[Perioperative water and electrolyte metabolism and its abnormalities in aged patients]

The number of aged surgical patients is increasing due to the increase of aged people in the general population. Aged surgical patients above 65 years of age constituted about 30% of all ICU patients in our institution. Perioperative care for aged patients has now become one of the most important clinical activities in the ICU. The perioperative management for those aged patients should be performed with great care because these patients have some abnormalities in water and electrolyte metabolism. Aged patients showed decreased blood levels of atrial natriuretic peptide (ANP) and decreased creatinine clearance even in the preoperative period. The ANP level and the creatinine clearance showed significant negative correlation, indicating that one of the reasons for impaired renal function among aged patients could be the decreased ANP level in blood. The intraoperative insults to the aged surgical patients undergoing radical operation for esophageal cancer tended to be smaller compared to that in the younger patients. Intraoperative infusion volume and urinary output were also smaller in the aged group compared to those in the younger group. The postoperative infusion therapy in the ICU mainly consisted of intravenous hyperalimentation with decreased Na content and the transfusion of fresh frozen plasma. This regimen should be more suitable for the aged patients. Even though the aged and the younger group received the same infusion therapy during their postoperative ICU stay up to the 7th day, the aged patients showed the tendency of Na and Cl retention and increase in anion gap. However, these abnormalities in water and electrolyte metabolism were not so severe as to cause clinical symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)