Assessment Task 3: Essay - critical appraisal of evidence
To demonstrate your ability to critically appraise a piece of published evidence in relation to a clinical issue. UsingCritical Appraisal Skills Programme (CASP), you will demonstrate the ability to critically appraise the design and methods of a systematic review or randomised controlled trial, highlighting the strengths and weaknesses of the study.
01 Research Impact of hand dominance on effectiveness of chest compressions in a simulated setting: a randomised, crossover trial Jamie Cross BHSc(Paramedicine), is a paramedic1; Tommy Lam BHSc(Paramedicine), is a paramedic1; Joel Arndell BHSc(Paramedicine), is a paramedic1; John Quach BHSc(Paramedicine), is a paramedic1; Buck Reed MIHM, GradCertHltMgmt, BCA, DipParamedicSci is Associate Lecturer in 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)1 Affiliations: 1Western Sydney University, New South Wales https://doi.org/10.33151/ajp.16.672 Abstract Aim External 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 hand directly 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 on effectiveness of ECC; and 2) generate outcome data to inform sample size calculations for a larger future study. Methods This study utilised a single blinded, prospective randomised crossover trial design. Each participant was allocated to a ‘dominant hand on chest’ (DHOC) or ‘non-dominant hand on chest’ (NDHOC) group. On a simulation manikin, participants in the DHOC group performed 3 minutes of ECC with dominant hand on the chest and non-dominant hand supporting, followed by a ‘rest and recovery’ period and then a second 3-minute period of ECC with the hand reversed such that the non-dominant hand was on the chest. The NDHOC group performed the same series of compressions but in reverse order. The primary outcome measure was effectiveness of ECC, determined by a percentage-based ‘CPR score’ (‘CS’). Secondary outcomes were compression depth, rate and release. The Wilcoxon rank-sum (Mann- Whitney) test was used due to the non-normal distribution of the data. Due to the crossover design, hierarchical linear regression was used to assess for a period or cross over effect. Results For 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, though compression release was improved in the DHOC group (53% vs. 42%; p=0.02). Conclusion In this randomised crossover study conducted in a simulation context there was no difference in ECC effectiveness measured by an overall effectiveness outcome according to placement of the dominant or non-dominant hand on the chest during compressions. A modest improvement in ECC release was seen in the dominant hand on chest group. While the study was underpowered, the results support an approach involving rescuers placing whichever hand they are most comfortable with on the chest irrespective of handedness. Keywords: resuscitation; paramedic; effectiveness; external chest compressions; hand dominance Corresponding Author: Paul Simpson,
[email protected] 02 Introduction External cardiac compressions (ECC) are a critical component in determining the effectiveness of cardiopulmonary resuscitation (CPR) (1). ECCs provide a vital temporary circulation that may sustain cerebral and myocardial perfusion during sudden cardiac arrest, potentially contributing to reduced cerebral damage and increased likelihood of successful defibrillation. The role of ECCs in cardiac arrest and its association with improved survival outcomes has become clearer over the past decade, with the 2010 and 2015 International Liaison Committee on Resuscitation placing an increased emphasis on early, high-quality and uninterrupted compressions in both a basic and advanced life support context (1,2). While the guidelines provide explicit recommendations regarding the various components of ECC such as compression rate, depth, recoil and hand position, they are silent on the issue of whether to have the dominant or non-dominant hand placed directly on the chest. Prior to 2010, it was recommended that the heel of the dominant hand be placed on the chest, and the non- dominant on top to support (3). While it seems intuitive that a person preparing to perform ECC would place their dominant hand on the chest, evidence suggests this may not always be the case. In a study of 383 novice rescuers in Korea of whom 99% were right-handed (right dominant), 46% chose to position their non-dominant hand on the chest when given the choice in a simulated setting (4). It is also intuitive to suggest that ECC, as with many other motor skills or tasks, might be more efficiently performed with the dominant hand, given that the dominant side of the body for the majority of people might be perceived to have greater strength, coordination and control. The current evidence describing the role of the dominant or non-dominant hand on the chest during ECC and impact on effectiveness is inconsistent. Only a single study has explored whether the issue of handedness impacts overall ECC quality (5). Using an objective manual assessment process, no difference was found between the dominant and non- dominant hand position. The remaining studies contributing to the existing body of evidence focussed on individual components of ECC, mainly compression rate, depth and release (recoil) (4,6-9). Comparability of results across this small body of evidence is difficult due marked heterogeneity in setting, design, participant groups and, in particular, the type of ECC being used as the