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784 CHANGES IN RENAL FUNCTION ASSOCIATED WITH MAJOR SURGICAL PROCEDURES IN ELDERLY PATIENTS -WITH SPECIAL REFERENCE TO CREATININE CLEARANCE AND FREE-WATER CLEARANCE- Shingo TAKEMOTO, Jun-ichi MIURA, Tetsuo MATSUDA and Tetsu KATAOKA Department of Surgery, School of Medicine, Showa University (Director: Prof. Jun-ichi ISHII) Abstract - Elderly patients usually show renal hypofunction and a decrease in body fluid due to ageing and are liable to suffer renal hypofunction after operation because of marked effect on the renal function during and after surgery. For the purpose of studying changes in the renal function associated with major surgical procedures in elderly patients, we determined creatinine clearance, free-water clearance, creatinine and blood urea N on a time course basis before and after operation in 51 patients who underwent laparotomy. The cases were divided into three groups, namely, the non-transfusion group aged under 65 years (group A : 21 cases), as was the control group, the non-transfusion group aged over 65 years (group B : 15 cases) and the transfusion group over 65 years (group C : 15 cases), and a comparative study was made of these groups. The preoperative level of creatinine clearance tended to be low in groups B and C compared with group A, with 74.1 }36.5 ml/min in group A, 54.6 }15.5 ml/min in group B and 57.6 }18.1 ml/min in group C. A look at changes after operation showed that the level fell off after operation and rose gradually with the lapse of time thereafter in all of the three groups. Whereas group A and group C followed a relatively similar course with the preoperative level restored within 12 hours after operation, the recovery was delayed considerably in group B. A significant difference was noted between group B and group C from three hours to 12 hours after operation (p<0.05). The absolute value for preoperative level of free-water clearance tended to be low in group B and group C compared with group A, with 0.81 }0.49 ml/min in group A, 0.52 }0.31 ml/min in group B and 0.57 }0.35 ml/min in group C. A look at changes after operation showed that the value closed to zero and fell off gradually thereafter in all of the three groups. In group A, the absolute value closed to zero after operation, fell off to 0.28 }0.13 (34/0 of the preoperative level) one hour after operation, but recovered markedly to 0.67±0.42 ml/min three hours after operation and returned to the preoperative level 12 hours after operation. In group B, on the other hand, the absolute value closed to zero after operation, fell off to 0.09 }0.07 ml/min (17% of the preoperative level) one hour after operation and showed tendency to slight recovery with 0.16 }0.07 ml/min three hours after operation, but recovery to the preoperative level was delayed considerably. In group C, the recovery was better than in group B, and the preoperative level was restored 12 hours after operation. There was a significant difference between group B and group C from three hours to 12 hours after operation (p<0.05). Whereas creatinine clearance and free-water clearance showed a marked change associated with surgical procedures, creatinine and blood urea N exhibited no marked change. From the above, it was understood (1) that the effect of surgical procedures on the function of the glomerulus and the renal tubules is great, (2) that preoperative transfusion is particularly effective for maintaining the postoperative renal function and (3) that determining preoperative and postoperative creatinine clearance and free-water clearance on a time course basis makes it possible to grasp changes in the postoperative renal function early for sure. These results appear to have very important implications for prediction and prevention of postoperative acute renal insufficiency in elderly patients. 784