Three mechanical techniques of cardiopulmonary resuscitation in a canine model: 24-Hour survival and neurological outcome : Karl B. Kern, Alice B. Carpenter, Russell L. Showen, William D. Voorhees, Charles F. Babbs, Willis A. Tacker, Gordon A. Ewy. University of Arizona, Tucson, AZ 85721; Purdue University, West Lafayette, IN 47907

Abstract

We studied the effect of nifedipine, a calcium entry blocker, on the recovery of cerebral adenosine triphosphate (ATP), creatine phosphate (CP), and lactate levels following resuscitation from cardiac arrest. Using the cardiac arrest and resuscitation model of de Garavilla, Babbs, and Tacker with an arrest time of eight minutes, 76% of the animals arrested were resuscitated with an average intermittent abdominal compression-CPR time of 3.3 minutes. Rats were assigned randomly to the following groups: nonischemic; eight minutes of arrest without resuscitation; and postresuscitation treatment with either IV normal saline; 3 μg/kg nifedipine; 10 μg/kg nifedipine; or 30 μg/kg nifedipine. Treated animals were sacrificed at either 20 or 120 minutes thereafter. As expected, after eight minutes of cardiac arrest, the levels of ATP and CP dropped to near 0 and rebounded in all resuscitated animals. By 120 minutes after resuscitation, rats given the 10-μg/kg dose of nifedipine had levels of ATP equivalent to nonischemic values. Return of CP values to nonischemic levels was seen only at the 3-μg/kg dose and was independent of time of measurement. The ATP and CP levels in these nifedipine-treated groups were significantly better when compared to saline-treated controls. There were no treatment-dependent differences in lactate levels. We conclude that clinically appropriate doses of nifedipine had a beneficial effect on the recovery of cerebral high-energy phosphates after cardiac arrest and resuscitation.