80.6%), while 20 (19.4%) worked in prehospital emergency medical services (EMS). Regarding professional roles, 93 (90.3%) were nurses and 10 (9.7%) were EMTs. \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe mean age was 25.32\u0026thinsp;\u0026plusmn;\u0026thinsp;2.86 years, and the mean work experience was 4.52\u0026thinsp;\u0026plusmn;\u0026thinsp;3.27 years (range: 0.7\u0026ndash;16 years). Participants' weight ranged from 44 to 106 kg, with a mean of 69.83\u0026thinsp;\u0026plusmn;\u0026thinsp;14.68 kg.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eParticipant Demographics and Characteristics\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCategory / Range\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMale / Female\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e49 (47.6%) / 54 (52.4%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWorkplace\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHospital / EMS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e83 (80.6%) / 20 (19.4%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProfession\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNurse / EMT\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e93 (90.3%) / 10 (9.7%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e24\u0026ndash;44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e25.32\u0026thinsp;\u0026plusmn;\u0026thinsp;2.86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWork experience (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.7\u0026ndash;16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4.52\u0026thinsp;\u0026plusmn;\u0026thinsp;3.27\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeight (kg)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e44\u0026ndash;106\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e69.83\u0026thinsp;\u0026plusmn;\u0026thinsp;14.68\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eChest Compression Performance across Cycles\u003c/b\u003e\u003c/p\u003e\u003cp\u003eParticipants performed three consecutive 2-minute cycles of chest compressions. Analysis using linear mixed-effects models indicated no statistically significant differences in compression depth or rate across the three cycles (p\u0026thinsp;\u0026gt;\u0026thinsp;0.10), suggesting consistent performance. Therefore, only data from the first cycle were used in the primary analyses to reduce redundancy. Supplementary Tables S1 and S2 provide summary results for cycles 2 and 3.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTime-Dependent Decline in Compression Quality\u003c/b\u003e\u003c/p\u003e\u003cp\u003eChest compression performance was further analyzed across four consecutive 30-second intervals within the first cycle using a linear mixed-effects regression model.\u003cb\u003e)\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eFemale participants showed a significant decline in the number of effective compressions over time (mean difference from first to last interval: \u0026minus;\u0026thinsp;7.09, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMale participants maintained relatively stable effective compression counts over the intervals (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.342\u003cb\u003e). (\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eCompression rate declined in both sexes over time, with a more pronounced reduction among females.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eA significant interaction between time interval and sex was observed (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01), indicating a more rapid decline in performance among females.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eEffective Compressions by Time Interval and Sex\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInterval (sec)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFemale (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMale (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e0\u0026ndash;30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e13.57\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e36.40\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e30\u0026ndash;60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e12.16\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e37.63\u0026thinsp;\u0026plusmn;\u0026thinsp;9.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e60\u0026ndash;90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e9.92\u0026thinsp;\u0026plusmn;\u0026thinsp;6.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e36.01\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e90\u0026ndash;120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e6.48\u0026thinsp;\u0026plusmn;\u0026thinsp;5.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e34.79\u0026thinsp;\u0026plusmn;\u0026thinsp;9.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCompression Rate by Time Interval and Sex (compressions/min)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInterval (sec)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFemale (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMale (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e0\u0026ndash;30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e40.69\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e48.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e30\u0026ndash;60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e38.89\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e46.32\u0026thinsp;\u0026plusmn;\u0026thinsp;5.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e60\u0026ndash;90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e38.25\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e45.79\u0026thinsp;\u0026plusmn;\u0026thinsp;5.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e90\u0026ndash;120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e35.58\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e42.47\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eAssociation between Body Weight and Compression Quality\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBody weight was analyzed as both a continuous variable and using a 60 kg cutoff. It is noted that the 60 kg threshold may not universally define low weight, and future studies should consider more granular stratification.(Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e )\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eParticipants weighing\u0026thinsp;\u0026ge;\u0026thinsp;60 kg performed more total compressions, though this difference was not statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.126).