Remifentanil and Stress Hormones Response

Fifty Caucasian patients, aged 20-70 years, with American Society of Anesthesiologist physical status I-II, undergoing laparoscopic cholecystectomy were enrolled. Exclusion criteria were: patient refusal, thyroid disorders, diabetes mellitus, BMI \> 30, use of corticosteroids, benzodiazepines or antipsychotics drugs. No patient received premedication. Before entering the operating room, venous access was established (18 G in the antecubital vein) where the first blood sample (Time 0) was collected to measure adrenocorticotropic hormone (ACTH), Cortisol, Growth hormone (GH) and prolactin (PRL) levels. Then a second venous access was established (18 G on the other arm) to start a fluid infusion (normal saline to replace half of the water deficit from preoperative fasting followed by a maintenance infusion of 2 ml/kg/h). Heart Rate (HR), Non Invasive Blood Pressure (NIBP), Bispectral Index (BIS), End-tidal CO2 (EtCO2) were recorded every 5 minutes. Patients were randomly assigned to receive two different dosages of remifentanil: 0,15 mcg/kg/min (group A) and 0,30 mcg/kg/min (group B) for the induction and the maintenance of anesthesia, using a computer generated randomization table (Table I). Anesthesia was induced with propofol 2 mg/kg, cisatracurium 0,15 mg/kg and remifentanil infusion of 0,15 mcg/Kg/min (Group A) or 0,3 mcg/Kg/min (Group B) was started. Anesthesia was maintained with desflurane at a variable concentration in order to maintain the BIS between 40 and 60. The second blood sample was collected at the trocar insertion (Time 1), and the third sample one hour after the end of the surgery (Time 2). Postoperative analgesia was standardized using intravenous acetaminophen 1 g and morphine 0,1 mg/kg 30 minutes before the end of the surgery. Rescue analgesia in Recovery Room was provided by intravenous tramadol 1 mg/Kg.