Archives of Academic Emergency Medicine. 2021; 9(1): e4 https://doi.org/10.22037/aaem.v9i1.994 OR I G I N A L RE S E A RC H Straddle versus Conventional Chest Compressions in a Confined Space; a Comparative Study Praphaphorn Supatanakij1, Chaiyaporn Yuksen1∗, Terapat Chantawong1, Pilaiwan Sawangwong1, Chetsadakon Jenpanitpong1, Jirayoot Patchkrua1, Ponlawat Kanchayawong1 1. Department of Emergency Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. Received: September 2020; Accepted: October 2020; Published online: 14 November 2020 Abstract: Introduction: When cardiac arrest occurs in a confined space, such as in an aircraft or ambulance, kneeling by the patient’s side may be difficult. Straddle chest compression is an alternative technique that can be used in a confined space. This study was performed to compare the quality of chest compressions in straddle versus conventional CPR on a manikin model. Methods: The participants were randomized into two groups using the sequential numbered, opaque, sealed envelope method chosen through block-of-four randomization: strad- dle and conventional chest compression technique. Each participant performed a maximum of 4 minutes of hands-only chest compressions, and quality parameters (compression rate and depth) were recorded from the defibrillator’s monitor. Results: 124 participants with mean age of 26.67 ± 6.90 years (27.58% male) were studied. There was no difference in the mean compression rate between the conventional and straddle chest compres- sion techniques (126.18 ± 17.11 and 127.01 ± 21.01 compressions/min, respectively; p = 0.811) or their mean compression depth (43.8 ± 9.60 and 43.4 ± 9.10 mm, respectively; p = 0.830). The participants’ comfort and fa- tigue were assessed through changes in their vital signs. In both methods, statistically significant differences were observed in vital signs before and after performing chest compression, but the differences were not clin- ically significant. In addition, there was no difference between the 2 groups in this regard. Conclusion: The quality of CPR using the straddle chest compression was as good as conventional chest compression technique. No significant differences were found in the quality of chest compressions or the participants’ comfort and fa- tigue levels. Keywords: cardiopulmonary resuscitation; heart arrest; heart massage; emergency medical service; ambulances Cite this article as: Supatanakij P, Yuksen C, Chantawong T, Sawangwong P, Jenpanitpong C, Patchkrua J, Kanchayawong P. Straddle versus Conventional Chest Compressions in a Confined Space; a Comparative Study. Arch Acad Emerg Med. 2021; 9(1): e4. 1. Introduction Sudden cardiac arrest can occur in either an emergency room or outside a hospital, which is one of the leading causes of death in many countries worldwide (1). The survival rate af- ter receiving life support inside and outside hospitals ranges from 2% to 10% and from 7.4% to 27%, respectively (2-5). Ba- sic life support (BLS) after sudden cardiac arrest can increase the survival rate (6). Chest compression is an important step in basic life sup- port, which is considered a standard procedure for health- care providers and lay-rescuers at the scene of sudden car- ∗Corresponding Author: Chaiyaporn Yuksen; Department of Emergency Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University Bangkok, Thailand. Email: Chaipool0634@hotmail.com, Tel: 66894726911, ORCID:0000-0002-4890-7176 diac arrest. Chest compression is more effective when the patient is lying in supine position on a relatively hard sur- face such as ground or floor (7, 8). The compression depth should be at least 2 inches or 5 centimeters, but not exceed 2.5 inches or 6 centimeters for adult cardiac arrest patients (9, 10). The chest should be released and allowed to recoil completely before the initiation of another compression (11, 12). The compression rate should be at least 100-120 com- pressions per minute. It is important to ensure that no inter- ruptions occur while performing chest compression (13, 14). Those performing cardiac massage for patients with sud- den cardiac arrest should not stop chest compression unless the patient should be evacuated from the scene or electri- cal defibrillation should be performed, otherwise its effec- tiveness will decrease. (15). In out-of-hospital cardiac arrest (OHCA), some patients should be immediately transported to a hospital to receive definite treatments such as extracor- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem P. Supatanakij et al. 2 poreal cardiopulmonary resuscitation in refractory shock- able cardiac arrest, thus, chest compressions must be contin- ued during transport. However, performing chest compres- sion when positioned beside the