Resuscitation 85 (2014) 153–154
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Editorial
Press hard – But perhaps not too hard
Since the description of cardiopulmonary resuscitation by Koewenhoven, Jude, and Knickerbocker in 1960, the recommended depth for chest compression has remained at 40–50 mm.1 These figures were extrapolated from studies on dogs, but subsequent human studies have been, and still are, few and far between. Over the years, several animal models have suggested that deeper compressions might improve outcome, but it was not until 2010 that the International Liaison Committee on Resuscitation (ILCOR) considered the evidence strong enough to recommend a change.2 Four studies, in particular, led to this decision: a mathematical analysis of download data from automated external defibrillators,3 and 3 studies of data from adult cardiac arrests,4–6 all of which indicated that outcome would be improved if chest compression was increased beyond a depth of 50 mm. The 2010 ILCOR conclusion was: ‘Human studies suggest that compressions of 5 cm or more may improve success of defibrillation and ROSC. . .’ The ultimate reason for making changes to the guidelines is to improve outcome from cardiac arrest. So has this modest change in chest compression depth had any effect? In 2012, a positive association between depth of compression and survival was supported by a prospective study of out-ofhospital cardiac arrests by the Resuscitation Outcomes Consortium (ROC) Investigators in the US.7 This showed improvement in return of spontaneous circulation (ROSC) and survival to hospital discharge as chest compression depth increased, but there was no clear benefit from compressing deeper than 50 mm. A new study, by Vadeboncoeur and colleagues from Arizona, published in this issue of Resuscitation,8 now supports a compression depth of 50 mm or more. The authors looked at the outcome from out-of-hospital cardiac arrest before and after EMS personnel had received 4 h of training in accordance with the 2010 criteria for chest compression, and had been provided with real-time audiovisual feedback via their defibrillators. The mean depth of compression was significantly deeper in survivors (53.6 mm, 95% CI: 50.5–56.7) than non-survivors (48.8 mm, 95% CI: 47.6–50.0). Allowing for other variables, the authors calculated that the odds of survival and a favourable neurological outcome increased by 1.29 and 1.30 respectively for each additional 5 mm in compression depth. Expressed another way, the odds of achieving each of these favourable outcomes improved by 1.21 for every 10% increase in the number of compressions exceeding 50 mm depth. There are, as the authors freely admit, some limitations in the study. In particular, the EMS personnel used a protocol of an initial series of 200 uninterrupted chest compressions, a single
0300-9572/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2013.11.016
shock (if indicated), and 200 further chest compressions before a pulse check, rhythm reanalysis, administration of epinephrine, or endotracheal intubation – so-called minimally interrupted cardiac resuscitation (MICR). Nevertheless, this study does reinforce previous evidence that a compression depth greater than 50 mm can lead to better survival. In 2010, ILCOR also concluded: ‘. . .there is insufficient evidence to recommend a specific upper limit for chest compression depth’. Clearly there must be an upper limit to the depth that is both safe and effective, but are we any nearer to knowing what this is? The maximum compression depth reported in the Vadeboncoeur study was about 60 mm. Is there a downside to this? The mean force required to produce a compression depth of 40 mm (the previous guideline minimum) on an adult has been shown to be approximately 30 kg, and a 50 kg force is needed to ensure this depth is achieved in 95% of cases.9 Extrapolation of these figures suggests that a force of around 80 kg would be needed to reach a compression depth of 60 mm. Is this feasible? We only have evidence gathered before the 2010 guidelines, but when volunteers performed simulated chest compressions on bathroom scales, 40% of trained rescuers and 63% of lay rescuers failed to produce a compression force above 56 kg.10 A significant increase in