Perioperative transversus abdominis plane (TAP) blocks for analgesia after abdominal surgery

Abstract

The transversus abdominis plane (TAP) block is a peripheral nerve block which anaesthetises the abdominal wall. The increasing use of TAP block, as a form of pain relief after abdominal surgery warrants evaluation of its effectiveness as an adjunctive technique to routine care and, when compared with other analgesic techniques. To assess effects of TAP blocks (and variants) on postoperative analgesia requirements after abdominal surgery. We searched specialised registers of Cochrane Anaesthesia and Cochrane Pain, Palliative and Supportive Care Review Groups, CENTRAL, MEDLINE, EMBASE and CINAHL to June 2010. We included randomised controlled trials (RCTs) comparing TAP block or rectus sheath block with: no TAP or rectus sheath block; placebo; systemic, epidural or any other analgesia. At least two review authors assessed study eligibility and risk of bias, and extracted data. We included eight studies (358 participants), five assessing TAP blocks, three assessing rectus sheath blocks; with moderate risk of bias overall. All studies had a background of general anaesthesia in both arms in most cases.Compared with no TAP block or saline placebo, TAP block resulted in significantly less postoperative requirement for morphine at 24 hours (mean difference (MD) -21.95 mg, 95% confidence interval (CI) -37.91 to 5.96; five studies, 236 participants) and 48 hours (MD -28.50, 95% CI -38.92 to -18.08; one study of 50 participants) but not at two hours (all random-effects analyses). Pain at rest was significantly reduced in two studies, but not a third.Only one of three included studies of rectus sheath blocks found a reduction in postoperative analgesic requirements in participants receiving blocks. One study, assessing number of participants who were pain-free after their surgery, found more participants who received a rectus sheath block to be pain-free for up to 10 hours postoperatively. As with TAP blocks, rectus sheath blocks made no apparent impact on nausea and vomiting or sedation scores. No studies have compared TAP block with other analgesics such as epidural analgesia or local anaesthetic infiltration into the abdominal wound. There is only limited evidence to suggest use of perioperative TAP block reduces opioid consumption and pain scores after abdominal surgery when compared with no intervention or placebo. There is no apparent reduction in postoperative nausea and vomiting or sedation from the small numbers of studies to date. Many relevant studies are currently underway or awaiting publication.