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe number of effective compressions was significantly higher in participants\u0026thinsp;\u0026ge;\u0026thinsp;60 kg compared to those\u0026thinsp;\u0026lt;\u0026thinsp;60 kg (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTotal and Effective Compressions by Weight Group\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeight Group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMean Total Compressions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e176.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e32.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e189.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e40.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e0.126\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c8\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWeight Group\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e\u003cb\u003eMean Effective Compressions\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e\u003cb\u003eSD\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u003c/b\u003e\u003cb\u003e-value\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e27.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e46.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e114.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e69.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eComparison with AHA Benchmark\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe American Heart Association (AHA) recommends approximately 200 effective compressions per 2-minute cycle. One-sample \u003cem\u003et\u003c/em\u003e-tests were used to compare observed effective compression counts against this benchmark, stratified by sex and weight.( Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eNone of the subgroups met the AHA benchmark.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe lowest performance was observed among females weighing\u0026thinsp;\u0026lt;\u0026thinsp;60 kg.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eDue to a very small sample size (n\u0026thinsp;=\u0026thinsp;2), data for males weighing\u0026thinsp;\u0026lt;\u0026thinsp;60 kg should be interpreted cautiously.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of Effective Compressions with AHA Benchmark (200 Compressions per Cycle)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWeight Group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003en\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMean Effective Compressions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eMeets AHA?\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e22.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026ndash;23.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e❌ No\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e78.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e55.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026ndash;11.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e❌ No\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e97.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e90.51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026ndash;1.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.230\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e⚠ฏ Insufficient data\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;60 kg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e149.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e53.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026ndash;6.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e❌ No\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eSummary of Key Findings\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eChest compression quality (in terms of depth and rate) declined significantly during the 2-minute cycle, especially among female participants.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eHigher body weight was associated with better chest compression quality, with a stronger effect noted in female participants.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eNone of the sex or weight subgroups achieved the AHA-recommended 200 effective compressions per cycle.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThese findings highlight the need for optimized rescuer rotation strategies that balance fatigue mitigation and minimize interruptions.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study evaluated the quality of chest compressions over a two-minute cycle using a novel approach analyzing discrete 30-second intervals. This fine-grained temporal analysis is a key strength, providing new insights into the dynamics of rescuer performance over time\u0026mdash;a perspective rarely addressed in prior research (11).\u003c/p\u003e\u003cp\u003eOur results demonstrated a significant decline in both the number and depth of effective chest compressions among female participants, particularly during the latter half of the cycle. In contrast, male participants maintained relatively stable compression performance throughout the two minutes. Notably, participants weighing less than 60 kg\u0026mdash;predominantly females\u0026mdash;delivered significantly fewer compressions meeting the guideline-recommended depth (\u0026ge;\u0026thinsp;5 cm). However, it should be noted that the 60 kg threshold may not represent a low body weight in all populations, especially among females. A more detailed analysis of weight distribution within the \u0026lt;\u0026thinsp;60 kg group could clarify whether the observed effect is driven by very low weights or is consistent across the entire subgroup.\u003c/p\u003e\u003cp\u003eAlthough objective fatigue measurement tools were not employed, the marked reduction in compression quality after the first minute\u0026mdash;especially among females and lighter individuals\u0026mdash;may indicate declining physical capacity. Prior studies using physiological and self-reported fatigue indices have reported similar patterns, with women showing earlier performance deterioration during continuous compressions (14\u0026ndash;16).\u003c/p\u003e\u003cp\u003eThe 30-second interval analysis further revealed that the third and fourth intervals (after 60 seconds) are critical turning points for compression quality decline. This suggests that the conventional 2-minute rescuer rotation interval may be too long for certain subgroups, particularly women and lighter-weight individuals. However, shortening rotation intervals alone could increase hands-off time and reduce the chest compression fraction (CCF), a critical factor for successful resuscitation. Therefore, alongside shorter rotation cycles, other strategies such as incorporating a dedicated CPR coach\u0026mdash;as recommended by recent AHA guidelines\u0026mdash;should be considered to maintain compression quality and minimize interruptions (17,18).