Effect of high-volume systematic local infiltration analgesia in Caesarean section: a randomised, placebo-controlled trial.

BACKGROUND

Pain after Caesarean section is often treated with opioids with a risk of side effects. Wound infiltration with local anaesthetics is effective and has few side effects, but volume vs. dose concentration has not been examined.

METHODS

Ninety patients scheduled for elective Caesarean section included in a randomised, double-blinded, placebo-controlled trial receiving infiltration with 50 ml ropivacaine 0.5% or 125 ml ropivacaine 0.2% or 50 ml 0.9% saline (placebo) during surgery. Surgery was performed under lumbar spinal anaesthesia. Primary endpoint was post-operative pain. Secondary endpoints were rescue analgesic, post-operative nausea and vomiting, time spent in the postanesthesia care unit (PACU) and time to first mobilisation.

RESULTS

No difference in pain response between groups, but time until maximum pain score was prolonged in the ropivacaine 0.5% group compared with the placebo group (P = 0.0493). The administration of ketobemidone at 24 h post-operatively in the ropivacaine 0.5% group was reduced compared with the placebo group (P = 0.020), and between the ropivacaine 0.2% group and the ropivacaine 0.5% group (P = 0.044). No significant differences between groups were found concerning time spent in the PACU, to first mobilisation or in number of women with nausea/vomiting (P ≥ 0.05). No complications related to ropivacaine were observed.

CONCLUSIONS

Systematic infiltration with a high concentration, low volume compared with low concentration, high volume showed no significant effect on post-operative pain intensity. However, a statistically significant, but clinically limited opioid sparing effect was demonstrated compared with placebo in the high concentration, low volume group.