Perioperative transversus abdominis plane (TAP) blocks for analgesia after abdominal surgery: Cochrane systematic review

Abstract

Assessed as up to date: 2010/11/08

Background

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.

Author(s)

Charlton Shona, Cyna Allan M, Middleton Philippa, Griffiths James D

Summary

TAP blocks (nerve blocks) for analgesia after abdominal surgery

Poorly controlled pain after abdominal surgery is associated with a variety of unwanted post-operative consequences, including patient suffering, distress, confusion, chest and heart problems, and prolonged hospital stays. Traditionally, pain relief is provided by: medications injected in to a vein using a 'drip' such as morphine or paracetamol; administering local anaesthetic into the skin around the surgical wound; or by providing epidural pain relief where local anaesthetic and other pain relieving medications are injected through a fine plastic tube into the epidural space of the lower back - numbing the nerves that supply the abdomen. Following surgery, Transversus Abdominis Plane (TAP) block is a relatively new way of anaesthetising nerves which numb the abdomen after surgery in order to help improve patient comfort after their surgery. In the past few years, there has been increasing research and interest describing how TAP blocks are being used for pain relief in both adults and children having abdominal surgical procedures. However, there have not been any systematic reviews evaluating the effectiveness of the TAP block in reducing pain after surgery. We have searched for research investigating the effectiveness of rectus sheath (a similar block to TAP) and TAP blocks in providing pain relief after abdominal surgery. We have included eight studies, with a total of 358 participants in this review, that show some limited evidence that TAP blocks improve pain relief after abdominal surgery. More research is indicated, comparing TAP blocks with other standard methods of pain relief such as, morphine medication, epidural analgesia and local anaesthetic injection into and around the surgical wound. There are many studies currently underway or awaiting publication which assess the effectiveness of the TAP block and compare it with other techniques. We intend to include these studies in an updated version of this review in the near future.

Reviewer's Conclusions

Implications for practice

There is limited evidence that the use of perioperative TAP block with usual care reduces opioid consumption and pain scores after abdominal surgery in comparison with usual care alone or placebo. There is no apparent reduction in postoperative nausea and vomiting or sedation from the small numbers of studies to date. The improvement appears to be greatest at 24 hours postoperatively, but may persist until 48 hours or beyond. There is no apparent reduction in postoperative nausea and vomiting or sedation from studies to date, which are few and involving small numbers of participants. There are insufficient data on method of block localisation, block timing, doses and volumes of local anaesthetic required, and adverse effects to enable any conclusions about block methodology to be drawn.

Implications for research

Future studies should address not only the efficacy of TAP and rectus sheath blocks in specific types of surgery, but also the influence of:

• method of block localisation,

• timing of block (after induction or at the end of surgery),

• single-shot versus continuous infusion of drug,

• type, volume and concentration of local anaesthetic drug used,

• level of experience of block operator.

In addition further study is required comparing TAP block with other methods of postoperative analgesia and as an analgesia adjunct to usual care. However, there are many studies currently underway or awaiting publication which assess these differences. We intend to include these in an updated review in the near future.