ABSTRACT
Objective To investigate the effects of remifentanil-indueed controlled hypoteusion (CH) on the cerebral oxygen metabolism in patients undergoing radical operation for gastric cancer. MethodsForty-two ASA Ⅰ or Ⅱ patients (26 male, 16 female) aged 30-64 yr with body nuts index < 30 kg/m2 undergoing elective radical operation for gastric cancer were randomly divided into 3 groups (n = 14 each): group R remifentanil-induced controlled hypotension; group N sodium nitroprusside-induced CH and group C normal BP. Radial artery was cannulated for continuous BP monitoring and blood sampling. A catheter was inserted into right internal jugular vein and advanced cephalad until jugular bulb for blood sampling. MAP, HR, ECG and SpO2were continuously monitored. Anesthesia was induced with midazolam 0.1 mg/kg, fentanyl 5 μg/kg, propofol 2 mg/kg and vecuronium 0.08 mg/kg and maintained with isoflurane (end-tidal concentration 1. 1% ), iv infusion of propofol (50-100 μg·kg-1·min-1 ) and remifentanil (0.1 μg·kg-1·min-1) and intermittent iv boluses of vecuronium. The patients were mechanically ventilated (VT 8-10 ml/kg, RR 12 bpm, I: E 1:1.5) after tracheal intubation. End-tidal CO2was maintained at 30-35 mm Hg. CH was started after abdomen was opened. In group R the remifentanil infusion rate was increased from 0.1 μg·kg-1·min-1 in 0.05 μg·kg-1·min-1 increment every minute until the1 μg·kg-1min-1 in 0.5 μg·kg-1·min-1 increment every minute until the desired BP was achieved. MAP was reduced to 70% of the baseline value but never below 50 mm Hg. CH induction time and BP recovery time were recorded. Arterial and jugular bulb venous blood samples were obtained before induction of anesthesia (T0), immediately before induction of CH (T1), at 10 and 30 min of CH (T2,3) and 20 min after termination of CH (T4). The arterial and jugular bulb venous O2content difference (Da-jvO2) and cerebral O2extraction rate ( CERO2) were calculated. The difference between arterial and jugular bulb venous blood lactic acid concentration (Da-jvL) was also calculated. Results The CH induction time and BP recovery time were significantly longer in group R than in group N, but BP was stabler during CH in group R than in group N. Compared with group C, Da-jvO2, CERO2and Da-jvL were significantly decreased in group R, while CERO2and Da-jvL were significantly increased in group N. Conclusion Remifentanil can effectively induce CH and reduce cerebral O2consumption in patients undergoing radical operation for gastric cancer.