Comparative study of continuous extrapleural intercostal nerve block and lumbar epidural morphine in post-thoracotomy pain.

OBJECTIVES

To compare the efficacy of continuous extrapleural intercostal nerve block with bupivacaine 0.5% in 1:200,000 epinephrine and continuous lumbar epidural block with morphine in controlling post-thoracotomy pain and to measure serum bupivacaine concentrations during extrapleural infusion.

DESIGN

A prospective, randomized, controlled trial.

SETTING

St. Joseph's Hospital, Hamilton, Ont., a tertiary care teaching centre.

PATIENTS

Sixty-one patients booked for elective thoracotomy were randomized by scaled envelope to two groups.

INTERVENTIONS

Group A received a continuous extrapleural intercostal nerve block with bupivacaine 0.5% in 1:200,000 epinephrine as a bolus of 0.3 mL/kg followed by an infusion of 0.1 mL/kg every hour for 72 hours. Group B received a continuous lumbar epidural block with morphine as a bolus of 70 g/kg followed by an infusion of 7 g/kg every hour for 72 hours.

MAIN OUTCOME MEASURES

Pain was assessed by a linear visual analogue scale (VAS) pain score. The cumulative amount of "rescue" intravenous morphine used, and serum bupivacaine concentrations were measured as secondary outcomes.

RESULTS

Pain control was the same in both groups as assessed by linear VAS score (p = 0.33). The cumulative dose of intravenous morphine for supplemental analgesia was statistically significant between the groups: group A patients used more morphine than group B (p < 0.05). Accumulation of serum bupivacaine was present with no clinical toxicity.

CONCLUSIONS

There is no significant difference in the degree of post-thoracotomy pain control measured by the VAS score when analgesia is provided by continuous extrapleural intercostal nerve block with bupivacaine 0.5% in 1:200,000 epinephrine or lumbar epidural block with morphine. Larger amounts of rescue analgesia were used by patients in the continuous extrapleural group with bupivacaine than those in the continuous lumbar epidural block with morphine. Serum bupivacaine concentrations rise without clinical toxicity.