patient on a moving vehicle will alter the quality of chest compression and cause injury to providers. Another situation is in an aircraft where it may be difficult for providers to kneel down and perform chest com- pression when positioned lateral to the patient due to con- fined space. Alternative techniques are available to perform chest com- pression in confined space areas such as ambulances or air- crafts (16). Chest compression when the provider is posi- tioned over the patient’s head (over-the-head CPR) or strad- dled over the patient’s legs (straddle CPR) may be useful in situations where space is limited (17, 18). As mentioned above, straddle CPR may be useful to perform chest compression during transportation of the patient on an ambulance with high speed and limited spaced, because straddling over the patient’s legs is stronger and safer than standing beside the stretcher. However, the quality of chest compression in straddle technique has not been studied in detail. The objectives of this study were to 1) compare the quality of conventional and straddle chest compressions us- ing a manikin model and 2) study the comfort and fatigue of providers by measuring the changes in their vital signs be- fore and after performing the two different chest compres- sion techniques. 2. Methods 2.1. Study design and setting This was a cross-sectional comparative study with strati- fied randomization of participants. The study was con- ducted from December 2016 to January 2017 at the Faculty of Medicine Ramathibodi Hospital, a university-affiliated su- per tertiary care hospital in Bangkok, Thailand. Partici- pants consisted of individuals in both healthcare (emergency physicians, general practitioners, nurses, ambulance staffs, medical and paramedic students) and non-healthcare (air- line staff, flight attendants, and cabin crew members) pro- fessions, were enrolled to the study then provided writ- ten informed consent. The participants were stratified into two groups according to their profession, and were then di- vided into straddle chest compression or conventional chest compression group using the sequential numbered, opaque, sealed envelope random sampling method through block- of-four randomization. All participants studied a diagram showing the technique of chest compression. The Ethics committee of Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand approved of this study in terms of Human Rights Related to Research In- volving Human Subjects (Ethics code: MURA2017/23). 2.2. Participants The participants in this study were emergency physicians, general practitioners, nurses, ambulance staff, and medi- cal and paramedic students of Faculty of Medicine Ramathi- bodi Hospital. Airline staff, flight attendants, and cabin crew members of the Airports of Thailand Public Company Lim- ited (AOT) were also included. The exclusion criteria were participants who discontinued chest compression due to in- jury and occurrence of any problems for the study devices during the study. 2.3. Data gathering All participants’ characteristics including: age, sex, body mass index, occupation, previous BLS training, previous ex- perience in chest compression, and number of exercises per month were recorded. Vital signs of participants including their systolic blood pressure, pulse rate, and respiratory rate were measured immediately both before and after the proce- dure. Participants in each group pressed down on the chest of Laerdal® Resusci Anne manikin model connected with the ZOLL® X Series® monitor defibrillator and CPR Stat-Padz® Multi-Function electrode pads that provided continuous and summarized recording of chest compression quality. Partici- pants were blinded to the real-time quality results while per- forming chest compression to reduce potential bias. They were required to perform continuous compressions on the chest without stopping until they felt too tired to continue, this period did not exceed 4 minutes. The following vari- ables were recorded for both conventional and straddle chest compression techniques: overall mean compression rate and overall mean compression depth. Mean compression rate and mean compression depth were also recorded at each specific time interval (minutes 0-1, 1-2, 2-3 and 3-4, respec- tively). 