RECOVER 2.0 Worksheet

QUESTION ID: BLS-10

PICO Question:
In non-intubated cats and dogs in CPA or during single-rescuer CPR in cats and dogs (P), does chest compression only CPR (I) when compared to conventional CPR (C) improve ... (O)?

Outcomes:
Favorable neurologic outcome, PaCO2, Oxygenation, Surrogate marker(s) of perfusion, Survival to discharge, ROSC

Prioritized Outcomes (1= most critical; final number = least important):

1. Favorable neurologic outcome
2. Survival to discharge
3. PaCO2
4. Oxygenation
5. ROSC
6. Surrogate markers of perfusion

Domain chairs: Steve Epstein, Kate Hopper; final edits by Jamie Burkitt

Evidence evaluators: Andrew Landerville, Casey Kohen

Conflicts of interest: None reported

Search strategy: See attached document

Evidence Review:

Study Design		Reduced Quality Factors 0 = no serious, - = serious, - - = very serious				Positive Quality Factors 0 = none, + = one, ++ = multiple			Dichotomous Outcome Summary			Non-Dichotomous Outcome Summary Brief description	Overall Quality High, moderate, low, very low, none
No of studies	Study Type	RoB	Indirectness	Imprecision	Inconsistency	Large Effect	Dose-Response	Confounder	# Intervention with Outcome	# Control with Outcome	RR (95% CI)
Outcome: Favorable neurologic outcome
1	CT	0	- -	0	0	0	0	0					Low
10	EX	-	-	0	-	0	0	0					Very low
17	OBS	-	- -	0	-	0	0	0					Very low
Outcome: Survival to discharge
3	CT	0	- -	0	0	0	0	0					Low
5	OBS	0	- -	0	-	0	0	0					Very low
Outcome: PaCO2
15	EX	-	- -	- -	0	+	0	0					Very low

Outcome: Oxygenation
14	EX	-	- -	- -	0	+	0	0					Very low

PICO Question Summary

Introduction

Chest compressions are recognized as an essential component of BLS. When relying on lay persons for CPR, there is some debate about whether it is preferable to focus on chest compressions only (no ventilation) to make it easier to teach, remember, and perform. However, there is concern that compression-only CPR may be less effective because of inadequate oxygenation and ventilation. Ventilation during CPR is considered to have particular importance in asphyxial cardiac arrests, which are believed to be the most common type of CPA in dogs and cats. The current human guidelines for adults with OHCA recommend chest compressions be performed for all patients and suggest that rescue breaths be provided if the rescuer is trained and willing.[ref] In human infants and children in whom the cause of CPA is most likely to be asphyxial in nature, there is more emphasis on ventilation during CPR, and current guidelines recommend CPR with chest compressions and rescue breaths for this population.1

Consensus on science

Outcome 1: Favorable neurologic outcome: For the most critical outcome of FNO, we identified 28 studies including 1 clinical trial in adult human beings (low quality of evidence, downgraded for very serious indirectness),2 10 experimental swine trials (very low quality of evidence, downgraded for serious risk of bias, serious indirectness, and serious inconsistency) 3–12, and 17 observational studies in people (very low quality of evidence, downgraded for serious risk of bias, very serious indirectness, and serious inconsistency) 12–29 that address the PICO question. One randomized, multicenter clinical trial of adults with OHCA receiving dispatcher-instructed bystander CPR found no difference in FNO between compression only CPR and conventional CPR.2Four experimental swine studies, 2 of which were asphyxial arrest models, found that conventional CPR was superior for FNO 3,5,7,9, whereas 6 experimental swine studies found no difference between compression only CPR and conventional CPR. 5,6,8,10–12 Five observational studies in people found conventional CPR was associated with a better neurologic outcome18,19,22,24,29 when compared to compression only CPR; however, 12 human clinical observational studies showed no difference in this outcome with compression-only CPR versus conventional CPR.13–17,20,21,23,25–28 Outcome 2: Survival to discharge: For the next critical outcome of survival to discharge, we identified 3 clinical trials (low quality of evidence, downgraded for very serious indirectness)2,30,31 and 5 observational studies (very low quality of evidence, downgraded for very serious indirectness and serious inconsistency)16,22–24,27 that address the PICO question. Three randomized human clinical trials found no difference in survival between compression-only and conventional CPR.2,30,31 Four human clinical observational studies found no difference in survival to discharge with compression-only CPR compared to conventional CPR. 16,22,23,27 However, one study in people with OHCA found compression-only CPR to be superior to standard for survival to hospital discharge.24 Outcome 3: PaCO2: For the important outcome of PaCO2, we identified 15 experimental animal trials addressing the PICO question (very low quality of evidence, downgraded for very serious risk of bias, very serious risk of indirectness, and serious imprecision, and upgraded for large effect). 3–7,9–11,32–38 Thirteen experimental swine studies found PaCO2 to be significantly higher with compression only CPR when compared to conventional CPR. 3–7,9,11,32–35,37 Two experimental animal studies (one dog, one swine) found no difference in PaCO2 between CPR types. 36,38 Outcome 4: Oxygenation: For the important outcome of oxygenation, we identified 14 experimental studies (very low quality of evidence, downgraded for serious risk of bias, very serious indirectness, and very serious imprecision, and upgraded for large effect) that address the PICO question. 3–7,9–11,32–36,38 Thirteen experimental animal studies (12 in swine, 1 in dogs) found oxygenation to be significantly decreased with compression-only CPR when compared to conventional CPR. 3–7,9–11,32–36,38 One swine study found no difference in oxygenation between CPR types.11 The outcomes of ROSC and Surrogate markers of perfusion were not evaluated since a recommendation could be made based on these 4 more critical outcomes.

