Spinal or systemic analgesia after extensive spinal surgery: comparison between intrathecal morphine and intravenous fentanyl plus clonidine.

STUDY OBJECTIVE

To compare two different methods of postoperative analgesia after extensive spinal fusion.

DESIGN

Double-blind, randomized study.

SETTING

University-affiliated hospital.

PATIENTS

Twenty four adult patients undergoing scoliosis correction.

INTERVENTIONS

Before the end of surgery, patients received either intravenous clonidine 0.3 micrograms/kg/hr and fentanyl 25 micrograms/kg (after an hourly dose of clonidine 2.5 micrograms/kg) or intrathecal morphine 0.3 mg. A saline infusion was administered to patients receiving morphine intrathecally.

MEASUREMENTS AND MAIN RESULTS

Pain and sedation scores, hemodynamic data, and blood gases were collected in the recovery room at tracheal extubation and then every 2 hours for the next 14 hours. Tracheal extubation was performed at the same time in both groups (i.e., an average of 4 hours after the analgesic regimens were started). Intrathecal morphine provided a mean score of 20 mm on a visual analog scale ranging from 0 mm (no pain) to 100 mm (severe pain), but it resulted in increased PaCO2 at extubation (44 +/- 7 mmHg) and 2 hours later (42 +/- 7 mmHg). PaCO2 was greater than 50 mmHg in four patients receiving intrathecal morphine. Fentanyl-clonidine resulted in equipotent analgesia but was accompanied by sedation (sleeping but arousal by light tactile stimulation) and moderate hypotension (up to 69 +/- 9 mmHg for mean arterial pressure).

CONCLUSIONS

This study shows that there is a major risk of respiratory depression with a single intrathecal dose of morphine 0.3 mg to control postoperative pain after scoliosis surgery. Systemic clonidine-fentanyl may be a possible approach to the postoperative pain treatment of this surgery.