Trial of a Transversus Abdominis Plane (TAP) Block in Laparoscopic Colorectal Surgery
Condition: Post-operative Pain; Postoperative Nausea; Postoperative Complications
MeSH terms: Pain, Postoperative; Postoperative Complications; Postoperative Nausea and Vomiting
Study type: Interventional

Summary: 
      Keyhole surgery for bowel disease has brought great benefits, enabling patients to recover
      quicker from surgery and so return to normal activities. Although keyhole surgery reduces
      pain following abdominal surgery, it still causes enough pain to require strong pain killing
      medications such as morphine-like drugs which, although good pain killers, can have a
      detrimental effect on the recovery of bowel function, leading to feelings of nausea and
      vomiting and ultimately delaying recovery. These side-effects can reduce the potential
      benefits from keyhole surgery and our "fast-track" recovery programmes.

      The aim of this project is to assess the effectiveness of a new method of pain control after
      keyhole bowel surgery. The study involves the injection of local anaesthetic into the
      abdominal muscles once the patient is anaesthetised. Although use of local anaesthetic is
      common practice, we are looking at a new technique of injecting it called a transversus
      abdominis plane (or TAP) block. This technique will attempt to block the pain nerves to the
      abdomen prior to the operation beginning. We plan to investigate whether this new technique
      will reduce the amount of pain following keyhole bowel surgery. If successful, it might be
      used to further enhance people's recovery from bowel surgery.
    

Detailed description: 
      A considerable component of post-operative pain following abdominal surgery arises from the
      anterior abdominal wall. Although laparoscopic surgery has been shown to reduce
      post-operative pain scores compared to open surgery, there is still the problem of abdominal
      pain arising, in particular, from the specimen extraction site. Commonly used regimes to
      counter this pain include intravenous opiate-based patient-controlled analgesia (PCA) pumps,
      although such drugs can have a detrimental effect on the post-operative recovery of bowel
      function and leads to an increased risk of post-operative nausea and vomiting (PONV). The
      consequence of these gastrointestinal complications is that the benefits to patients of
      laparoscopic surgery with enhanced recovery programmes are not fully realised.

      The benefits of adequate postoperative analgesia include a reduction in the postoperative
      stress response, reduction in postoperative morbidity, and in colorectal surgery, improved
      surgical outcome. Other benefits of effective regional analgesic techniques include reduced
      pain intensity, decrease incidence of side effects from analgesics (such as PONV), and
      improved patient comfort.

      The innervation of the anterior abdominal wall comes from nerve afferents from T6-L1 running
      in the neurovascular plane which is found between internal oblique and transversus abdominis
      (TA). The transversus abdominis plane (TAP) block aims to block these nerves with local
      anaesthetic before they pierce the anterior abdominal wall. It has already shown to be
      effective in reducing pain in the first 24 hours after a laparotomy when compared to PCA with
      opiates and shown to have potential in a series of patients undergoing radical prostatectomy.

      The potential improvement of this technique is weighed against the added risks of injecting
      into the neurovascular plane. There is a theoretical risk of a significant flank haematoma as
      a result of injury to the small vessels running with the nerves. In addition there is the
      small risk of inadvertent peritoneal puncture although the risk of any subsequent significant
      injury is very small and would likely be detected at the time of subsequent laparoscopy.
      Although there is one case report of a needle puncture to the liver due to previously unknown
      hepatomegaly, the injury was detected at laparotomy and the consequences were insignificant.

      Experimental Methods and Design Patients would be randomised to receive either 20mls of local
      anaesthetic on each side of the abdomen in the TA plane or to receive no additional
      treatment. Both groups would receive local anaesthetic into the wounds at the end of the
      procedure. The TAP block would take place after induction of anaesthesia but before
      commencement of surgery. The TAP block would be carried out in a standardised manner using
      ultrasound guidance by two experienced anaesthetists with considerable experience in this
      technique. For blinding purposes, the site of entry on the skin for a TAP block will be
      covered with a plaster, irrespective of whether a block has been given.

      A standardised anaesthetic and a standard post-operative analgesia regimen will be given to
      both groups.

      Patients will be withdrawn from analysis if a colorectal resection does not take place or the
      surgery is converted to an open procedure, although data will continue to be collected.
    

Intervention name(s): Levobupivicaine 0.25%
Intervention type(s): Drug
Intervention description(s): 40mls of 0.25% L-bupivicaine will be injected into the transversus abdominis plane (TAP) under ultrasound guidance - 20mls on either side of the abdomen.
Other intervention name(s): Chirocaine
Intervention MeSH terms: Levobupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Transversus abdominis plane block; Laparoscopic colorectal surgery; Analgesia