Treatment recommendation

In non-intubated dogs and cats undergoing CPR or during single-rescuer CPR, we recommend provision of rescue breaths (strong recommendation, very low quality of evidence). In non-intubated dogs and cats undergoing CPR or during single-rescuer CPR including rescue breaths, we recommend provision of these rescue breaths via the mouth-to-nose (mouth-to-snout) technique (strong recommendation, expert opinion).

Justification of treatment recommendation

The recommendation for provision of rescue breaths to non-intubated dogs and cats undergoing CPR is based on the evidence that compression-only CPR was generally found to be inferior or equivalent to conventional CPR for the critical outcomes of FNO and survival. Because most CPA in cats and dogs is asphyxial (non-cardiac) in nature, rescue breathing during CPR may have greater importance in these animals than it does in most experimental and human clinical populations, in which cardiac causes of CPA predominate. Thus, we also based the decision to recommend rescue breaths in our non-intubated populations on the convincing evidence (large treatment effect) of improved PaCO2 and oxygenation seen in experimental studies of CPR when rescue breaths are delivered during CPR.

Knowledge gaps

Direct comparisons of compression-only CPR to conventional CPR in cats and dogs is lacking for the most critical outcomes of FNO and survival. As the predominant cause of CPA is different in human medicine, there is limited translational relevance of human clinical trials to veterinary medicine, and future veterinary clinical trials are needed. The efficacy of rescue breathing in non-intubated cats and dogs as well as the pause in chest compressions associated with rescue breathing have not been fully evaluated. The ability and willingness of lay persons to perform CPR with rescue breathing in animals is unknown.

References

1. Wyckoff MH, Greif R, Morley PT, et al. 2022 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces. Circulation. 2022;146(25).

2. Rea TD, Fahrenbruch C, Culley L, et al. CPR with chest compression alone or with rescue breathing. N Engl J Med. 2010;363(5):423-433.

3. Berg RA, Kern KB, Sanders AB, et al. Bystander cardiopulmonary resuscitation: Is ventilation necessary? Circulation. 1993;88(4):1907-1915.

4. Berg RA, Kern KB, Hilwig RW, Ewy GA. Assisted ventilation during “bystander” CPR in a swine acute myocardial infarction model does not improve outcome. Circulation. 1997;96(12):4364-4371.

5. Berg RA, Kern KB, Hilwig RW, et al. Assisted ventilation does not improve outcome in a porcine model of single-rescuer bystander cardiopulmonary resuscitation. Circulation. 1997;95(6):1635-1641.

6. Kern KB, Hilwig RW, Berg RA, Ewy GA. Efficacy of chest compression-only BLS CPR in the presence of an occluded airway. Resuscitation. 1998;39(3):179-188.

7. Berg RA, Hilwig RW, Kern KB, Babar I, Ewy GA. Simulated mouth-to-mouth ventilation and chest compressions (bystander cardiopulmonary resuscitation) improves outcome in a swine model of prehospital pediatric asphyxial cardiac arrest. Crit Care Med. 1999;27(9):1893-1899.

