Resuscitation
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Recent studies have demonstrated that small (i.e., 2-5 degrees C) reductions in temperature may protect the brain and spinal cord from ischemic injury. The present study evaluated the physiologic response of anesthetized animals to convective-based cooling and warming. Six shaved, isoflurane-anesthetized (1.50% end-expired; 1 MAC), pancuronium-paralyzed dogs were subjected to temperature manipulation. ⋯ Whole body oxygen consumption and heart rate decreased in a temperature-dependent fashion. Cardiac rhythm disturbances were rare. The authors conclude that convection-based corporeal cooling and rewarming are efficacious methods for non-invasively and uniformly altering CNS temperatures without adversely affecting cerebral or systemic physiology.
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Measures of CO2 have been shown to correlate with coronary perfusion pressure and cardiac output during cardiac arrest. We evaluated arterial pH (pHa) relative to blood flow during cardiac arrest in a canine electromechanical dissociation (EMD) model of cardiac arrest using different resuscitation techniques. Following 15 min of cardiac arrest, 24 mongrel dogs received epinephrine with continued CPR or closed-chest cardiopulmonary bypass. ⋯ Eventual survivors (n = 15) had an early significant decrease in pHa, base excess and a significant increase in PaCO2 which was not present in non-survivors (n = 9). Neither pHa nor PaCO2 correlate with blood flow under low flow conditions of CPR. However, with effective circulatory assistance, pHa and PaCO2 reflect systemic blood flow and reperfusion washout.