effort will have to be made by most rescuers if 60 mm compressions are to be achieved, let alone any deeper compressions. Are there risks associated with deeper chest compression? It has been recognised for some time that rib and sternal fractures are relatively common during CPR, although rarely has serious internal injury been reported. A study of survivors of cardiac arrest, carried out before the current guidelines were published, reported incidences of 65% rib fractures and 30% sternal fractures. Six out of 40 of the patients had fracture-related complications including pneumothorax, subclavian vein injury, and chest wall hematomata.11 That the rate of complications might rise when deeper compressions are given has been raised in a short report, which notes a 3-fold rise in significant chest wall injuries and prolonged stays in the intensive care unit subsequent to the introduction of the 2010 guidelines.12 This concern has now been supported by a more recent study showing an association between chest wall injuries and depth of compression, particularly when this exceeds 60 mm.13 The accumulating evidence, therefore, seems to support an outcome benefit from chest compression of at least 50 mm, but the effort needed to increase this above 60 mm, together with the risk
154
Editorial / Resuscitation 85 (2014) 153–154
of chest wall damage, suggests that 60 mm should be considered the upper limit. When it came to translating the 2010 ILCOR recommendations into guidelines the American Heart Association followed the ILCOR advice to the letter with ‘a compression depth of at least 2 in./5 cm’.14 The European Resuscitation Council, on the other hand, considered that an upper limit needed to be specified, and chose to advise ‘at least 5 cm (but not exceeding 6 cm)’15 – current evidence supports the ERC’s decision. Conflicts of interest None. References 1. Jude JR, Kouwenhoven WB, Knickerbocker GG. A new approach to cardiac resuscitation. Ann Surg 1961;154:311–7. 2. Koster RW, Sayre MR, Botha M, et al. International consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Part 5. Adult basic life support. Resuscitation 2010;81S:e48–70. 3. Babbs CF, Kemeny AE, Quan W, Freeman G. A new paradigm for human resuscitation research using intelligent devices. Resuscitation 2008;77:306–15. 4. Edelson DA, Abella BS, Kramer-Johansen J, et al. Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest. Resuscitation 2006;71:137–45. 5. Kramer-Johansen J, Myklebust H, Wik L, et al. Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study. Resuscitation 2006;71:283–92. 6. Edelson DP, Litzinger B, Arora V, et al. Improving in-hospital cardiac arrest process and outcomes with performance debriefing. Arch Intern Med 2008;168:1063–9.
7. Steill IG, Brown SP, Christenson J, et al. What is the role of chest compression depth during out-of-hospital cardiac arrest resuscitation? Crit Care Med 2012;40:1192–8. 8. Vadeboncoeur T, Stolz U, Panchal A, et al. Chest compression depth and survival in out-of-hospital cardiac arrest. Resuscitation 2013;85:182–8. 9. Tomlinson AE, Nysaetherc J, Kramer-Johansen J, Steen PA, Dorph E. Compression force-depth relationship during out-of-hospital cardiopulmonary resuscitation. Resuscitation 2007;72:364–70. 10. Geddes LA, Boland MK, Taleyarkhan PR, Vitter J. Chest compression force of trained and untrained CPR rescuers. Cardiovasc Eng 2007;7:47–50. 11. Kim EY, Yang HJ, Sung YM, et al. Multidetector CT findings of skeletal chest injuries secondary to cardiopulmonary resuscitation. Resuscitation 2011;82:1285–8. 12. Young N, Cook B, Gillies M. New resuscitation guidelines may result in an increased incidence of severe chest wall injury, and lead to prolonged length of stay in the intensive care unit. Resuscitation 2011;82:1355. 13. Hellevuo H, Sainio M, Nevalainen R, et al. Deeper chest compression – more complications for cardiac arrest patients. Resuscitation 2013;84: 760–5. 14. Berg RA, Hemphill R, Abella BS, et al. Part 5: adult basic life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2010;122:S685– 705. 15. Koster RW, Baubin MA, Bossaert LL, et al. European Resuscitation Council Guidelines for resuscitation 2010. Section 2. Adult basic life support and use of automated external defibrillators. Resuscitation 2010;81:1277–92.