8. Berg RA, Hilwig RW, Kern KB, Ewy GA. “Bystander” chest compressions and assisted ventilation independently improve outcome from piglet asphyxial pulseless “cardiac arrest.” Circulation. 2000;101(14):1743-1748.

9. Sanders AB, Kern KB, Berg RA, et al. Survival and neurologic outcome after cardiopulmonary resuscitation with four different chest compression-ventilation ratios. Ann Emerg Med. 2002;40(6):553-562.

10. Ewy GA, Hilwig RW, Zuercher M, et al. Continuous chest compression resuscitation in arrested swine with upper airway inspiratory obstruction. Resuscitation. 2010;81(5):585-590.

11. Wang S, Li C, Ji X, et al. Effect of continuous compressions and 30:2 cardiopulmonary resuscitation on global ventilation/perfusion values during resuscitation in a porcine model. Crit Care Med. 2010;38(10):2024-2030.

12. Kim YW, Kim HI, Hwang SO, et al. Single Ventilation during Cardiopulmonary Resuscitation Results in Better Neurological Outcomes in a Porcine Model of Cardiac Arrest. Yonsei Med J. 2018;59(10):1232-1239.

13. Fukuda T, Fukuda-Ohashi N, Doi K, Matsubara T, Yahagi N. Effective pre-hospital care for out-of-hospital cardiac arrest caused by respiratory disease. Heart Lung Circ. 2015;24(3):241-249.

14. Maeda T, Kamikura T, Tanaka Y, et al. Impact of bystander-performed ventilation on functional outcomes after cardiac arrest and factors associated with ventilation-only cardiopulmonary resuscitation: A large observational study. Resuscitation. 2015;91:122-130.

15. Takei Y, Kamikura T, Nishi T, et al. Recruitments of trained citizen volunteering for conventional cardiopulmonary resuscitation are necessary to improve the outcome after out-of-hospital cardiac arrests in remote time-distance area: A nationwide population-based study. Resuscitation. 2016;105:100-108.

16. Naim MY, Burke RV, McNally BF, et al. Association of Bystander Cardiopulmonary Resuscitation With Overall and Neurologically Favorable Survival After Pediatric Out-of-Hospital Cardiac Arrest in the United States: A Report From the Cardiac Arrest Registry to Enhance Survival Surveillance Registry. JAMA Pediatr. 2017;171(2):133-141.

17. Fukuda T, Ohashi-Fukuda N, Kobayashi H, et al. Conventional Versus Compression-Only Versus No-Bystander Cardiopulmonary Resuscitation for Pediatric Out-of-Hospital Cardiac Arrest. Circulation. 2016;134(25):2060-2070.

18. Kaneko H, Hara M, Mizutani K, et al. Improving Outcomes of Witnessed Out-of-Hospital Cardiac Arrest After Implementation of International Liaison Committee on Resuscitation 2010 Consensus: A Nationwide Prospective Observational Population-Based Study. J Am Heart Assoc. 2017;6(8):e004959.

19. Goto Y, Funada A, Goto Y. Conventional versus chest-compression-only cardiopulmonary resuscitation by bystanders for children with out-of-hospital cardiac arrest. Resuscitation. 2018;122:126-134.

20. Zhang X, Zhang W, Wang C, et al. Chest-compression-only versus conventional cardiopulmonary resuscitation by bystanders for children with out-of-hospital cardiac arrest: A systematic review and meta-analysis. Resuscitation. 2019;134:81-90.

21. Fukuda T, Ohashi-Fukuda N, Hayashida K, Kondo Y, Kukita I. Bystander-initiated conventional vs compression-only cardiopulmonary resuscitation and outcomes after out-of-hospital cardiac arrest due to drowning. Resuscitation. 2019;145:166-174.

22. Tobin JM, Ramos WD, Greenshields J, et al. Outcome of Conventional Bystander Cardiopulmonary Resuscitation in Cardiac Arrest Following Drowning. Prehosp Disaster Med. Published online 2020:1-7.

23. Olasveengen TM, Wik L, Steen PA. Standard basic life support vs. continuous chest compressions only in out-of-hospital cardiac arrest. Acta Anaesthesiol Scand. 2008;52(7):914-919.

