15 Study Design

16 Reduced Quality Factors

17 0 = no serious, - = serious,

18 - - = very serious

19 Positive Quality Factors

20 0 = none, + = one, ++ = multiple

21 Dichotomous Outcome Summary

22 Non-Dichotomous Outcome Summary

23 Brief description

24 Overall Quality

25 High, moderate, low,
very low, none

26 No of studies

27 Study Type

28 RoB

29 Indirectness

30 Imprecision

31 Inconsistency

32 Large Effect

33 Dose-Response

34 Confounder

35 # Intervention with Outcome

36 # Control with Outcome

37 RR (95% CI)

38 Outcome: Surrogate markers of perfusion

39 4

40 EXP

41 0

42 - -

43 --

44 0

45 0

46 0

47 +

48 0

49 Various surrogate markers of perfusion are improved when shorter duty cycles and less fraction of time spent “leaning” on the chest occur.

50 Moderate

52 Introduction

53 Incomplete chest wall recoil during CPR may increase intrathoracic pressure between chest compressions and thereby decrease venous return. Leaning on the chest between compressions will impair chest wall recoil and has been found to occur commonly in human clinical studies. The current human and previous veterinary guidelines recommend allowing for complete chest wall recoil between compressions based primarily on experimental data. This question investigates whether impaired chest wall recoil affects outcome in dogs and cats undergoing CPR.

54 Consensus on science

55 For the most critical outcomes of favorable neurologic outcome, survival to discharge and ROSC, we identified no studies that address the PICO question.

56 Outcome 4: Surrogate markers of perfusion:

57 Four experimental studies (moderate level of evidence, downgraded for serious indirectness) in a porcine ventricular fibrillation model of cardiopulmonary arrest were identified, 2 of which document that leaning decreases cardiac index and left ventricular myocardial index.1,2 Two studies evaluated different duty cycles and documented decreased duty cycle or maximizing the recoil phase increased cerebral or myocardial perfusion pressure; we considered adequate time in non-compression to be important for left ventricular filling during the recoil phase.3,4 Cerebral perfusion pressure and aortic pressure were optimized by a 50:50 duty cycle of compression : non-compression in 8-week-old piglets.4

58 Treatment recommendations

59 We recommend allowing full chest wall recoil between chest compressions in dogs and cats undergoing CPR (strong recommendation, moderate quality of evidence).

60 We recommend targeting a duty cycle of 50:50 for compression : non-compression during CPR in dogs and cats (strong recommendation, moderate quality of evidence).

61 Justification of treatment recommendation

62 All pertinent evidence to date shows improved surrogate markers of perfusion when there is adequate opportunity for full chest wall recoil.

63 Knowledge gaps

64 Whether allowing full chest wall recoil during CPR in dogs and cats improves neurologic outcome, survival to discharge, or ROSC is unknown.

65 There is no supporting evidence to address the PICO question in human clinical trials, nor in dogs and cats in any setting.

66 Whether veterinary health care providers can maintain adequate chest compression technique without leaning between compressions for a full 2-minute BLS cycle during CPR in dogs and cats of variable size and conformations is unknown.

67 It is unclear whether health care providers are able to assess themselves and others for leaning during the recoil phase of CPR in dogs and cats.