Resuscitating hypothermic dogs after 2 hours of circulatory arrest below 6 degrees C

Ultraprofound hypothermia may have a place in trauma rescue and resuscitation. We describe resuscitation of dogs after asanguineous perfusion and circulatory arrest of 2 hours at 2 degrees to 4 degrees C. Nine dogs were cooled using a bypass apparatus and their circulating blood replaced with bicarbonated Hextend (Abbott, North Chicago, IL). Perfusion was continued to 2 degrees to 4 degrees C, and 60 mL of 2 mol/L KCl and 20 mL of 50% MgSO(4).7H(2)O were infused intra-arterially, and circulation was arrested for 2 hours. The dogs were then rewarmed, transfused, defibrillated, weaned from bypass, and allowed to awaken. Preoperative and postoperative biochemistry and hematology were compared. Six dogs recovered fully. One of these dogs died of an infection 2 weeks later. Three other dogs never recovered because of technical or procedural difficulties. Biochemical and hematologic parameters were normal by 3 weeks. Hypothermic blood substitution with Hextend allows resuscitation after 2 hours of ice-cold circulatory arrest in dogs.