406 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



50-1 



Number 



of 



Procedures 



40- 



30- 

 20- 

 10- 



PROCEDURES 



I I DEATHS 







CO IZJ kzzji iS 



2-4 



4-6 



6-8 



8-10 



Circulatory Occlusion Times (minutes) 



Fig. 2. — Mortality in relation to duration of circulatory occlusion (84 procedures). 



higher centers for the periods of circulatory occlusion practised. A peripheral 

 neuropathy, however, did frequently occur. This was carefully evaluated by our 

 neurology service and the conclusion was reached that it w'as a complication of our 

 method of surface cooling. The lesion was a direct injury to the peripheral nerves 

 of the extremities due to cold. Time is an important factor. Few lesions appeared 

 when the patient remained in ice water less than thirty minutes. For this reason, 

 we now make it a practice to elevate the extremities above the water level after 

 that period of time. Fortunately, all of the patients have experienced a return to 

 normal function during the postoperative period. 



CLINICAL EXPERIENCE AND RESULTS 



In table I is seen the various diagnoses for which hypothermia was used in 

 conjunction with standard closed operative procedures. In such small groups, the 



TABLE I 



Closed Cardiac Procedures 



Improved 



Diagnosis Patient? 



Tricuspid atresia 3 



Tetralogy of Fallot 2 



Single ventricle 1 



Idiopathic pulmonary hypertension 1 



Patent ductus arteriosus 6 



Aberrant pulmonary veins 2 



Aorto-jiulmonary window 1 



Auricular septal defect 1 



Aortic stenosis 1 



Aortic regurgitation 2 



Mitral stenosis and rcgurgitatidu 4 



24 



11 