Anthony J. Handley Honorary Consultant Physician & Cardiologist, Colchester General Hospital, United Kingdom E-mail address: [email protected] 16 November 2013
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Editorial
Press hard – But perhaps not too hard
Since the description of cardiopulmonary resuscitation by Koewenhoven, Jude, and Knickerbocker in 1960, the recommended depth for chest compression has remained at 40–50 mm.1 These figures were extrapolated from studies on dogs, but subsequent human studies have been, and still are, few and far between. Over the years, several animal models have suggested that deeper compressions might improve outcome, but it was not until 2010 that the International Liaison Committee on Resuscitation (ILCOR) considered the evidence strong enough to recommend a change.2 Four studies, in particular, led to this decision: a mathematical analysis of download data from automated external defibrillators,3 and 3 studies of data from adult cardiac arrests,4–6 all of which indicated that outcome would be improved if chest compression was increased beyond a depth of 50 mm. The 2010 ILCOR conclusion was: ‘Human studies suggest that compressions of 5 cm or more may improve success of defibrillation and ROSC. . .’ The ultimate reason for making changes to the guidelines is to improve outcome from cardiac arrest. So has this modest change in chest compression depth had any effect? In 2012, a positive association between depth of compression and survival was supported by a prospective study of out-ofhospital cardiac arrests by the Resuscitation Outcomes Consortium (ROC) Investigators in the US.7 This showed improvement in return of spontaneous circulation (ROSC) and survival to hospital discharge as chest compression depth increased, but there was no clear benefit from compressing deeper than 50 mm. A new study, by Vadeboncoeur and colleagues from Arizona, published in this issue of Resuscitation,8 now supports a compression depth of 50 mm or more. The authors looked at the outcome from out-of-hospital cardiac arrest before and after EMS personnel had received 4 h of training in accordance with the 2010 criteria for chest compression, and had been provided with real-time audiovisual feedback via their defibrillators. The mean depth of compression was significantly deeper in survivors (53.6 mm, 95% CI: 50.5–56.7) than non-survivors (48.8 mm, 95% CI: 47.6–50.0). Allowing for other variables, the authors calculated that the odds of survival and a favourable neurological outcome increased by 1.29 and 1.30 respectively for each additional 5 mm in compression depth. Expressed another way, the odds of achieving each of these favourable outcomes improved by 1.21 for every 10% increase in the number of compressions exceeding 50 mm depth. There are, as the authors freely admit, some limitations in the study. In particular, the EMS personnel used a protocol of an initial series of 200 uninterrupted chest compressions, a single
0300-9572/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2013.11.016
shock (if indicated), and 200 further chest compressions before a pulse check, rhythm reanalysis, administration of epinephrine, or endotracheal intubation – so-called minimally interrupted cardiac resuscitation (MICR). Nevertheless, this study does reinforce previous evidence that a compression depth greater than 50 mm can lead to better survival. In 2010, ILCOR also concluded: ‘. . .there is insufficient evidence to recommend a specific upper limit for chest compression depth’. Clearly there must be an upper limit to the depth that is both safe and effective, but are we any nearer to knowing what this is? The maximum compression depth reported in the Vadeboncoeur study was about 60 mm. Is there a downside to this? The mean force required to produce a compression depth of 40 mm (the previous guideline minimum) on an adult has been shown to be approximately 30 kg, and a 50 kg force is needed to ensure this depth is achieved in 95% of cases.9 Extrapolation of these figures suggests that a force of around 80 kg would be needed to reach a compression depth of 60 mm. Is this feasible? We only have evidence gathered before the 2010 guidelines, but when volunteers performed simulated chest compressions on bathroom scales, 40% of trained rescuers and 63% of lay rescuers failed to produce a compression force above 56 kg.10 A significant increase in effort will have to