The effective duration of analgesia after intrathecal morphine in patients without additional opioid analgesia: a randomized double-blind multicentre study on orthopaedic patients.

BACKGROUND AND

OBJECTIVE

To know whether the application of patient-controlled analgesia devices could be avoided if intrathecal morphine is given in combination with spinal anaesthesia.

METHODS

In a randomized, double-blind multicentre study, 188 orthopaedic patients were randomized to receive intrathecally placebo, 0.1 mg morphine or 0.2 mg morphine in addition to 15 mg bupivacaine. The primary outcome parameter was the number of patients without any additional request for opioid during a period of 72 h after surgery.

RESULTS

Patients with 0.1 or 0.2 mg morphine showed a significant reduction in opioid requests compared with placebo during 72 h after surgery (P = 0.0001). At 24 h after surgery, the rate of patients who required additional opioid analgesia was 71% in the placebo group, 51% in the 0.1 mg morphine group and 31% of the patients in the 0.2 mg morphine group. After 0.2 mg morphine, systemic opioid requirements at 24 h were significantly lower than those in patients with 0.1 mg morphine (P < 0.05). Intrathecal morphine was not associated with an increased frequency of respiratory depression. Forty per cent of patients with intrathecal morphine did not ask for systemic opioids.

CONCLUSION

Intrathecal morphine in a dose of 0.1 and 0.2 mg provides effective analgesia for up to 48 h without any need for systemic opioids at all in many patients.