CPR performance in lay people with telephone assisted CPR instructions – A prospective manikin-based observational study.

It has been reported that Emergency Medical Services (EMS) in Europe, annually encounter about 275,000 out-of-hospital cardiac arrests (OHCA), whilst in the United States (US) this number rises to 420,000.¹ Sixty-five to 70 percent of all sudden cardiac deaths (SCDs) are attributable to coronary heart disease (CHD), however, the frequency of CHD is much lower in SCDs occurring under the age of 40.^2-3 Ten percent of SCDs are due to other types of structural heart disease including congenital coronary artery anomalies, myocarditis, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy.^2-4Structural heart disease is much higher in subjects under the age of 30. Five to 10 percent of SCDs are arrhythmic, occurring in the absence of structural heart disease such as long QT syndrome, Brugada syndrome, Wolff-Parkinson-White syndrome and catecholaminergic polymorphic ventricular tachycardia (VT).^3-4 In the absence of any structural abnormality or electrophysiologic abnormality on the ECG, these entities are often termed primary electrical disease.^5-7 Fifteen to 25 percent of cardiac arrests are noncardiac in origin. These include trauma, bleeding, drug intoxication, intracranial haemorrhage, pulmonary embolism, near-drowning, and central airway obstruction.^5-8 Survival rates have been reported to be poor with a survival to hospital discharge of less than 10%.⁹ According to our local cardiac arrest registry, in Malta survival to hospital discharge is around 3%.¹⁰

The chance of survival from an OHCA is dependent on the recognition of cardiac arrest by Emergency Medical Dispatchers’ (EMDs), early bystander cardiopulmonary resuscitation (CPR), and early defibrillation.¹¹To-date, in order to increase bystander intervention, millions of laypeople (non-specialists within the general public) have undergone CPR training, and AEDs have been widely disseminated in the community.¹² Despite these efforts, many OHCA patients still fail to receive bystander intervention,^11,13 and it is estimated that 65% of CPR-trained bystanders will fail to provide CPR.¹⁴ In Malta the rate of bystander CPR is around 38%.¹⁰ Similarly, in the United Kingdom (UK) the rate of bystander CPR is around 40%.¹⁵ Impediments to initiating CPR include panic, fear of causing harm, not performing CPR adequately (even for those who have received CPR training or have performed CPR in the past),^14,16-18 and a reluctance to perform mouth-to-mouth ventilation.^19-20 Telephone assisted CPR (TCPR) by EMDs, is proven to be an effective and reasonable method to improve the rate of bystander-performed CPR.²¹ Furthermore, TCPR by EMDs (also known as dispatcher assisted CPR – DA-CPR) has been shown to double the frequency of bystander CPR,²² so much so that it has now obtained a key position in the 2015 ERC guidelines.²³

According to the 2015 European Resuscitation Guidelines (ERC), OHCA has occurred if a patient is unconscious and not breathing normally.²³ However, the ability to recognize OHCA over the phone can be challenging especially if agonal breathing occurs.^24-25 Despite this, recognition of OHCA by EMDs in certain European countries such as Finland, has been reported to be as high as 70–83%.^26-28 In Malta, EMDs do not yet have a standard protocol on TCPR but, nevertheless, provide TCPR in approximately 58% of OHCA victims.²⁹

The aim of this study was to test a set of TCPR instructions in Maltese on lay people with no previous knowledge of CPR, and assess the effectiveness and quality of the CPR provided.

Methods and Materials

A prospective, manikin-based observational study was conducted in Malta between July 2018 and July 2019. A set of TCPR instructions in Maltese was drawn up and tested on lay people with no previous knowledge of CPR. The primary endpoint was to check for understanding and correct execution of such instructions vis-à-vis hand positioning during chest compression, compressions depth and rate. Ethical approval was granted from the Faculty Research Ethics Committee (Ref no. FRECMDS_1718_061).

TCPR instructions in Maltese were created using commonly used language (Figure 1). These included instructions on the recognition of cardiac arrest and compression-only CPR. English TCPR instructions from the resuscitation academy were also used with permission as guidance (Figure 2).³⁰ Given that this study was manikin-based, instructions about the recognition of cardiac arrest were not tested, and only instructions relating to compressions-only CPR were assessed. Six experienced EMD’s were recruited and underwent training on how to deliver TCPR instructions.

