title: The importance of appropriate concentrations of inspired carbon dioxide on induced hypothermia under halothane-ether azeotrope anesthesia.
abstract: Thirty adult mongrel dogs were divided into 3 equal groups and studied to define the optimal PCO2 level with azeotrope (halothane-diethyl ether) anesthesia under surface hypothermia (Groups I, II and III = F1CO2 0%, 5% and 10%, respectively). All animals were cooled to 18-20 degrees C and were subjected to 30 (Group I) or 60 minutes (Groups II and III) of total circulatory arrest. Group I animals had frequent arrhythmic episodes during cooling and postoperative motor disturbances occurred in 80% despite only 30 minutes of circulatory arrest. By contrast Group II animals were less arrhythmic during cooling; were easily resuscitated following 60 minutes of arrest and only 30% developed moderate reversible motor disturbances postoperatively. Hemodynamics were similar between Groups II and III during cooling but resuscitation using an F1CO2 of 10% (Group III) was extremely difficult and required massive cardiotonic support throughout rewarming. Furthermore, two dogs in Group III died within the first two postoperative days. However, none of the 8 survivors displayed neurological abnormalities. On balance, a ventilatory regimen utilizing 5% CO2 during surface-induced hypothermia under azeotrope anesthesia resulted in optimum intraoperative management and a satisfactory postoperative course and although some CNS disturbance (high-stepping gait) was noted, all animals recovered completely.
mesh_terms: D000136:Acid-Base Equilibrium; D000768:Anesthesia, General; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology; D002245:Carbon Dioxide / Q000008:administration & dosage*; D002493:Central Nervous System Diseases / Q000209:etiology; D004285:Dogs; D004986:Ether; D005019:Ethyl Ethers; D005260:Female; D006221:Halothane; D006439:Hemodynamics; D007036:Hypothermia, Induced; D007430:Intraoperative Care; D008297:Male; D011183:Postoperative Complications / Q000209:etiology; D012121:Respiration, Artificial; D013997:Time Factors
chemical_list: D005019:Ethyl Ethers; D004986:Ether; D002245:Carbon Dioxide; D006221:Halothane