Computational protocol: Effect of the rate of chest compression familiarised in previous training on the depth of chest compression during metronome-guided cardiopulmonary resuscitation: a randomised crossover trial

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Protocol publication

[…] This study was performed under the approval of the CHA University Bundang Medical Center Institutional Review Board (IRB approval # BD2014-019, 2 February 2014). This was a single-blinded, randomised, prospective crossover trial of simulated, one-person, chest-compression-only CPR.The study was performed at the CHA University Bundang Medical Center, Gyeonggi-Do, Korea, from March 2014 to February 2015. We enrolled senior students of a medical school (CHA University) and two paramedic schools (Seojeong College and Eulji University) who, within the previous year, had finished two sessions of regular CPR training courses based on the American Heart Association (AHA) Basic Life Support course according to the 2010 AHA guidelines for CPR and emergency cardiovascular care. Any student who declined to participate in the study for any reason was excluded. Written informed consent was obtained from every participant.A ResusciAnne manikin with a PC skill-reporting system (Laerdal, Stavanger, Norway) was used to measure and record CPR data. Chest compression guiding sounds at speeds of 100, 120 and 140 compressions/min were synthesised using Reason audio synthesis software (Propellerhead, Stockholm, Sweden).The experimental procedure consisted of three trials with two phases: a training phase for the participants to become accustomed to a certain chest compression rate, and a measuring phase to measure the quality of chest compressions while performing CPR following metronome guidance at a conventional rate of chest compression (120/min). The participants practised chest-compression-only CPR following the metronome-guided sound at a rate randomly selected from 100, 120 or 140 compressions/min for 2 h as a training phase. Randomised selection of a rate was based on a random number table generated by Microsoft Office Excel 2010 (Redmond, Washington, USA). The rate and the depth of chest compression without metronome guidance were measured for 1 min shortly after the practice. After 1 h of rest, the participants performed chest compression-only CPR for 1 min following the metronome-guided sound at a rate of 120 compressions/min, and their quality was measured. This was the first trial. As the training phase for the second trial, the participants again performed chest compression-only CPR following the metronome-guided sound at a rate randomly selected between the two not selected in the first trial. Then the rest of the trial was repeated. For the third trial, a training phase was performed using the guiding sound at the rate unselected in the prior two trials. The duration of the interval between each trial was guaranteed to be least 2 days to prevent a possible interaction of different chest compression rates practised in each training phase (). Only one participant was included at a time in each trial. The rate of metronome guidance used in every trial was blinded to the participants.The sex, age, body weight and height of the participants were collected. Average compression depth (ACD, mm), average compression rate (ACR, counts/min), duty cycle (%), and the fractions of chest compressions with incomplete release and incorrect hand position (%) were measured and recorded during the measuring phase of the procedure using the PC skill-reporting system.The data following a normal distribution were described as mean±SD, and non-parametric data were described as median (IQR). A repeated measures analysis of variance (ANOVA) was conducted to compare normally distributed variables, and a paired t-test with a Bonferroni correction was performed as a post hoc test. A Friedman test was used to compare non-normally distributed variables, and a Wilcoxon signed rank test with Bonferroni correction was performed as a post hoc test. Statistical significance was set at p<0.05, which was calculated from a two-sided test, if applicable. A sample size of 32 was required to have sufficient power to detect a significant difference in the ACD of each trial using repeated measure ANOVA (effect size f=0.25, power=0.80). Microsoft Office Excel 2010 was used to record and analyse data, and IBM SPSS Statistics 21.0 (IBM Corp., Armonk, New York, USA) was used for statistical calculations. R V.3.1.3 (R-project, http://www.r-project.org) was used to build a parallel-coordinates plot and a box plot of the between-group difference for visualising the results of Friedman's test. G*Power 3.1 (Heinlich-Heine Universität, Düsseldorf, Germany) was used to calculate the sample size. […]

Pipeline specifications

Software tools SPSS, G*Power
Application Miscellaneous
Organisms Homo sapiens