212 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



tension and renal function within normal range. There was a sHght increase in 

 glomerular filtration rate during pentothal anesthesia. At 94° F. there was a slight 

 depression in blood pressure, renal blood flow and glomerular filtration rate. There 

 was an increase in urine volume probably due to decreased tubular reabsorption of 

 glomerular filtrate resulting from the hypothermia. A further moderate depression 

 in blood pressure and renal function occurred when the rectal temperature was 

 reduced to 89° F. During aortic occlusion, renal function was nil. Immediately 

 after release of the clamps, renal function partially returned but remained much 

 below the preclamping, hypothermic level. After rewarming, renal function was 

 largely restored though still somewhat below control values. A week later, a slight 

 depression was still evident. 



Case 3. — A 56-year-old white male had a fusiform aneurysm of the descending 

 thoracic aorta. The aneurysm was resected and replaced with a lyophilized homo- 

 graft. Hypothermia to a level of 88° F. was carried out by ice water immersion 

 under pentothal anesthesia. The period of aortic occlusion was 40 minutes. 



As illustrated in figure 13, there was no significant change in renal function dur- 

 ing anesthesia. During hypothermia, renal blood flow and glomerular filtration 

 rate were reduced almost 50 per cent. The usual relative increase in urine volume 

 was not observed until the patient was partially revvarmed. No determinable func- 

 tion was present during aortic occlusion. Immediately after rewarming, renal 

 function approached control values. 



Case 4. — A 36-year-old Negro female had a fusiform aneurysm of the descend- 

 ing thoracic aorta. Hypothermia was induced with refrigeration blankets and the 

 aneurysm was resected and replaced with a lyophilized homograft. The period 

 of aortic occlusion was 35 minutes with a rectal temperature of 91° F. (table III). 



Again, in this patient, the characteristic moderate reduction in renal function 



8r 



7 



c 6 

 I 

 e 5 



S 3 



I600r 

 1400 

 1200 



^ 1000 



4 



u; 800 



5 600 

 ■ '^^ 400 

 200 

 



160 

 140 

 120 



^ 100 



<; 

 o 



■g 80 



>- 60 



40 



20 



— 



AOftiC 

 Occlusion 

 I 94« 



^^ Reno I Blood Flow 



^^ Glomerulor Filtration Rots 



purine Volume 



^ 



l_ 



6am 7 



II 12 



noon 



6pm 



Fig. 13. — The effect of anesthesia, hypothermia and aortic occlusion under hypothermia on ronnl 

 function in a 56-year-oId white male who had a homograph replacement of the aorta. 