Figure 1

All caller interview – Cardiac arrest recognition and TCPR instructions in Maltese

Figure 2

TCPR instructions in English used with permission from the Resuscitation Academy

Participants were recruited from 10 localities around Malta. With a population of around 441,000 people,³¹Malta is subdivided into five districts (Figure 3), each consisting of a number of localities. These include the Northern Harbour District, the Western District, the Northern District, the South Eastern District and the Southern Harbour District.³² Localities were invited to participate in the study via their respective local councils. Ten localities accepted to participate, two from each district (Figure 4). The inclusion criteria included age over 18 years of age and no previous CPR training. Each Local Council issued an open public invitation to its residents in the form of a poster, stating clearly the eligibility criteria (Figure 5). Attendance was voluntary and the authors had no part in the selection process of participants. Consent was obtained from all participants before data collection.

Figure 3

Districts of Malta and Gozo

Figure 4

Localities taking part in stud

Figure 5

Invitation poster used for recruitment of participants

Data was collected using Laerdal’s Resus Annie® QCPR manikin and SkillReporterTM (PC) software. Participants were asked to follow a set of compression-only CPR instructions in Maltese simulating a telephone call. Data was collected over one minute of compression-only CPR. Information about the correct hand position, depth of compressions, fully released compressions and mean rate of compressions were recorded and stored. Study investigators also noted the correct hand, elbow and shoulder positioning during the simulation. A depth of 50-60mm and a rate of 100-120/min was taken as the ‘correct’ standard reference.²³ For correct hand positioning, an arbitrary performance target of 90% or better was set. After data collection, all participants in each locality were trained in Basic Life Support and AED use by certified instructors.

Statistical analysis

Descriptive and inferential analyses were performed through a combination of Microsoft Office Professional Plus 2010 Excel and IBM SPSS Statistics version 22.   Details on how the variables were modelled are shown in Table 1.

A Kolmogorov-Smirnov test was performed to test the normality of the distribution for dependent continuous variables. Kruskal-Wallis test was used to identify if there were any statistically significant differences between the independent variables, age groups and district of residence, and the dependent variables, proportion of compressions with correct hand position, compressions fully released, deep enough compressions and mean rate of compressions.  Mann-Whitney U test was used to identify if there were any statistically significant differences between the independent variables, gender and education, and the dependent variables, proportion of compressions with correct hand position, compressions fully released, deep enough compressions and mean rate of compressions. One-way analysis of variance (ANOVA) was used to identify if there were any statistically significant differences between the independent variables, age groups and district of residence, and the dependent variable, mean depth of compressions.  Independent-samples t-test was used to identify if there were any statistically significant differences between the independent variables, gender and education, and the dependent variable, mean depth of compressions.

Results

The distribution of participants by age group, gender, highest educational attainment, and district of residence (based on Local Administrative Units Level 1) are shown in Table 2. Assuming a performance target of 90% or more, 64.5% (n=100) of the cohort performed compressions with the correct hand position and 73.6% (n=114) fully released their compressions appropriately.  Only 12.9% (n=20) of participants performed deep-enough compressions. The distribution of the overall performance of the recruited sample with regards to compressions with correct hand position, compressions fully released and deep-enough compressions are shown in Table 3. The distribution of the overall performance of the recruited sample for mean depth (mm) and mean rate (per minute) are shown in Tables 4 and 5, respectively.  With regards to mean depth of compressions, only 18.1 % (n=28) of the cohort achieved the recommended 50-60mm depth of compressions (Table 4). Just over half of the participants (53.5%, n=83) performed the compressions at the recommended rate of 100 – 120/min (Table 5).

The variable distribution of mean depth followed a normal distribution (Kolmogorov-Smirnov D test, D(155) = 0.064, p=0.200). In contrast, the variable distribution of compressions with correct hand position (D(155) = 0.360, p=<0.001), compressions fully released (D(155) = 0.300, p=<0.001), deep-enough compressions (D(155) = 0.323, p=<0.001) and mean rate (D(155) = 0.100, p=0.001) did not follow a normal distribution.