be made by most rescuers if 60 mm compressions are to be achieved, let alone any deeper compressions. Are there risks associated with deeper chest compression? It has been recognised for some time that rib and sternal fractures are relatively common during CPR, although rarely has serious internal injury been reported. A study of survivors of cardiac arrest, carried out before the current guidelines were published, reported incidences of 65% rib fractures and 30% sternal fractures. Six out of 40 of the patients had fracture-related complications including pneumothorax, subclavian vein injury, and chest wall hematomata.11 That the rate of complications might rise when deeper compressions are given has been raised in a short report, which notes a 3-fold rise in significant chest wall injuries and prolonged stays in the intensive care unit subsequent to the introduction of the 2010 guidelines.12 This concern has now been supported by a more recent study showing an association between chest wall injuries and depth of compression, particularly when this exceeds 60 mm.13 The accumulating evidence, therefore, seems to support an outcome benefit from chest compression of at least 50 mm, but the effort needed to increase this above 60 mm, together with the risk
154
Editorial / Resuscitation 85 (2014) 153–154
of chest wall damage, suggests that 60 mm should be considered the upper limit. When it came to translating the 2010 ILCOR recommendations into guidelines the American Heart Association followed the ILCOR advice to the letter with ‘a compression depth of at least 2 in./5 cm’.14 The European Resuscitation Council, on the other hand, considered that an upper limit needed to be specified, and chose to advise ‘at least 5 cm (but not exceeding 6 cm)’15 – current evidence supports the ERC’s decision. Conflicts of interest None. References 1. Jude JR, Kouwenhoven WB, Knickerbocker GG. A new approach to cardiac resuscitation. Ann Surg 1961;154:311–7. 2. Koster RW, Sayre MR, Botha M, et al. International consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Part 5. Adult basic life support. Resuscitation 2010;81S:e48–70. 3. Babbs CF, Kemeny AE, Quan W, Freeman G. A new paradigm for human resuscitation research using intelligent devices. Resuscitation 2008;77:306–15. 4. Edelson DA, Abella BS, Kramer-Johansen J, et al. Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest. Resuscitation 2006;71:137–45. 5. Kramer-Johansen J, Myklebust H, Wik L, et al. Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study. Resuscitation 2006;71:283–92. 6. Edelson DP, Litzinger B, Arora V, et al. Improving in-hospital cardiac arrest process and outcomes with performance debriefing. Arch Intern Med 2008;168:1063–9.
7. Steill IG, Brown SP, Christenson J, et al. What is the role of chest compression depth during out-of-hospital cardiac arrest resuscitation? Crit Care Med 2012;40:1192–8. 8. Vadeboncoeur T, Stolz U, Panchal A, et al. Chest compression depth and survival in out-of-hospital cardiac arrest. Resuscitation 2013;85:182–8. 9. Tomlinson AE, Nysaetherc J, Kramer-Johansen J, Steen PA, Dorph E. Compression force-depth relationship during out-of-hospital cardiopulmonary resuscitation. Resuscitation 2007;72:364–70. 10. Geddes LA, Boland MK, Taleyarkhan PR, Vitter J. Chest compression force of trained and untrained CPR rescuers. Cardiovasc Eng 2007;7:47–50. 11. Kim EY, Yang HJ, Sung YM, et al. Multidetector CT findings of skeletal chest injuries secondary to cardiopulmonary resuscitation. Resuscitation 2011;82:1285–8. 12. Young N, Cook B, Gillies M. New resuscitation guidelines may result in an increased incidence of severe chest wall injury, and lead to prolonged length of stay in the intensive care unit. Resuscitation 2011;82:1355. 13. Hellevuo H, Sainio M, Nevalainen R, et al. Deeper chest compression – more complications for cardiac arrest patients. Resuscitation 2013;84: 760–5. 14. Berg RA, Hemphill R, Abella BS, et al. Part 5: adult basic life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2010;122:S685– 705. 15. Koster RW, Baubin MA, Bossaert LL, et al. European Resuscitation Council Guidelines for resuscitation 2010. Section 2. Adult basic life support and use of automated external defibrillators. Resuscitation 2010;81:1277–92.
Anthony J. Handley Honorary Consultant Physician & Cardiologist, Colchester General Hospital, United Kingdom E-mail address: [email protected] 16 November 2013