\u003c/p\u003e\u003cp\u003eAnother important observation was the discrepancy between compression rate and depth. While male participants, especially those\u0026thinsp;\u0026ge;\u0026thinsp;60 kg, met or exceeded the recommended rate of \u0026ge;\u0026thinsp;100 compressions per minute, the number of compressions achieving adequate depth remained below the target of 200 compressions per two-minute cycle. This indicates that meeting compression rate alone does not guarantee high-quality chest compressions.\u003c/p\u003e\u003cp\u003eThus, simultaneous monitoring and emphasis on both compression rate and depth during training and evaluation are essential. Sole reliance on total compression count may overestimate CPR effectiveness if compressions are too shallow to generate sufficient perfusion.\u003c/p\u003e\u003cp\u003eFinally, as this study was conducted in a controlled simulation environment, female rescuers may experience even greater physical exhaustion during real emergencies where environmental stressors, emotional factors, and operational challenges further impair performance. These results highlight the need for gender- and weight-sensitive training protocols and adaptive team-based strategies to optimize resuscitation outcomes across diverse rescuer populations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrates a significant decline in chest compression quality within the first two minutes of CPR, particularly among female and lighter-weight healthcare providers. Female participants exhibited a marked reduction in both the number and depth of effective compressions after the first minute, especially during the third and fourth 30-second intervals. Additionally, women weighing less than 60 kg delivered significantly fewer compressions meeting the recommended depth compared to heavier participants.\u003c/p\u003e\u003cp\u003e Although male participants, especially those weighing\u0026thinsp;\u0026ge;\u0026thinsp;60 kg, maintained the recommended compression rate, the total number of adequately deep compressions still fell below guideline standards. This underscores the importance of concurrently assessing both compression rate and depth when evaluating chest compression quality.\u003c/p\u003e\u003cp\u003eWhile fatigue was not directly measured, the observed performance decline after the first minute may reflect reduced physical capacity in certain subgroups. Accordingly, the universal application of the current two-minute rescuer rotation guideline may not be optimal for all individuals. Shorter rotation intervals (e.g., every 30\u0026ndash;60 seconds) could help preserve effective compression quality but should be balanced against the potential increase in hands-off time.\u003c/p\u003e\u003cp\u003e Overall, adopting a tailored, competency-based approach to CPR training and team organization\u0026mdash;considering individual physical characteristics and demonstrated compression performance\u0026mdash;may enhance chest compression effectiveness, improve guideline adherence, and ultimately lead to better patient outcomes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of Shahrekord University of Medical Sciences (Approval code: [IR.SKUMS.REC.1402.093]). Written informed consent was obtained from all participants prior to data collection. All procedures performed were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are not publicly available due to institutional restrictions but are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by Shahrekord University of Medical Sciences [Grant number: 6936]. The funding body had no role in the design of the study, data collection, analysis, interpretation, or manuscript writing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRaziyeh Tajik conceived and designed the study. Raziyeh Tajik, Mohammad Heydari, Hadi Raisei Shahraki, Rahim Ali Sheikhi collected and analyzed the data. \u0026nbsp;Rahim Ali Sheikhi drafted the manuscript. All authors reviewed and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted as part of a Master of Science (MSc) thesis in Nursing, approved by Shahrekord University of Medical Sciences. We would like to express our sincere appreciation to the esteemed officials at the Vice-Chancellor for Research and Technology and the Office of Postgraduate Education of Shahrekord University of Medical Sciences for their valuable support. We are also deeply grateful for the kind cooperation of the hospital managers and the respected patients. Without their support and participation, this research would not have been possible.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBerdowski J, Berg RA, Tijssen JG, Koster RW. Global incidences of out-of-hospital cardiac arrest and survival rates: Systematic review of 67 prospective studies. Resuscitation. 2010;81(11):1479\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRazzak JA, Kellermann AL. Emergency medical care in developing countries: is it worthwhile? Bull World Health Organ. 2002;80(11):900\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMeaney PA, Bobrow BJ, Mancini ME, Christenson J, de Caen AR, Bhanji F, et al. Cardiopulmonary resuscitation quality: improving cardiac resuscitation outcomes both inside and outside the hospital. Circulation. 2013;128(4):417\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePanchal AR, Bartos JA, Caba\u0026ntilde;as JG, Donnino MW, Drennan IR, Hirsch KG, et al. 2020 American Heart Association Guidelines for CPR and Emergency Cardiovascular Care. Circulation. 2020;142(16suppl2):S366\u0026ndash;468.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHightower D, Thomas SH, Stone CK, Dunn K, March JA. Decay in quality of closed chest compressions over time. Ann Emerg Med. 1995;26(3):300\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOchoa FJ, Ramalle G\u0026oacute;mara E, Lisa V, Saralegui I. The effect of rescuer fatigue on the quality of chest compressions. Resuscitation. 1998;37(3):149\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAshton A, McCluskey A, Gwinnutt CL, Keenan AM. Effect of rescuer fatigue on performance of continuous external chest compressions over 3 min. Resuscitation. 2002;55(2):151\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShin J, Rhee JE, Kim K, Kim TY, Kim YJ, Jo YH, et al. The effect of rescuer gender and rotation interval on chest compression quality during simulated cardiopulmonary resuscitation. Resuscitation. 2014;85(12):1789\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAftabi M, Koohestani HR, Dehghan Nayeri N, Khankeh H. Nurses' performance and self efficacy in CPR: A cross sectional study in southeast Iran. Iran J Nurs Midwifery Res. 2019;24(5):345\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNishiyama C, Iwami T, Murakami Y, et al. Effectiveness of simplified 30 second chest compression training for laypersons: a randomized controlled study. Resuscitation. 