2.4. Statistical Analysis In accordance with the study by Lei Z and Qing H (19), which compared the quality of conventional chest compression on the floor and straddle chest compression on the moving am- bulance stretcher using a manikin model, the sample size was calculated using STATA version 12.0 (StataCorp, College Station, TX, USA). We performed two-sample comparisons of the mean with a power of 0.9, sample size ratio of 1:1, P-value of 0.05, and two-sided tests. The minimum required sample was 124 participants. The data were recorded using Microsoft Excel 2010 (Microsoft Corporation, Redmond, WA, USA) and were analyzed using STATA version 14.0. Chi-square or exact probability test were applied to compare independent cate- gorical variables, while independent t-test were used to com- pare continuous variables. Paired t-test or Wilcoxon signed- rank test were used to compare dependent continuous vari- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 3 Archives of Academic Emergency Medicine. 2021; 9(1): e4 ables according to data distribution. P-value of <0.05 was considered statistically significant. 3. Results 3.1. Baseline characteristics of participants There were 124 enrolled participants in this study, which consisted of 111 (89.5%) individuals in the healthcare profes- sions and 13 (10.5%) in non-healthcare professions. Nobody discontinued the chest compression to be excluded. Partic- ipants were divided into 2 groups; 60 in the conventional chest compression and 64 in the straddle chest compression group. Differences in baseline characteristics were not statis- tically significant between the two groups (table 1). 3.2. Comparisons As shown in table 2, there were no statistically significant dif- ference in the quality of chest compression in terms of the overall mean compression rate (p = 0.863) and depth (p = 0.830). The fatigue associated with conventional and straddle chest compression were assessed by measuring the partici- pants’ vital signs before and after performing the compres- sion. Although the systolic blood pressure, pulse rate, and respiratory rate were significantly different before and after performing the compression in both groups, the differences were not clinically significant (table 3). 4. Discussion Chest compression is a lifesaving procedure, which increases survival rate among cardiac arrest patients, especially in out- of-hospital cardiac arrest (OHCA), where survival rate is low. According to recommendations of the American Heart Asso- ciation (AHA) in 2015, patients with cardiac arrest must be immediately resuscitated by performing high-quality chest compression with a compression rate of about 100-120 com- pressions per minute, compression depth should be between 2-2.5 inches or 5-6 centimeters. The chest should be released and allowed to completely recoil before initiating another compression and unnecessary interruptions should not oc- cur in performance of chest compression. Conventional chest compression by kneeling or positioning lateral to the patient’s side may be difficult and inappropriate in places such as an aircraft or high-speed moving ambulance, where the spaces are confined or limited. Straddle chest compres- sion is an alternative method, which allows for rescuers to continue chest compression without unnecessary interrup- tion. In the present study, which aimed to compare the quality of straddle and conventional chest compression tech- nique on a manikin model, the results revealed that there are no statistically significant differences in compression rate or depth between the two techniques neither overall nor at each specific time point (minutes 0-1, 1-2, 2-3 and 3-4, re- spectively). The overall mean compression rate (throughout the 4-minute evaluation period) was not significantly differ- ent between the two groups (125 compressions/min in con- ventional and 126 compressions/min in straddle technique), which were faster than the standard recommendation by the AHA2015 (100–120 compressions/min). The overall mean compression depth was also not significantly different be- tween the two groups (43.80 ± 9.60 mm in conventional and 43.90 ± 9.10 mm in straddle technique). The compression depth of both techniques was lower than the standard rec- ommendation by the AHA2015 (50–60 mm). These key re- sults suggest for further training to maintain high quality chest compression in rescuers, both those in healthcare pro- fessions and those in non-healthcare professions. The par- ticipants’ comfort and fatigue were assessed by measuring changes in their vital signs, there were no statistically sig- nificant differences in these regards between the two tech- niques. However, vital signs slightly increased after perform- ing chest compressions in both groups but they were not clinically significant. In a previous study by Handley AJ and Handley JA (17), which aimed to compare the quality of per- forming chest compressions in a narrow area by two tech- niques: straddle over the head and straddle over the body, the result revealed that the two alternative techniques were useful in situations where space was limited. Lei Z and Qing H (19) also compared the quality of standard chest compres- sion performed on the floor and straddle chest compression performed on a stretcher using a manikin model. The result showed no difference in chest compression quality between these two compression techniques. Straddle chest compres- sion can be performed both in-hospital and out-of-hospital depending on the situation. For patients with in-hospital car- diac arrest, straddle chest compression can be performed on the stretcher while transporting patients to operating the- ater or catheterization laboratory. Straddle chest compres- sion can also be performed for out-of-hospital cardiac arrest patients who are in a confined space or who are in moving ambulances due to the need for immediate transport to re- ceive definite treatment. 