The distribution and univariate analyses between the sociodemographic variables and the various dependent continuous variables are shown in Tables 6-10.  There were no statistically significant differences between age groups, gender, education and district of residence in relation to compressions with the correct hand position (Table 6). Females were statistically significantly more likely to perform compressions which were fully released when compared to males (Mann-Whitney U test, U=2343.500, p=0.017).  No statistically significant differences were found however, between age groups, education and district of residence in relation to compressions which were fully released (Table 7). Males were statistically significantly more likely to perform deep enough compressions when compared to females (Mann-Whitney U test, U=2446.000, p=0.037) (Table 8).  Similarly, participants with tertiary education (Mann-Whitney U test, U=2388.500, p=0.016) and from the Western district (Kruskal-Wallis H test, χ²=15.468, p=0.004) were statistically significantly more likely to perform deep-enough compressions when compared to the rest (Table 8). No statistically significant difference was found however between age groups, and the proportion of deep-enough compressions. With regards to the mean depth of compressions, participants with tertiary education were statistically significantly more likely to have a higher average mean depth of compressions (Independent-samples t-test, t(153)=1.860, p=0.004). There were no statistically significant differences between age groups, gender and district of residence, in relation to mean depth of compressions (Table 9). Table 10 shows that participants with primary or secondary education were statistically significantly less likely to have a higher mean rate of compressions when compared to participants with tertiary education (Mann-Whitney U test, U = 2209.500, p=0.004). There were no statistically significant differences between age groups, gender and district of residence, in relation to mean rate of compressions (Table 10).

Discussion

The decision to use compression-only CPR instructions on lay people rather than the standard compressions with ventilations, was based on evidence from randomized controlled trials.^33-34 In a systematic review and meta-analysis by Cabrini et al., (2010), it was shown that compression-only CPR is superior to standard CPR at least when performed by untrained bystanders.³⁴ Other observational studies of bystander-initiated CPR comparing standard and compressions-only CPR reported similar survival rates.^35-37 Apart from survival rates, compression-only CPR instructions are easier to teach to lay persons during BLS courses and easily communicated by dispatchers under real conditions during TCPR.^20,34 Moreover, bystanders are more likely to accept and perform compressions-only CPR rather than standard CPR, since this avoids mouth-to-mouth contact.^19-20

The choice of words used during TCPR has been shown to be important in order to engage with the caller. Phrases like:

“Irridu nibdew CPR”

(we need to start CPR)

Has been associated with higher caller agreement. According to Riou et al., (2018), talking about bystander-CPR in terms of willingness (“want”, “be willing”, “would like”, “be happy to”) was associated with low caller agreement (43%).³⁸ On the other hand, talking about it in terms of futurity (“going to”, “will”) and/or obligation (“need”, “have to”) was associated with high caller agreement (97% and 84% respectively).³⁸

In this study, we showed that the phrases used for hand positioning during CPR:

“Poggi il-pala ta’ jdejk fin-nofs tas-sider”

(Put your hand on the centre of their chest)

Was understood and executed accurately by approximately 7 out of 10 rescuers with no previous background of CPR training. No statistical significance between age, gender, level of education and district of residence was found vis a vis correct hand positioning in our study. With regards to phrases about locking of fingers and elbow positioning:

“Poggi il-pala l’ohra fuq idejk u orbot subajk flimkien”

(Put your other hand on top of that hand and clasp your fingers together)

and

“Żomm minkbejk dritti”

(Keep your elbows straight)

This study found that all participants understood and executed these instructions accurately. Similarly, phrases about the rate of compressions:

“ibda għafas u għodd miegħi...1,2,3,4....Ibqa sejjer/sejra hekk. Tieqafx mhux ha taghmel hsara!”

(Keep pushing and count out loud…1,2,3,4…keep going, do not pause, you won’t cause any harm)

Was understood and accurately executed in 6 out of 10 rescuers adhering to the recommended 100-120/min compression rate. No statistical significance between age, gender and district of residence was found on rate of compressions. We opted not to use metronomes to help rescuers with their compression rate but counting repeatedly with them from 1 to 4 throughout the whole minute of CPR. In two separate studies, Park et al., (2013) and Scott et al., (2018), showed that rescuers receiving instructions with metronome assistance although performing better with correct compression rate had consistently shallower compression depth than those receiving instructions without metronome assistance.^39-40

When it came to phrases about depth:

“għafas l-isfel b'kemm għandek saħħa”

(Push down as hard as you can)

