The changes in total body water in patients with prolonged anesthesia and surgery

: We studied the influence of prolonged anesthesia and surgery on total body water (TBW) with tetrapolar bioelectrical impedance analysis (BIA). Eight patients who underwent prolonged anesthesia were selected as the subjects of the study and were compared with nine patients who underwent surgery of less than 3 hours. Plasma hormone concentrations were also examined. In the prolonged anesthesia patients, TBW increased significantly as compared with those of the patients who underwent short surgery (P less than 0.05). TBW showed the most remarkable increase on the first post operative day. Plasma ADH and aldosterone concentrations increased in the patients of both groups. However, we could not find a significant relationship between TBW and plasma hormone concentrations. BIA seems to be a useful method to estimate TBW during perioperative periods. However, further detailed investigation would be necessary to obtain a reliable technique in such an unstable condition.