Preemptive analgesia with ropivacaine for pars plana vitrectomy: randomized controlled trial on efficacy and required dose.

BACKGROUND

The rationale of preemptive analgesia in ocular surgery is avoiding central sensitization because of nociceptive stimuli. The applicability in clinical practice has been argued because evidence for a relevant effect is missing. The present study attempts to demonstrate a clinically relevant pain reduction by preemptive peribulbar ropivacaine injection.

METHODS

Sixty patients scheduled for vitrectomy under general anesthesia between March and June 2007 were randomly assigned to receive 0.75% ropivacaine with 75 IU of hyaluronidase as peribulbar injection of 1, 3, or 5 mL before or 5 mL after surgery. Control subjects were 30 patients without any additional analgesic treatment. Groups were compared regarding procedure duration, consumed amount of analgesics during and after surgery, and pain 1, 3, and 24 hours postoperatively.

RESULTS

Postoperative pain was most marked in control subjects and in the group that received the injection after surgery. Before surgery, the dose of 5 mL of ropivacaine was most effective (postoperative pain median = 0), whereas patients who had received 1 mL or 3 mL reported some pain.

CONCLUSION

The study highlights the benefit of the concept of preemptive analgesia in general: the peribulbar injection of 5 mL of 0.75% ropivacaine before surgery provides a substantial benefit in terms of analgesic demand and postoperative discomfort.