Abdominal compressions during CPR: Hemodynamic effects of altering timing and force

To determine the optimal method of applying abdominal compressions during cardiopulmonary resuscitation (CPR), 3 levels of pressure (25, 50, and 100 torr) were applied to the abdomen a) continuously and b) as 500 msec pulses at 10 different phases during the CPR cycle in 8 anesthetized dogs. Thoracic aortic (Ao) and right atrial (RA) pressures were measured and P Ao − PR RA was calculated as the coronary perfusion gradient. A pneumatic piston device provided external chest compression (60/min, 120 lbs, for 50% of the cycle) and ventilation (80% 02, 12/min, at 20cm H 20). Another identical device provided abdominal compression (AC) via an air-filled bladder. High-pressure (100 torr) AC applied for 500 msec commencing 200 msec prior to chest compression demonstrated the best overall profile, raising mean aortic pressure 26 torr ( P < 0.001) and peak coronary perfusion gradient pressure 17 torn ( P < 0.02) from control values during standard CPR of 58 and 41 torr, respectively. We conclude that applying high-pressure, 500-msec pulses of AC 200 msec before chest compressions significantly improves CPR hemodynamics.