TRANSCUTANEOUS PACING IN A HYPOTHERMIC-DOG MODEL

Study objective: To evaluate the hemodynamic response to transcutaneou s pacing (TCP) during rewarming from hypothermia. Methods: We conducte d a prospective, controlled laboratory investigation using 20 mongrel dogs. The animals were anesthetized, intubated, and mechanically venti lated. Arterial pressure, core temperature, and cardiac rhythm were co ntinuously monitored. All dogs were cooled to a core temperature of 27 degrees C; experimental animals were then subjected ro TCP with activ e rewarming, and control animals underwent sham trancutaneous pacing a nd rewarmed in the same manner. Serial hemodynamic measurements, time to rewarming, and cardiac isoenzyme concentrations were analyzed. Resu lts: Rewarming was accomplished significantly faster in the paced grou p (171.5+/-31.5 minutes) than in the control group (254+/-55.9 minutes , P<.05). After rewarming, the mean cardiac index in the paced dogs re turned to 84% of baseline, compared with 63% of baseline in the nonpac ed group (P<.05). None of the paced animals demonstrated significant h emodynamic deterioration, potentially lethal arrhythmias, or other evi dence of myocardial injury. Conclusion: TCP is safe, effective and eas ily implemented in dogs. In this small series of dogs, ICP restored an d maintained hemodynamic stability and allowed the hypothermic animals to rewarm in half the time required by their nonpaced counterparts.