Only 2 out of 10 rescuers achieved the recommended 50-60mm depth, and the vast majority of participants achieved a depth less than 50mm. Overall males performed deeper compressions when compared to females, whilst rescuers with tertiary education and those living in the western district (Siġġiewi and Żebbug) had a significantly higher compression depth when compared to the rest. No statistical significance was found between age and depth of compressions. It is well documented in the literature that even with correct knowledge and feedback, rescuers often do not achieve adequate depth.^41-43 Moreover, physical fatigue,^44-45 overall rescuer’s physical fitness, height and weight ^46-47 all impact on the quality of depth of chest compressions. These variables might partly explain our findings that males were better than females at deeper compressions. The amount of power required to depress a sternum by 5 cm is about 500 N,⁴⁸ and it can be difficult to judge how much force is required to achieve 5cm of compression even for trained professionals. Data from two RCTs by Mirza et al., (2008), suggest that instructions to “push down as hard as you can” (“għafas l-isfel b'kemm għandek saħħa”) are superior to instructions to “push down firmly 2 inches (50mm)” in achieving improvement in chest compression depth.⁴⁹ 

Limitations

Manikin simulation cannot replicate the complexity, urgency and constraints of a real life scenario. Although participants were taken from the five main districts of Malta, the sample size was still small and Gożo, a separate district, was not included in this study. CPR efficiency by rescuers was not tested in this study since the main aim was to test understanding and execution of TCPR instructions in Maltese.

Conclusion

This study showed that, in Malta, laypeople with no previous CPR training can understand and execute a set of chest compression-only TCPR instructions in Maltese. The introduction of a standard operating procedure and training of EMDs on policy, expectations and performance is vital if bystander CPR and survival rates are to improve locally. Training coupled with quality improvement projects such as call collection for review, analysis and feedback is the way forward.

Acknowledgments

I would like to acknowledge the help of: Dr. Mary Rose Cassar MD, FRCS (Edin.) MMCFD, FERC; Dr. Luke Zammit MD, MRCEM; Dr. Francesca Spiteri MD, MRCEM; Dr. Daniele Lauretta Agius MD, MRCEM; Ms. Wendy Vassallo B.Sc. Nursing (Melita), M.Sc. (Edin); Ms. Eleonor Koustas B.Sc. Nursing; for their help in liaising with local councils and facilitating organisation of the CPR courses. I would also like to thank the Malta Resuscitation Council, for their support and for providing all the equipment necessary for this study. Last but not least, I would like to thank all Local Councils who took part in this study and facilitated the CPR courses

