['STUDY OBJECTIVES To determine if moderate controlled hypotension can improve the dryness of the surgical field in endoscopic sinus surgery.', 'Randomized, prospective study.', 'University-affiliated hospital.', '32 ASA physical status I and II adult patients undergoing endoscopic sinus surgery.', 'All patients were premedicated orally with chlorazepate. Patients in Group H received 12.5 mg captopril orally prior to surgery. Anesthesia was provided using an intravenous (IV) technique supplemented with nitrous oxide (N(2)O); anesthesia was maintained with boluses of 2 mcg/kg fentanyl and a propofol infusion at rates between 3 and 9 mg/kg/h at the discretion of the anesthetist. In Group H, sodium nitroprusside was infused at a rate of 1 to 2.5 mcg/kg/min to maintain moderate controlled hypotension with mean blood pressure of 65 to 75 mm Hg.', 'Arterial blood pressure was assessed via the radial artery. Readings were recorded prior to intubation, immediately after intubation, at the start of surgery, then at 5, 15, 30, 45, and 60 minutes intraoperatively, and at the end of surgery. Intraoperative blood loss, dryness of the surgical field, adrenocorticotropic (ACTH) hormone, arginin-vasopressin (AVP), cortisol, and the preoperative and postoperative psychomotoric function were examined. At the start of surgery and thereafter, MAP increased in Group N but not in Group H. Throughout surgery, MAP was significantly lower in Group H than in Group N. Blood loss, dryness of the surgical field, ACTH, AVP, and cortisol levels, and psychomotoric function were not significantly different between the groups.'] Does moderate controlled hypotension with sodium nitroprusside improve surgical conditions or decrease blood loss in endoscopic sinus surgery?