01ResearchImpact of hand dominance on effectiveness of chest compressionsin a simulated setting: a randomised, crossover trialJamie Cross BHSc(Paramedicine), is a paramedic1; Tommy Lam BHSc(Paramedicine), is a paramedic1; Joel Arndell BHSc(Paramedicine), is aparamedic1; John Quach BHSc(Paramedicine), is a paramedic1; Buck Reed MIHM, GradCertHltMgmt, BCA, DipParamedicSci is Associate Lecturerin Paramedicine1; Liz Thyer PhD, BSc(Hons), DipAmbParaStudies, GCTE is Senior Lecturer in Paramedicine1; Paul Simpson PhD, MScM(ClinEpi),GCClinEd, GCPaeds, BEd, BHSc(PrehospCare), AdvDipParaSci, ICP is Senior Lecturer and Director of Academic Program (Paramedicine)1Affiliations:1Western Sydney University, New South Waleshttps://doi.org/10.33151/ajp.16.672AbstractAimExternal cardiac compressions (ECC) are a critical component in determining the effectiveness of cardiopulmonary resuscitation (CPR).Guidelines prior to the 2010 International Liaison Committee on Resuscitation directed rescuers to place the heel of the dominant handdirectly on the chest when performing ECC, however current guidelines are silent on this issue. Existing research is inconsistent in findings,and heterogeneous in design and participants. The aims of this pilot study were to: 1) investigate the impact of hand dominance oneffectiveness of ECC; and 2) generate outcome data to inform sample size calculations for a larger future study.MethodsThis study utilised a single blinded, prospective randomised crossover trial design. Each participant was allocated to a ‘dominant handon chest’ (DHOC) or ‘non-dominant hand on chest’ (NDHOC) group. On a simulation manikin, participants in the DHOC group performed3 minutes of ECC with dominant hand on the chest and non-dominant hand supporting, followed by a ‘rest and recovery’ period andthen a second 3-minute period of ECC with the hand reversed such that the non-dominant hand was on the chest. The NDHOC groupperformed the same series of compressions but in reverse order. The primary outcome measure was effectiveness of ECC, determined bya percentage-based ‘CPR score’ (‘CS’). Secondary outcomes were compression depth, rate and release. The Wilcoxon rank-sum (MannWhitney) test was used due to the non-normal distribution of the data. Due to the crossover design, hierarchical linear regression was usedto assess for a period or cross over effect.ResultsFor the primary outcome of this study, we have found no significant difference in CS between DHOC and NDHOC (69.9% (SD=29.9) vs.69.1% (SD=34.1); p=0.92), respectively. There were no differences in the secondary outcomes of compression rate and depth, thoughcompression release was improved in the DHOC group (53% vs. 42%; p=0.02).ConclusionIn this randomised crossover study conducted in a simulation context there was no difference in ECC effectiveness measured by anoverall effectiveness outcome according to placement of the dominant or non-dominant hand on the chest during compressions. A modestimprovement in ECC release was seen in the dominant hand on chest group. While the study was underpowered, the results support anapproach involving rescuers placing whichever hand they are most comfortable with on the chest irrespective of handedness.Keywords:resuscitation; paramedic; effectiveness; external chest compressions; hand dominanceCorresponding Author: Paul Simpson, p.simpson@westernsydney.edu.au02IntroductionExternal cardiac compressions (ECC) are a critical componentin determining the effectiveness of cardiopulmonaryresuscitation (CPR) (1). ECCs provide a vital temporarycirculation that may sustain cerebral and myocardial perfusionduring sudden cardiac arrest, potentially contributing toreduced cerebral damage and increased likelihood ofsuccessful defibrillation.The role of ECCs in cardiac arrest and its association withimproved survival outcomes has become clearer over thepast decade, with the 2010 and 2015 International LiaisonCommittee on Resuscitation placing an increased emphasison early, high-quality and uninterrupted compressions in botha basic and advanced life support context (1,2). While theguidelines provide explicit recommendations regarding thevarious components of ECC such as compression rate, depth,recoil and hand position, they are silent on the issue of whetherto have the dominant or non-dominant hand placed directlyon the chest. Prior to 2010, it was recommended that the heelof the dominant hand be placed on the chest, and the nondominant on top to support (3).While it seems intuitive that a person preparing to performECC would place their dominant hand on the chest, evidencesuggests this may not always be the case. In a study of 383novice rescuers in Korea of whom 99% were right-handed(right dominant), 46% chose to position their non-dominanthand on the chest when given the choice in a simulated setting(4). It is also intuitive to suggest that ECC, as with many othermotor skills or tasks, might be more efficiently performed withthe dominant hand, given that the dominant side of the bodyfor the majority of people might be perceived to have greaterstrength, coordination and control.The current evidence describing the role of the dominant ornon-dominant hand on the chest during ECC and impact oneffectiveness is inconsistent. Only a single study has exploredwhether the issue of handedness impacts overall ECCquality (5). Using an objective manual assessment process,no difference was found between the dominant and nondominant hand position. The remaining studies contributingto the existing body of evidence focussed on individualcomponents of ECC, mainly compression rate, depth andrelease (recoil) (4,6-9). Comparability of results across thissmall body of evidence is difficult due marked heterogeneityin setting, design, participant groups and, in particular, thetype of ECC being used as the intervention. The durations ofECC performed are highly variable, while some include CPR(compressions and ventilation) performed in pairs or singlerescuers.Against this uncertainty in evidence, further research wasjustified