Pre-emptive epidural analgesia does not reduce long-term pain after thoracotomy

Clinical bottom line

Using preoperative epidural analgesia rather than after operation makes no difference to pain six months after thoracotomy.

Reference

CL Bong et al. Effects of preemptive epidural analgesia on post-thoracotomy pain. Journal of Cardiothoracic and Vascular Anesthesia 2005 19: 786-793.

Background

Thoracotomy is a painful surgical procedure, and is also associated pain that persists long after surgery. A systematic review of pain after surgery (Bandolier 103-4) reported that at least half of patients having thoracotomy at about one year. It has been widely believed that using analgesic interventions before the onset of surgical pain can reduce long-term pain after surgery, though most studies have been relatively small and with methodological shortcomings.

Systematic review

The review searched a number of electronic databases.

Date review completed: Search to December 2004
Number of trials included: 6, all randomised, all with attempts at blinding patients, physicians, or assessors.
Number of patients: 478 adult patients undergoing unilateral thoracotomy.
Control groups: the review compared thoracic epidural analgesia begun before surgical incision to the same begun after completion of surgery.
Main outcomes: Pain at 24 and 48 hours after surgery, and at six months, measured on 10 point scores in the postoperative period.

Results

All six studies used epidural local anaesthetic, with intravenous opioid in five of them.

At 24 hours there was no difference in pain scores. At 48 hours the difference was 0.6 points (on a 10-point scale). Average pain scores were low, and differences only occurred in two studies with control pain scores above 2.5 (on a 10-point scale).

Three studies reported absence of pain at six months (Figure 1). There was no difference between the groups, with 59/97 (61%) with no pain with preoperative epidural, and 56/109 (51%) with postoperative epidural. The relative risk was 1.2 (0.9 to 1.5).

Figure 1: Pain at six months with pre-emptive and postoperative thoracic epidural analgesia

Comment

There is no evidence that pre-emptive epidural with local anaesthetic prevents long-term thoracotomy pain. Although there is relatively little good evidence, with only three trials and 206 patients, no large effect can be expected. It was noteworthy that the largest trial was completely negative.