Effect of acute arterial hypertension on morphine requirements and postsurgical pain

Abstract

Study objective: The study objective was to establish the impact of acute hypertension on morphine's requirements after laparoscopic cholecystectomy.

Design: The design was a randomized, simple blinded study.

Setting: The settings were operating room, postoperative recovery area, and first postoperative day.

Patients: There were 50 patients, American Society of Anesthesiologists I-II, aged 18-50 years, undergoing elective laparoscopic cholecystectomy with general anesthesia.

Interventions: Anesthetic 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.

Measurements: Pain 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 results: The 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).

Conclusions: The intraoperative acute generation of mild hypertension with phenylephrine reduced postoperative morphine consumption and pain scores after laparoscopic cholecystectomy.

Keywords: Hyperalgesia; Hypertension; Postoperative pain.