References

1. Atwood C, Eisenberg MS, Herlitz J, Rea TD. Incidence of EMS-treated out of-hospital cardiac arrest in Europe. Resuscitation 2005; 67:75–80.
2. Centers for Disease Control and Prevention (CDC). State-specific mortality from sudden cardiac death--United States, 1999. MMWR Morb Mortal Wkly Rep 2002; 51:123.
3. Zheng ZJ, Croft JB, Giles WH, Mensah GA. Sudden cardiac death in the United States, 1989 to 1998. Circulation 2001; 104:2158.
4. Eckart RE, Scoville SL, Campbell CL, Shry EA, Stajduhar KC, Potter RN et al. Sudden death in young adults: a 25-year review of autopsies in military recruits. Ann Intern Med 2004; 141:829.
5. Drory Y, Turetz Y, Hiss Y, Lev B, Fisman EZ, Pines A, et al. Sudden unexpected death in persons less than 40 years of age. Am J Cardiol 1991; 68:1388.
6. Chugh SS, Kelly KL, Titus JL. Sudden cardiac death with apparently normal heart. Circulation 2000; 102:649.
7. Consensus Statement of the Joint Steering Committees of the Unexplained Cardiac Arrest Registry of Europe and of the Idiopathic Ventricular Fibrillation Registry of the United States. Survivors of out-of-hospital cardiac arrest with apparently normal heart. Need for definition and standardized clinical evaluation. Circulation 1997; 95:265.
8. Kuisma M, Alaspää A. Out-of-hospital cardiac arrests of non-cardiac origin. Epidemiology and outcome. Eur Heart J 1997; 18:1122.
9. 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; 81:1479–1487.
10. Caruana M., Cassar MR. The registry for out of hospital cardiac arrest in Malta one year after implementation: An indicator of the strength of the chain of survival. Resuscitation 2012; Volume 83, Supplement 1, Page 48.
11. Wissenberg M, Lippert FK, Folke F, Weeke P, Hansen CM, Christensen EF, et al. Association of national initiatives to improve cardiac arrest management with rates of bystander intervention and patient survival after out-of-hospital cardiac arrest. JAMA. 2013; 310:1377–84.
12. Anderson ML, Cox M, Al-Khatib SM, Nichol G, Thomas KL, Chan PS, et al. Rates of cardiopulmonary resuscitation training in the United States. JAMA Intern Med. 2014; 174:194–201.
13. Chan PS, McNally B, Tang F, Kellermann A; Group CS. Recent trends in survival from out-of-hospital cardiac arrest in the United States. Circulation. 2014; 130:1876–1882.
14. Swor R, Khan I, Domeier R, Honeycutt L, Chu K, Compton S. CPR training and CPR performance: do CPR-trained bystanders perform CPR? Acad Emerg Med. 2006; 13:596–601.
15. Perkins GD, Lall R, Quinn T, Deakin CD, Cooke MW, Horton J et al. Mechanical versus manual chest compression for out-of-hospital cardiac arrest (PARAMEDIC): a pragmatic, cluster randomised controlled trial. Lancet 2015; 385:947-55.
16. Savastano S, Vanni V. Cardiopulmonary resuscitation in real life: the most frequent fears of lay rescuers. Resuscitation. 2011; 82:568–571.
17. Axelsson A, Herlitz J, Fridlund B. How bystanders perceive their cardiopulmonary resuscitation intervention; a qualitative study. Resuscitation. 2000; 47:71–81.
18. Moller TP, Hansen CM, Fjordholt M, Pedersen BD, Ostergaard D, Lippert FK. Debriefing bystanders of out-of-hospital cardiac arrest is valuable. Resuscitation. 2014; 85:1504–1511.
19. Locke CJ, Berg RA, Sanders Ab, Davis MF, Milander MM, Kern KB et al. Bystander cardiopulmonary resuscitation. Concerns about mouth-to-mouth contact. Arch Intern Med 1995; 155: 938-943.
20. Cho GC, Sohn YD, Kang KH, Lee WW, Lim KS, Kim W et al. The effect of basic life support education on laypersons’ willingness in performing bystander hands only cardiopulmonary resuscitation. Resuscitation 2010; 81: 691-694.
21. SongKJ, Shin SD, Park CB, Kim JY, Kim DK, Kim CH et al. Dispatcher-assisted bystander cardiopulmonary resuscitation in a metropolitan city: A before-after population-based study. Resuscitation 2014; 85(1):34–41
22. Rea TD, Eisenberg MS, Becker LJ, Murray JA, Hearne T. Temporal trends in sudden cardiac arrest: a 25-year emergency medical services perspective. Circulation. 2003; 107:2780–5.
23. Travers AH, Perkins GD, Berg RA, Castren M, Considine J, Escalante R et al. Part 3: Adult basic life support and automated external defibrillation: 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations. Resuscitation 2015; 95:e43–e69
24. Bang A, Herlitz J, Martinell S. Interaction between emergency medical dispatcher and caller in suspected out-of-hospital cardiac arrest calls with focus on agonal breathing. A review of 100 tape recordings of true cardiac arrest cases. Resuscitation. 2003; 56:25–34.
25. Bohm K, Rosenqvist M, Hollenberg J, Biber B, Engerstrom L, Svensson L. Dispatcher-assisted telephone-guided cardiopulmonary resuscitation: an underused lifesaving system. Eur J Emerg Med. 2007; 14:256–9.
26. Garza AG, Gratton MC, Chen JJ, Carlson B. The accuracy of predicting cardiac arrest by emergency medical services dispatchers: the calling party effect. Acad Emerg Med 2003; 10:955–960.