and hence we conducted a crossover randomisedcontrolled trial on a population of student paramedics enrolledin an undergraduate paramedicine program at an Australianuniversity. Our study sought to answer the following primaryresearch question: In a simulated setting consisting of amanikin patient, does performing ECC with the dominanthand on the chest, compared to non-dominant hand on chest(NDHOC), increase effectiveness of ECC measured by anaccelerometer-based ‘CPR’ primary outcome score?MethodsThis study utilised a single blinded, prospective randomisedcrossover trial methodology and was conducted at WesternSydney University in a simulated setting. Data were collectedbetween June and December 2016.Participants and recruitmentParticipants were university students at Western SydneyUniversity. Participants were eligible if they held a valid first-aidcertificate and were enrolled in a clinical health science degree(paramedicine, podiatry, physiotherapy, occupational therapy).Recruitment took place via promotion of the study on socialmedia pages, posters at paramedic conferences and publicannouncements. Participants were asked to participate in astudy exploring general CPR performance but were blindedto the specific research question at any stage to reduce thechance of performance bias.Study outcomesThe primary outcome was ‘ECC effectiveness’ determined bya ‘CPR score’ (‘CS’). A more detailed explanation of the CScan be accessed at http://cdn.laerdal.com/downloads-test/f3784/Att_2_to_00021778.pdf The CS was produced by anaccelerometer-based ECC measurement device within aLaerdel Resusci-Anne ALS™ simulation manikin (LaerdalMedical, Stavanger, Norway). The CS is a composite measureof ECC performance that calculates the effectiveness ofcompression as a percentage figure, based on parameterswithin the 2010 American Heart Association resuscitationguidelines (11). Using a proprietary algorithm, the CS iscalculate by incorporating measurements of the followingindividual components of ECC: compression depth (% ofECC in which correct depth of compression of at least 5 cmis achieved); rate (% of compressions performed at correctrate between the range of 100-120 per minute); compressionrelease (% of compressions where complete release [recoil]is achieved); hand position (% of compressions where handposition was correct); and number of compressions percycle (12). Of these, the components of compression depth,compression rate and compression release were consideredrelevant to the impact of hand dominance and were analysedindependently and are presented as secondary outcomes.Sample sizeReview of the existing literature investigating the impact ofCross: Chest compressions: impact of hand dominanceAustralasian Journal of Paramedicine: 2019;1603Cross: Chest compressions: impact of hand dominanceAustralasian Journal of Paramedicine: 2019;16hand dominance on ECC effectiveness found reporteddifferences between groups to be quite variable and insufficientfor performing sample size calculations for an appropriatelypowered larger study. Therefore, this study was conductedas a pilot study, to generate preliminary results data on whicha reliable sample size calculation for the future study couldbe based. As such, no statistical sample size calculation wasperformed for this present study. A pragmatic enrolment targetof 80 participants was set in advance based on funding andlogistical considerations associated with this research project.Study process and data collectionAfter recruitment, participants were required to completean information form providing demographic details andinformation on the following potential confounding variables:age (years); gender (M/F); previous ‘real’ ECC experience(having performed ECC in a live clinical setting as a bystanderor health professional) (Y/N). Three questions designed toelicit hand dominance without participants being aware thatthis was an important factor were also included: ‘What handdo you throw with?’; ‘What hand do you hold a tennis racquetwith?’; and ‘What hand do you write with?’ As stated previously,participants were blinded to the research question and studyoutcomes.Following confirmation of eligibility, participants were allocatedrandomly to one of two groups: ‘dominant hand on chest’or ‘non-dominant hand on chest’. Group allocation wasdetermined by a computer-generated randomisation schedulecreated using Microsoft Excel 2010. Allocation concealmentwas guaranteed by the use of sequentially numbered sealedopaque envelopes. An envelope for each participant was notopened until after a participant’s enrolment in the study wasconfirmed. This allocation determined the sequence in whichtwo periods of ECC were performed by each participant.Participants were asked to approach the manikin from theanatomical left side, and based on the group allocation wereinstructed which hand to have in contact with the chest asthey prepared to commence ECC. Each participant performedtwo periods of ECC (no ventilations), each of three minutesduration, with a ‘rest and recovery’ period of at least 15 minutesin between. Those allocated to the DHOC group performed thefirst period of ECC with the dominant hand in contact with thechest and the non-dominant hand supporting on top of it, thenreversed that hand position for second ECC period. Those inthe NDHOC group performed their two periods of ECC in theopposite sequence, still with a rest and recovery period.Data analysisData were analysed by a biostatistician blinded to groupallocation. Analysis was performed using Stata© version 13(StataCorp. 2014. Stata Statistical Software: Release 13.College Station, TX: StataCorp LP). Only paired data wereincluded in the final analysis (that is, when a participantcompleted both DHOC and NDHOC phases of ECC).Descriptive statistics were generated, and differences betweenprimary and secondary outcomes were assessed usingnon-parametric tests (two sample Wilcoxon rank-sum (MannWhitney)) due to the non-normal distribution of the data.Statistical significance was established at p
