Orthostatic hypotension during postoperative continuous thoracic epidural bupivacaine-morphine in patients undergoing abdominal surgery

Abstract

Fifty patients undergoing colonic surgery received combined thoracic epidural and general anesthesia followed by continuous epidural bupivacaine 0.25% and morphine 0.05 mg/mL, 4 mL/h, for 96 h postoperatively plus oral tenoxicam 20 mg daily. Heart rate (HR) and arterial blood pressure (BP) were measured at supine rest, during orthostatic stress, and after walking prior to and 24, 48, and 72 h and 48 h postoperatively compared to preoperatively (P < or = 0.008); 16 vs 6 patients presented resting systolic BP values < 100 mm Hg (lower range, 70 mm Hg) post- versus preoperatively (P = 0.048). During orthostatic stress the decrease in systolic BP and concomitant increase in HR was similar post- versus preoperatively (BP, P > 0.3; HR, P > 0.34) and 12 vs 8 patient; (P = 0.45) experienced a systolic BP decrease > 20 mm Hg post- versus preoperatively. After walking, systolic BP was significantly lower postoperatively compared with preoperatively (P < or = 0.01). Epidural infusion was discontinued in three patients due to either persisting resting or orthostatic hypotension. There was no correlation between ASA classification, intraoperative bleeding, or postoperative dizziness and incidence of orthostatic hypotension. The results suggest that patients undergoing abdominal surgery and treated with continuous small-dose thoracic epidural bupivacaine-morphine are subjected to a decrease of BP at rest and during mobilization, but not to an extent that seriously impairs ambulation in most patients.