398 PHYSIOLOGY OF INDUCED HYPOTHERMIA 



time interval during which this initial temperature drop was achieved, and the 

 longest was 10 hours. This was in a man who had not been adequately sedated at 

 first. Simultaneously with the initial drop in temperature, the pulse and respiratory 

 rates decreased, though they did not always drop to normal. 



In some cases with low blood pressures cooling produced a significant rise. 

 Eleven of the 25 patients had systolic pressures below 100 before cooling despite 

 adequate blood replacement. In six of these 11 patients, the systolic level rose above 

 100 after the temperature had been reduced. Four of these six patients survived. 



Severe abnormalities of consciousness or sensorium were common before cooling. 

 Eleven patients were comatose and nine were semi-comatose or delirious. Among 

 the 11 with coma, six recovered, one survived cooling but died more than a month 

 after cooling had been stopped, and four died. Of those who were semi-comatose 

 or severely disturbed, six died and three recovered. 



In table I the mortality is shown for the various clinical groups into which the 

 patients have been separated. Though these groups are small, it would appear that 

 success has been greater among some types of patients than among others. There 

 were more survivors among the head injuries, for example, than among patients 

 suffering complications following major abdominal surgery for cancer. These cancer 

 patients had complications, such as hemorrhage, peritonitis, and lung or intra- 

 peritoneal abscesses. Reduction of the dangerous hyperthermia was not enough to 

 solve their problems. Where fever was more clearly the major issue, as in the pa- 

 tients with brain damage, the results were much better. 



Discussion. In one respect the method has been uniformly successful. It de- 

 cisively reduced the temperature of febrile patients and it kept the temperature 

 down effectively and without great difficulty. The technique is a more certain and 

 controllable method for cooling feverish patients than the commonly employed nurs- 

 ing techniques of using alcohol sponge baths or applying ice bags. It is a better 

 method of cooling because of two special features. The first is the refrigerating 

 blanket. This blanket provides a convenient and accurately controlled way of cool- 

 ing the entire bed surface and thus a large area of the patient's skin. The second 

 important feature is the administration of enough sedation to prevent shivering 

 while the temperature is being lowered. Chlorpromazine has been particularly effec- 

 tive in this role. 



TABLE I 



Mortality among pEBiaLE Patients Treated with Surface Cooling 



Niimhfr 



of ^ 



Clinical type patients Survived Died 



1. Brain damage: 3 head injuries and one cerebrovascular accident. .4 3 1 



2. Major complications following general surgical operations (except 



abdominal cancer) 7 4 3 



3. Major complications following operations for abdominal cancer.. 5 1 4 



4. Following thoracic operations 3 2 1 



5. Following urological operations 2 2 



6. Preoperative (too ill for surgery) 3 (I 3 



7. Burns 1 1 



Totals 25 13 ' 12 



