Renin-aldosterone system and atrial natriuretic peptide during anesthesia in orthopedic patients over 80 years of age

Study Objectives: To investigate the changes in plasma atrial natriuretic peptide, renin activity, and aldosterone during isoflurane anesthesia in patients over 80 years. Design: Prospective,, randomized controlled study. Setting: Operating rooms and postanesthesia recovery) room of Hi,rosaki University Hospital a,and Hakodate Watanabe: Hospital Patients: 36 patients undergoing reduction of femur neck fracture (18 patients ranging in age from 80 to 99 years and Is patients ranging in, age from 40 to 59 years as control). Intervention: In all patients, anesthesia was induced with intrvenous (ni) thiopental sodium 3 to 5 mg/kg succinylcholine 0.5 to 1.0 mg/kg for facilitating traheal intubation and was maintained with( 1.2 to 2.0 % isoflurane, in 50 oxygen. Measurements and Main Results: Plasma atrial natriuretic peptide (ANP)l plasma renin activity (PR I), and plasma aldosterone (PA) levels were assayed. Blood samples were obtained on the following occasions: before the induction of anesthesia, IS minutes of skin incision, 90 minutes after anesthesia induction, and the 60 minutes after the end of surgery. Plasma renin activity, and P=ilevels in patients from 40 to 59 years increased significantly 90 minutes after ind induction, whereas PRA and PA levels in patients over 80 years were unchanged. There were significant differences in PRA and Pii levels between both groups at any time of measurements. Plasma ANP levels of patients over 80 years un-e significantly elevated err Ba minutes induction. Plasma ANP levels in patients over 80 years, at 90 minutes nafter the induction and 60 minutes after the end of surgery were significantly higher, than those of patients from 40 to 59 years. Plasma,renin activity in hypertensive patients over 80 years at 90 minutes after the induction was significantly lower than that observed,ed in normotensive patients. The renal loss of sodium was increased in the hypertensive patients. Conclusions: Orthopedic patients over 80 rears of age have decreased PRA and PA;, increased ANP, and renal loss of sodium as compared with patients 40 to 59 years, dating isoflurane anesthesia. Plasma renin activity at 90 minutes after induction urns decreased in hypertensive patients over 80 gents, but Prl and ANP were not affected by hypertension during anesthesia. (C) 1999 by Elsevier Science Inc.