2014;85(9):1163\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRusso SG, Neumann P, Reinhardt S, et al. Impact of physical fitness and body mass index on the performance of external chest compressions. J Emerg Med. 2011;41(2):183\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaubin MA, Schneider T, Mair M, et al. Frequency of inadequate chest compression depth and rate in out of hospital cardiac arrest. Resuscitation. 2007;73(3):462\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYang CW, Yen ZS, McGowan JE, et al. A systematic review of quality of CPR in simulation studies: Are we up to standard? Resuscitation. 2012;83(7):869\u0026ndash;75.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKılı\u0026ccedil; TY, Kılı\u0026ccedil; K, Uğur M, Uysal E, G\u0026uuml;neysel \u0026Ouml;. Comparison of 1 minute versus 2 minute compression cycles on rescuer fatigue and CPR quality in laypersons: A randomized crossover study. Am J Emerg Med. 2021;43:18\u0026ndash;23.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhoury A, Sall FS, De Luca A, et al. Influence of stress, fatigue, and gender on CPR quality during simulated cardiac arrest. Resuscitation. 2020;146:28\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCheng A, Brown LL, Duff JP, et al. Improving cardiopulmonary resuscitation training in pediatrics: A systematic review. Pediatrics. 2018;141(1):e20172852.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSutton RM, Niles D, Meaney PA, et al. Low-dose, high-frequency CPR training improves skill retention in healthcare providers. Resuscitation. 2011;82(7):795\u0026ndash;800.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAbella BS, Alvarado JP, Myklebust H, et al. Quality of cardiopulmonary resuscitation during in-hospital cardiac arrest. JAMA. 2005;293(3):305\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-medical-education","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"meed","sideBox":"Learn more about [BMC Medical Education](http://bmcmededuc.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/meed/default.aspx","title":"BMC Medical Education","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Cardiopulmonary resuscitation, chest compression, gender differences, body weight, healthcare workers, CPR quality, simulation","lastPublishedDoi":"10.21203/rs.3.rs-7134265/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7134265/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHigh-quality chest compressions are essential for effective cardiopulmonary resuscitation (CPR). This study aimed to evaluate the influence of rescuer sex and body weight on chest compression quality during the first two minutes, with emphasis on temporal changes within 30-second intervals.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this cross-sectional simulation study, 103 healthcare providers performed three 2-minute cycles of continuous chest compressions on a manikin. Data from all cycles were analyzed; however, only first-cycle results are reported due to performance consistency across cycles. Compression quality was assessed in 30-second intervals, and weight was analyzed both continuously and using a 60-kg cutoff. The ILCOR benchmark of 200–240 compressions per 2 minutes was used for comparison.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFemale participants demonstrated a significant decline in the number of effective compressions (5–6 cm depth) after the first minute (p \u0026lt; 0.001), particularly in the last two intervals, whereas male participants maintained relatively stable performance (p = 0.342). Participants weighing ≥60 kg delivered significantly more effective compressions than those \u0026lt;60 kg (mean: 114.16 vs. 27.34 compressions; p \u0026lt; 0.001). Although total compression counts were higher in heavier participants, this difference was not statistically significant (p = 0.126). Notably, the mean number of effective compressions in all subgroups remained below the ILCOR-recommended range.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRescuer sex and body weight significantly influence chest compression quality, especially depth, with females and lighter-weight individuals showing a marked decline after one minute. These findings highlight the need for careful consideration of rotation intervals and suggest that individualized CPR training strategies—accounting for physical characteristics—may improve adherence to guidelines. However, potential trade-offs, such as increased hands-off time from more frequent rescuer changes, should be carefully weighed in clinical practice.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration:\u003c/strong\u003e Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial sponsor: \u003c/strong\u003eShahrekord University of Medical Science\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This research is financially supported by Shahrekord University of Medical\u003cstrong\u003e \u003c/strong\u003eSciences.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy status: \u003c/strong\u003eThis study has been completed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRelated article: \u003c/strong\u003eNo related articles for this study have been submitted to any journal. The study's sponsor and funders had no involvement in the data's design, analysis, or interpretation. The content is entirely the authors' responsibility and does not necessarily reflect the official views of the National Institutes of Health.\u003c/p\u003e","manuscriptTitle":"Temporal and Weight-Related Variations in Chest Compression Quality during CPR: A 30-Second Interval Manikin Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-01 12:44:09","doi":"10.21203/rs.3.rs-7134265/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2025-08-22T11:29:15+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-07-29T11:49:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-28T11:04:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-28T11:03:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Medical Education","date":"2025-07-15T22:41:10+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-medical-education","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"meed","sideBox":"Learn more about [BMC Medical Education](http://bmcmededuc.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/meed/default.aspx","title":"BMC Medical Education","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"de0b64ac-152f-41b2-8bad-8f09c9bd0630","owner":[],"postedDate":"September 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-09-01T12:44:09+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-01 12:44:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7134265","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7134265","identity":"rs-7134265","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}