OBJECTIVETo investigate the effect of controlled hypotension using different drugs on gastrointestinal perfusion and bleeding volume in nasal endoscopic surgery.

METHODSThirty ASA class I or II patients scheduled for nasal endoscopic surgery were randomized into three groups, including a routine general anesthesia group (group A) and two controlled hypotension groups (groups B and C). After anesthesia induction, anesthesia was maintained with 1%-2% isoflurane and vecuronium. ECG, mean arterial blood pressure (MAP), heart rate (HR), SpO(2) and PETCO(2) were continuously monitored. TRIP tonometry catheter 14 F was inserted into the stomach and connected to Tonocap (Datex-Ohmeda, Finland ). In groups B and C, hypotension was induced with isoflurane (1%-2%) and sodium nitroprusside (0.3-3 microg.kg(-1).min(-1)), and with isoflurane (1%-2%) and glonoine (0.5-5 microg.kg(-1).min(-1)), respectively, and the MAP was reduced to 50-55 mmHg in 10-15 min. In groups B and C, blood samples were taken for blood gas analysis after anesthesia (T(0)), after acute hypervolemic hemodilution (T(1)), at 30 and 60 min after controlled hypotension (T(2) and T(3)), and 30 min after recovery from hypotension (T(4)). In group A, blood samples were taken at different time points in the perioperative period.

RESULTSThe patients in groups B and C had smaller bleeding volume than those in group A. HR was decreased after moderate acute hypervolemic hemodilution, and increased after controlled hypotension (T(2) and T(3)) in comparison with that at T(1) to a level similar to that at T(0). No significant changes were found in pHi at T(2) and T(3) in comparison with that at T(1) in the three groups.

CONCLUSIONWhen appropriate measures are taken, induced hypotension at 50-55 mmHg does not necessarily produce disturbance in gastrointestinal perfusion. Induced hypotension with glonoin can decrease the bleeding volume better than sodium nitroprusside in nasal endoscopic surgery.