Post operative analgesia with intrathecal morphine

Sixty eight ASA I and II patients between 18 and 84 years who underwent minor to medium surgery were studied retrospectively. They were divided into 2 groups, on basis on intrathecal morphine administration.

Group I received spinal anesthesia with bupivacaine 12.5-15 mg. Group II received in addition 0.1 mg morphine (preservative free) [MO PF]. Pain assessment, up to 24 hours, was evaluated by the need of salvage medication namely pethidine i.m. (intramuscular).

The groups matched for demographic distribution. Twenty one out of 30 patients in Group I needed salvage medication, compared to 6 out of 38 patients in Group II (p < 0.005). Minor complications of intrathecal morphine were noted. These were higher in Group II compared to Group I; itching and pruritus (14 vs. 1); urinary retention (2 vs. 0); nausea and vomiting (1 vs. 0) (p < 0.005).

This study showed that a single low dose of intrathecal morphine with bupivacaine provides better quality post-operative analgesia than bupivacaine alone, and might offer enough analgesia for minor to medium cases up to 24 hours post-op. However, some side effects have to be taken into consideration.