"Bystander" chest compressions and assisted ventilation independently improve outcome from piglet asphyxial pulseless "cardiac arrest"

Background-Bystander cardiopulmonary resuscitation (CPR) without assisted v entilation may be as effective as CPR with assisted ventilation for ventric ular fibrillatory cardiac arrests. However, chest compressions alone or ven tilation alone is not effective for complete asphyxial cardiac arrests (los s of aortic pulsations). The objective of this investigation was to determi ne whether these techniques can independently improve outcome at an earlier stage of the asphyxial process. Methods and Results-After induction of anesthesia, 40 piglets (11.5+/-0.3 k g) underwent endotracheal tube damping (6.8+/-0.3 minutes) until simulated pulselessness, defined as aortic systolic pressure <50 mm Hg. For the 8-min ute "bystander CPR" period, animals were randomly assigned to chest compres sions and assisted ventilation (CC+V), chest compressions only (CC), assist ed ventilation only (V), or no bystander CPR (control group). Return of spo ntaneous circulation occurred during the first 2 minutes of bystander CPR i n 10 of 10 CC + V piglets, 6 of 10 V piglets, 4 of 10 CC piglets, and none of the controls (CC+V or V versus controls, P<0.01; CC+V versus CC and V co mbined, P=0.01). During the first minute of CPR, arterial and mixed venous blood gases were superior in the 3 experimental groups compared with the co ntrols. Twenty-four-hour survival was similarly superior in the 3 experimen tal groups compared with the controls (8 of 10, 6 of 10, 5 of 10, and 0 of 10, P<0.05 each). Conclusions-Bystander CPR with CC+V improves outcome in the early stages of apparent pulseless asphyxial cardiac arrest. In addition, this study estab lishes that bystander CPR with CC or V can independently improve outcome.