intervention. The durations of ECC performed are highly variable, while some include CPR (compressions and ventilation) performed in pairs or single rescuers. Against this uncertainty in evidence, further research was justified and hence we conducted a crossover randomised controlled trial on a population of student paramedics enrolled in an undergraduate paramedicine program at an Australian university. Our study sought to answer the following primary research question: In a simulated setting consisting of a manikin patient, does performing ECC with the dominant hand on the chest, compared to non-dominant hand on chest (NDHOC), increase effectiveness of ECC measured by an accelerometer-based ‘CPR’ primary outcome score? Methods This study utilised a single blinded, prospective randomised crossover trial methodology and was conducted at Western Sydney University in a simulated setting. Data were collected between June and December 2016. Participants and recruitment Participants were university students at Western Sydney University. Participants were eligible if they held a valid first-aid certificate and were enrolled in a clinical health science degree (paramedicine, podiatry, physiotherapy, occupational therapy). Recruitment took place via promotion of the study on social media pages, posters at paramedic conferences and public announcements. Participants were asked to participate in a study exploring general CPR performance but were blinded to the specific research question at any stage to reduce the chance of performance bias. Study outcomes The primary outcome was ‘ECC effectiveness’ determined by a ‘CPR score’ (‘CS’). A more detailed explanation of the CS can be accessed at http://cdn.laerdal.com/downloads-test/ f3784/Att_2_to_00021778.pdf The CS was produced by an accelerometer-based ECC measurement device within a Laerdel Resusci-Anne ALS™ simulation manikin (Laerdal Medical, Stavanger, Norway). The CS is a composite measure of ECC performance that calculates the effectiveness of compression as a percentage figure, based on parameters within the 2010 American Heart Association resuscitation guidelines (11). Using a proprietary algorithm, the CS is calculate by incorporating measurements of the following individual components of ECC: compression depth (% of ECC in which correct depth of compression of at least 5 cm is achieved); rate (% of compressions performed at correct rate between the range of 100-120 per minute); compression release (% of compressions where complete release [recoil] is achieved); hand position (% of compressions where hand position was correct); and number of compressions per cycle (12). Of these, the components of compression depth, compression rate and compression release were considered relevant to the impact of hand dominance and were analysed independently and are presented as secondary outcomes. Sample size Review of the existing literature investigating the impact of Cross: Chest compressions: impact of hand dominance Australasian Journal of Paramedicine: 2019;16 03 Cross: Chest compressions: impact of hand dominance Australasian Journal of Paramedicine: 2019;16 hand dominance on ECC effectiveness found reported differences between groups to be quite variable and insufficient for performing sample size calculations for an appropriately powered larger study. Therefore, this study was conducted as a pilot study, to generate preliminary results data on which a reliable sample size calculation for the future study could be based. As such, no statistical sample size calculation was performed for this present study. A pragmatic enrolment target of 80 participants was set in advance based on funding and logistical considerations associated with this research project. Study process and data collection After recruitment, participants were required to complete an information form providing demographic details and information 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 bystander or health professional) (Y/N). Three questions designed to elicit hand dominance without participants being aware that this was an important factor were also included: ‘What hand do you throw with?’; ‘What hand do you hold a tennis racquet with?’; and ‘What hand do you write with?’ As stated previously, participants were blinded to the research question and study outcomes. Following confirmation of eligibility, participants were allocated randomly to one of two groups: ‘dominant hand on chest’ or ‘non-dominant hand on chest’. Group allocation was determined by a computer-generated randomisation schedule created using Microsoft Excel 2010. Allocation concealment was guaranteed by the use of sequentially numbered sealed opaque envelopes. An envelope for each participant was not opened until after a participant’s enrolment in the study was confirmed. This allocation determined the sequence in which two periods of ECC were performed by each participant. Participants were asked to approach the manikin from the anatomical left side, and based on the group allocation were instructed which hand to have in contact with the chest as they prepared to commence ECC. Each participant performed two periods of ECC (no ventilations), each of three minutes duration, with a ‘rest and recovery’ period of at least 15 minutes in between. Those allocated to the DHOC group performed the first period of ECC with the dominant hand in contact with the chest and the non-dominant hand supporting on top of it, then reversed that hand position