5. Limitation Our study has some limitations. First of all, a manikin model is unrealistic so the result of study must be cautiously inter- preted and may not be generalizable to real clinical situa- tions. Second, most of the participants were in the healthcare profession with variations in terms of experience and skills so the study’s results may not be generalizable to real-life res- cuers that consists of both healthcare and non-healthcare workers who will encounter out-of-hospital cardiac arrest patients. Third, the experiment was conducted by placing This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem P. Supatanakij et al. 4 Table 1: Comparing the baseline characteristics of participants between conventional and straddle chest compression group Characteristics Conventional (n = 60) Straddle (n = 64) P-value Age (years) Mean ± SD 25.77 ± 6.60 27.58 ± 7.21 0.149 Gender Male 40 (66.67) 40 (62.50) 0.708 Female 20 (33.33) 24 (37.50) BMI (kg/m2) Mean ± SD 23.69 ± 5.11 22.76 ± 4.55 0.286 Occupation Healthcare 54 (90.00) 57 (89.06) 0.893 Non-healthcare 6 (10.00) 7 (10.94) Previous BLS training Yes 44 (73.33) 52 (81.25) 0.390 No 16 (26.67) 12 (18.75) Previous experience in chest compression Yes 39 (65.00) 45 (70.31) 0.568 No 21 (35.00) 19 (29.69) Exercise for physical fitness (/month) 0 18 (30.00) 14 (21.88) 1-4 times 36 (60.00) 46 (71.88) 0.408 ≥ 5 times 6 (10.00) 4 (6.25) Data are presented as mean ± standard deviation or number (%). BMI: body mass index; BLS: basic life support. Table 2: Comparison of quality of chest compression between conventional and straddle chest compression techniques Variable Conventional (n = 60) Straddle (n = 64) P-value Compression (compressions per minute) Overall 126.18 ± 17.11 127.01 ± 21.01 0.811 Minute 0-1 126.89 ± 17.18 127.47 ± 19.95 0.863 Minute 1-2 125.97 ± 17.47 125.84 ± 20.56 0.971 Minute 2-3 124.23 ± 16.59 126.02 ± 20.32 0.634 Minute 3-4 124.43 ± 17.72 121.81 ± 17.62 0.539 Compression depth (millimeters) Overall 43.80 ± 9.60 43.40 ± 9.10 0.830 Minute 0-1 45.60 ± 8.10 45.70 ± 8.60 0.945 Minute 1-2 43.18 ± 9.83 43.00 ± 9.70 0.937 Minute 2-3 41.89 ± 11.14 39.76 ± 10.07 0.325 Minute 3-4 39.90 ± 11.27 39.20 ± 10.07 0.767 Data are presented as mean ± standard deviation. Table 3: Comparison of vital signs before and after chest compression between conventional and straddle chest compression techniques Vital signs Conventional (n = 60) Straddle (n = 64) Before After P Before After P SBP (mmHg) 125.5 ± 18.2 132.8 ± 7.5 <0.001 120.8 ± 5.1 131.8 ± 3.7 <0.001 PR (/min) 83.5 ± 18.2 93.6 ± 15.4 <0.001 79.9 ± 13.9 93.15 ± 16.7 <0.001 RR (/min) 16.6 ± 1.0 23.9 ± 3.4 <0.001 16.3 ± 0.7 23.7 ± 3.7 <0.001 Data are presented as mean ± standard deviation. SBP: systolic blood pressure; PR: pulse rate; RR: respiratory rate. the manikin on the floor, not on a stretcher in a moving am- bulance. Thus, the result may not be the same in a situation that chest compression must be continued while transport- ing the patients. 6. Conclusion The present study showed that the quality of chest compres- sion using straddle technique was as good as conventional technique. No significant differences were found in the qual- ity of chest compression or the participants’ comfort and fa- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: http://journals.sbmu.ac.ir/aaem 5 Archives of Academic Emergency Medicine. 2021; 9(1): e4 tigue levels. 7. Declarations 7.1. Acknowledgements We thank Angela Morben, DVM, ELS, from Edanz Group (https://en-author-services. edanzgroup.com), for editing a draft of this manuscript. 7.2. Author contribution PS, TC and CY conceived and designed the experiment, and defined the intellectual content; TC and PS performed the literature search; TC, PS, JP and PK performed the experi- ment and collected the data; CJ and CY performed the statis- tical analysis and data interpretation; PS, CJ and CY drafted the manuscript. All authors reviewed and approved the final draft of manuscript. 7.3. Funding/Support None. 7.4. 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