Even four minutes of poor quality of CPR compromises outcome in a porcine model of prolonged cardiac arrest

Abstract

Objective: Untrained bystanders usually delivered suboptimal chest compression to victims who suffered from cardiac arrest in out-of-hospital settings. We therefore investigated the hemodynamics and resuscitation outcome of initial suboptimal quality of chest compressions compared to the optimal ones in a porcine model of cardiac arrest.

Methods: Fourteen Yorkshire pigs weighted 30 ± 2 kg were randomized into good and poor cardiopulmonary resuscitation (CPR) groups. Ventricular fibrillation was electrically induced and untreated for 6 mins. In good CPR group, animals received high quality manual chest compressions according to the Guidelines (25% of animal's anterior-posterior thoracic diameter) during first two minutes of CPR compared with poor (70% of the optimal depth) compressions. After that, a 120-J biphasic shock was delivered. If the animal did not acquire return of spontaneous circulation, another 2 mins of CPR and shock followed. Four minutes later, both groups received optimal CPR until total 10 mins of CPR has been finished.

Results: All seven animals in good CPR group were resuscitated compared with only two in poor CPR group (P < 0.05). The delayed optimal compressions which followed 4 mins of suboptimal compressions failed to increase the lower coronary perfusion pressure of five non-survival animals in poor CPR group.

Conclusions: In a porcine model of prolonged cardiac arrest, even four minutes of initial poor quality of CPR compromises the hemodynamics and survival outcome.

Figure 1

Comparison of compression depth values between the two groups during initial 2 mins of cardiopulmonary resuscitation. *P < 0.05. PC = chest compression.

Figure 2

Comparison of coronary perfusion pressure (CPP) values between the two groups during initial 2 mins of cardiopulmonary resuscitation. *P < 0.05. PC = chest compression.

Figure 3

The characteristics of compression depth and coronary perfusion pressure (CPP) in poor CPR group during the entire 10 mins of cardiopulmonary resuscitation procedure. PC = chest compression.