27. Kuisma M, Boyd J, Vayrynen T, Repo J, Nousila-Wiik M, Holmstrom P. Emergency call processing and survival from out-of-hospital ventricular fibrillation. Resuscitation 2005; 67:89–93.
28. Nurmi J, Pettila V, Biber B, Kuisma M, Komulainen R, Castren M. Effect of protocol compliance to cardiac arrest identification by emergency medical dispatchers. Resuscitation 2006; 70:463–469.
29. Attard Biancardi M., Spiteri P., Pace M.P. Cardiac arrest recognition and telephone CPR by emergency medical dispatchers. Malta Medical School Gazette 2017; volume1 issue 1.
30. Resuscitation academy. ‘English TCPR instructions’ available at: http://www.resuscitationacademy.org
31. Maltese population as at 2019 available at: https://www.worldometers.info/world-population/malta-popultion/
32. Formosa S.; Sandra Scicluna; Jacqueline Azzopardi, eds. (January 2013). Realities of Crime, Society and Landuse in the Mediterranean: JANUS I(PDF). Msida: Department of Criminology, University of Malta. p. 59-60. doi:13140/2.1.1230.4322. ISBN 978-99957-834-0-2.
33. Liu S, Vaillancourt C, Kasaboski A, Taljaard M. Bystander fatigue and CPR quality by older bystanders: a randomized crossover trial comparing continuous chest compressions and 30:2 compressions to ventilations. CJEM 2016; 18:461–8. https://doi.org/10.1017/cem.2016.373 PMID: 27650514
34. Cabrini L., G. Biondi-Zoccai, G. Landoni, M. Greco, F. Vinciguerra, T. Greco et al. Bystander-initiated chest compression only CPR is better than standard CPR in out-of-hospital cardiac arrest. HSR Proceedings in Intensive Care and Cardiovascular Anesthesia 2010; 2: 279-285
35. SOS-KANTO study group. Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study. Lancet 2007; 369: 920-926.
36. Bohm K, Rosenqvist M, Herlitz J, Hollenberg J, Svensson L. Survival is similar after standard treatment and chest compression only in out-of-hospital bystander cardiopulmonary resuscitation. Circulation 2007; 116: 2908-2912.
37. Iwami T, Kawamura T, Hiraide A, Berg RA, Hayashi Y, Nishiuchi T et al. Effectiveness of bystander-initiated cardiac-only resuscitation for patients with out-of-hospital cardiac arrest. Circulation 2007; 116: 2900-2907.
38. Riou M., Stephen Ball, Austin Whiteside, Janet Bray, Gavin D. Perkins, Karen Smith et al. ‘We’re going to do CPR’: A linguistic study of the words used to initiate dispatcher-assisted CPR and their association with caller agreement’. Resuscitation 133 (2018) 95–100
39. Park SO, Hong CK, Shin DH, Lee JH, Hwang SY. Efficacy of metronome sound guidance via a phone speaker during dispatcher-assisted compression-only cardiopulmonary resuscitation by an untrained layperson: a randomised controlled simulation study using a manikin. Emerg Med J 2013; 30:657–61.
40. Scott G, Barron T, Gardett I, Broadbent M, Downs H, Devey L, et al. Can a Software-Based Metronome Tool Enhance Compression Rate in a Realistic 911 Call Scenario Without Adversely Impacting Compression Depth for Dispatcher-Assisted CPR? Prehosp Disaster Med 2018; 33:399–405.
41. Wik L, Kramer-Johansen J, Myklebust H, Sørebø H, Svensson L, Fellows B et al. Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest. JAMA 2005; 293:299–304.
42. Kramer-Johansen J, Myklebust H, Wik L, Fellows B, Svensson L, Sørebø H et al. Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study. Resuscitation 2006; 71:283–292.
43. Brown TB, Dias JA, Saini D, Shah RC, Cofield SS, Terndrup TE et al. Relationship between knowledge of cardiopulmonary resuscitation guidelines and performance. Resuscitation 2006; 69:253–261.
44. Gutwirth H, Williams B, Boyle M. Rescuer fatigue in cardiopulmonary resuscitation: a review of the literature. JEPHC 2009; 7(4):19.
45. Bjørshol CA, Sunde K, Myklebust H, Assmus J, Søreide E. Decay in chest compression quality due to fatigue is rare during prolonged advanced life support in a manikin model. Scand J Trauma Resusc Emerg Med 2011; 19:46.
46. Russo SG, Peter N, Sylvia R, Arnd T, André N, Michael Q et al. Impact of physical fitness and biometric data on the quality of external chest compression: a randomised, crossover trial. BMC Emerg Med 2011; 11:20.
47. Hasegawa T., Rie Daikoku, Shin Saito, Yayoi Saito. Relationship between weight of rescuer and quality of chest compression during cardiopulmonary resuscitation. Journal of Physiological Anthropology 2014; 33:16 http://www.jphysiolanthropol.com/content/33/1/16
48. Chi CH, Tsou JY, Su FC. Effects of compression-to-ventilation ratio on compression force and rescuer fatigue during cardiopulmonary resuscitation. Am J Emerg Med 2010; 28:10161023.
49. Mirza M., Todd B. Brown, Devashish Saini, Tracy L Pepper, Hari Krishna Nandigam, Niroop Kaza, et al. Instructions to “push as hard as you can” improve average chest compression depth in dispatcher-assisted Cardiopulmonary Resuscitation. Resuscitation 2008; 79(1): 97–102.

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