Effect of acute arterial hypertension on morphine requirements and postsurgical pain

•Acute hypertension on morphine's requirements after surgery was studied.•Intraoperative hypertension reduced postoperative morphine requirements and pain.•Administration of opioids during the intraoperative period induces hyperalgesia.

Study objectiveThe study objective was to establish the impact of acute hypertension on morphine's requirements after laparoscopic cholecystectomy.DesignThe design was a randomized, simple blinded study.SettingThe settings were operating room, postoperative recovery area, and first postoperative day.PatientsThere were 50 patients, American Society of Anesthesiologists I-II, aged 18-50 years, undergoing elective laparoscopic cholecystectomy with general anesthesia.InterventionsAnesthetic management was standardized using propofol for induction, isoflurane for bispectral index (BIS) ranging between 40 and 60, and remifentanil maintained at a constant rate of 0.4 μg kg per minute throughout surgery in all patients. Once intubated, patients were randomly allocated to 1 of 2 groups: hypertensive group: systolic arterial blood pressure was maintained with phenylephrine infusion 20%-30% over baseline; control group: systolic arterial blood pressure was maintained 20%-30% below baseline. All surgical incisions were infiltrated with bupivacaine 0.5%, and every patient received ketorolac 60 mg intravenous. Patient-controlled analgesia with morphine intravenous was used for postoperative analgesia.MeasurementsPain visual analogue scale scores, arterial blood pressure, and hyperalgesia were assessed at recovery room every 15 minutes during the first 2 postoperative hours and then at 6, 12, and 24 postoperative hours. Cumulative morphine consumption was registered at 2 and 24 postoperative hours.Main resultsThe cumulative morphine consumption in the control group was around 18 mg compared with 6 mg in the hypertensive group (P = .019). During the first 75 minutes after surgery, the control group had higher visual analogue scale score pain compared with hypertensive group (P = .005).ConclusionsThe intraoperative acute generation of mild hypertension with phenylephrine reduced postoperative morphine consumption and pain scores after laparoscopic cholecystectomy.