[The effect of preoperative food and fluid restrictions on various metabolic parameters in geriatric patients]

This clinical investigation was carried out in order to determine whether the 10-12 hr food and fluid restrictions imposed before elective operations have detrimental effects on older patients according to various metabolic parameters. Thirty male urological patients aged between 60 and 90 years were chosen for study (group I 60-70 years, group II 70-80 years, group III 89-90 years). The following parameters were measured at 7 p.m. the evening before the operation, and at 7. a.m. on the morning of operation: body weight, hematocrit, blood-gas analysis, electrolytes, serum osmolality, urea, creatinine, total protein with electrophoresis and blood glucose. Urine was collected during the period of abstinence and osmolality, electrolytes, total nitrogen, creatinine and urea were estimated. All patients showed a reduced creatinine clearance to a degree that was expected for their age. In all three groups a significant weight reduction (p less than 0,001) occurred during the time of observation. The 12 hr urine volume increased from one age group to the next whereas perspiration decreased, indicating deficient thermal regulations in older patients. The hypohydration on the morning of operation, especially in group II and III, marked a relatively lower hematocrit and hypoproteinemia. In all three groups the urea and creatinine values were slightly lower in the morning than in the evening before, indicating the occurrence of further hypohydration due to fasting. The low elimination of total nitrogen, urea, and creatinine in the urine could be an indication that the 12 hr food and fluid restriction caused no marked catabolism. Our study shows that geriatric patients are indeed able to compensate for a 12 hr-period of abstinence. When however, these patients also have to undergo an operation, possibly associated with a considerable loss of body fluids or when restriction of oral intake extends to 16-20 hrs, decompensation may rapidly occur leading to deleterious consequences.