24. Bobrow BJ, Spaite DW, Berg RA, et al. Chest compression-only CPR by lay rescuers and survival from out-of-hospital cardiac arrest. JAMA. 2010;304(13):1447-1454.

25. Iwami T, Kawamura T, Hiraide A, et al. Effectiveness of bystander-initiated cardiac-only resuscitation for patients with out-of-hospital cardiac arrest. Circulation. 2007;116(25):2900-2907.

26. SOS-KANTO study group. Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study. Lancet. 2007;369(9565):920-926.

27. Ong MEH, Ng FSP, Anushia P, et al. Comparison of chest compression only and standard cardiopulmonary resuscitation for out-of-hospital cardiac arrest in Singapore. Resuscitation. 2008;78(2):119-126.

28. Goto Y, Maeda T, Goto Y. Impact of dispatcher-assisted bystander cardiopulmonary resuscitation on neurological outcomes in children with out-of-hospital cardiac arrests: a prospective, nationwide, population-based cohort study. J Am Heart Assoc. 2014;3(3):e000499.

29. Iwami T, Kitamura T, Kiyohara K, Kawamura T. Dissemination of Chest Compression-Only Cardiopulmonary Resuscitation and Survival After Out-of-Hospital Cardiac Arrest. Circulation. 2015;132(5):415-422.

30. Svensson L, Bohm K, Castrèn M, et al. Compression-only CPR or standard CPR in out-of-hospital cardiac arrest. N Engl J Med. 2010;363(5):434-442.

31. Hallstrom A, Cobb L, Johnson E, Copass M. Cardiopulmonary resuscitation by chest compression alone or with mouth-to-mouth ventilation. N Engl J Med. 2000;342(21):1546-1553.

32. Dorph E, Wik L, Strømme TA, Eriksen M, Steen PA. Oxygen delivery and return of spontaneous circulation with ventilation: Compression ratio 2:30 versus chest compressions only CPR in pigs. Resuscitation. 2004;60(3):309-318.

33. Cavus E, Meybohm P, Bein B, et al. Impact of different compression-ventilation ratios during basic life support cardiopulmonary resuscitation. Resuscitation. 2008;79(1):118-124.

34. Markstaller K, Rudolph A, Karmrodt J, et al. Effect of chest compressions only during experimental basic life support on alveolar collapse and recruitment. Resuscitation. 2008;79(1):125-132.

35. Kill C, Torossian A, Freisburger C, et al. Basic life support with four different compression/ventilation ratios in a pig model: The need for ventilation. Resuscitation. 2009;80(9):1060-1065.

36. Botran M, Lopez-Herce J, Urbano J, et al. Chest compressions versus ventilation plus chest compressions: A randomized trial in a pediatric asphyxial cardiac arrest animal model. Intensive Care Med. 2011;37(11):1873-1880.

37. Xanthos T, Karatzas T, Stroumpoulis K, et al. Continuous chest compressions improve survival and neurologic outcome in a swine model of prolonged ventricular fibrillation. Am J Emerg Med. 2012;30(8):1389-1394.

38. Hopper K, Rezende ML, Borchers A, Epstein SE. Efficacy of Manual Ventilation Techniques During Cardiopulmonary Resuscitation in Dogs. Front Vet Sci. 2018;5:239.

Supporting information:

Favorable neurologic outcome:

Clinical trial (1): One human clinical trial of compression only found no difference in neurologic outcome between compression only CPR and conventional CPR

Experimental (10): 4 studies found conventional CPR was superior for this outcome, 6 studies found no difference

Observational (17): 5 studies found conventional CPR was associated with a better neurological outcome, 12 studies showed no difference in this outcome

Survival to discharge:

Clinical trial (3): All 3 trials found no difference between compression only and conventional CPR

Observational (5): Four human clinical observational studies found no difference in survival to discharge with compression only CPR compared to conventional CPR. One study found compression only CPR to be superior for this outcome

PaCO2:

Experimental (15): 13 experimental animal studies found PaCO2 to be significantly higher with compression only CPR when compared to conventional CPR. Two studies found no difference in PaCO2 between CPR types

Oxygenation:

Experimental (14): 13 experimental animal studies found oxygenation to be significantly decreased with compression only CPR when compared with conventional CPR. One study found no difference in oxygenation.