Effect of TAP Block on Stress Hormones
Condition: Abdominal Hysterectomy; Postoperative Pain
MeSH terms: Pain, Postoperative
Study type: Interventional
Phase: Phase 4

Summary: 
      Random allocation of patients in two groups; Tap block group (T group) and control group (C
      group). All patients will receive standard general anesthesia and postoperative pain
      management. The TAP group patient will receive ultrasound guided (US) TAP block with 20 cc of
      0.25% of bupivacaine and control group will receive 20cc of normal saline. TAP block in both
      groups will be performed with US guidance and the study drug will be injected after complete
      visualization of the needle tip between the internal oblique and the transversus abdominis
      muscles.

      Venous blood samples (5 ml for each time) for metabolic and stress hormones, including, Serum
      cortisol and nor-epinephrine will be collected before anesthesia at the time of cannulation
      (T1),60 minutes after incision(T2), 6hrs (T3)and 12 h (T4) after the surgery.

      Postoperatively patient will be put on patient controlled intravenous infusion of nalbuphine
    

Detailed description: 
      Total abdominal hysterectomy (TAH) is a commonly performed major surgical procedure that
      results in substantial postoperative pain and discomfort. It has been shown that surgical
      pain and trauma can lead to a number of hormonal changes initiated by the neuronal activation
      of the hypothalamic pituitary-adrenal axis and the sympathetic nervous system, which can have
      a detrimental effect on the patient. Strenuous effort has been made to inhibit the stress
      response to surgery and evaluate its outcome.

      It has been shown that this stress response is influenced by the mode of anesthesia and
      postoperative analgesia. A surgery induced stress response blunted by regional technique and
      the potential benefits of regional analgesia on surgical outcome are still under scrutiny.
      Among the postoperative analgesic technique, epidural analgesia has shown to significantly
      abolish the perioperative stress responses after number of surgeries including hysterectomy.
      In Pakistan only a small proportion of women wants to avail the epidural service due to fears
      and misconception.

      Another modality of regional technique that has gained popularity as a part of multimodal
      analgesia is transversus abdominis plane (TAP) block. It is a newly developed block involving
      the nerves of the anterior abdominal wall. The abdominal wall sensory afferents course
      through the transversus abdominis plane superficial to the transversus abdominis muscle. An
      important component of the pain experienced by patients after abdominal surgery derives from
      the abdominal wall incision.

      The efficacy of the TAP block in providing postoperative analgesia as a part of multimodal
      analgesia has been demonstrated in number of surgeries including colonic resection surgery,
      caesarean delivery, radical prostatectomy and also hysterectomy. In literature search
      investigators did not find any clinical study that has been carried out to see the effect of
      TAP block on stress response after hysterectomy. This study is designed to test the
      hypothesis that the TAP block, as part of a multimodal analgesic regimen, would attenuate
      stress response after TAH when compared with placebo. The investigators will also see any
      difference in postoperative pain and rescue analgesic demands and side effects among
      patients.

      Rationale for the study

      Background information:

      Failure to adequately control postoperative acute pain can have a number of unwanted
      physiological and psychosocial consequences for the patient including dissatisfaction,
      myocardial problems, prolonged hospital stay and even the potential progression to chronic
      pain. Pain associated with abdominal surgery can be very severe and can lead to a number of
      hormonal changes initiated by the neuronal activation of the hypothalamic pituitary-adrenal
      axis and the sympathetic nervous system, which can have a detrimental effect on the patient.

      Current postoperative analgesic regimens rely heavily on systemic opioid analgesics which are
      associated with a number of undesirable side effects including nausea, vomiting,
      constipation, respiratory depression, and many others. In addition developing countries like
      Pakistan have limited supply of good quality opioids ,thus safer alternatives need to be
      evaluated. As a result postoperative pain management in a developing country like Pakistan
      has been less than suboptimal and barriers include general lack of resources in terms of
      personnel, drug availability and basic equipment

      It has been observed that in developing countries only 45% of anesthetist had ready access to
      morphine and pethidine. Currently, the cost of importing morphine to developing countries is
      disproportionately high. A survey of opioid costs in 2003 showed that opioid drugs were up to
      10 times more expensive in the developing world than in the developed world, after adjustment
      for differences in gross domestic product. Therefore in order to find the alternatives; local
      anaesthetic techniques by means of regional analgesic technique can provide excellent
      postoperative pain relief and their use should be encouraged whenever possible. There is a
      need to find techniques to improve postoperative analgesia which will decrease the
      requirement for opioids, are safe, cost effective, easy to perform and acceptable to
      patients.

      TAP block a form of regional analgesia has been investigated as a part of multimodal
      analgesia and has shown promising result in decreasing the pain scores and opioid consumption
      but its role in inhibiting the surgical stress response is still not known. TAP block has
      been practiced at Aga Khan University hospital (AKUH) since 2012 now, but no data regarding
      its effect on stress hormones has been collected.

      Work has been done on epidural analgesia, which is also a type of regional technique and
      attenuation of stress hormones is seen by the investigators with this form of analgesia.
      Epidural analgesia is an invasive procedure, which is expensive and requires expertise and
      equipment. It is not routinely practiced in our part of the world due to the above mentioned
      reasons. Epidural analgesia is used at AKUH, but it often less acceptable to patients as it
      is performed near the spinal cord and also because of the cost related issue.

      Therefore the rational of this study is to observe, if a less expensive, easy to perform and
      safer form of regional analgesia like TAP block has an inhibitory effect on the surgical
      response or not. If favorable results are seen with TAP block, it can be incorporated in the
      practice guidelines of pain management for abdominal hysterectomies and related surgeries.

      Primary Objective

      This study is designed to test the hypothesis that the TAP block, as part of a multimodal
      analgesic regimen, would attenuate stress response after TAH when compared with placebo. An
      ultrasound (US)-guided TAP block will be performed before surgical incision.

      Venous blood samples (20 ml) for metabolic and stress hormones, including cortisol and
      norepinephrine will be collected before anesthesia (T1) at the time of cannulation, and 30
      minutes after incision(T2) 6hrs (T3)and 24 h (T4) after the surgery.

      Secondary Objectives The investigators will observe any difference in postoperative pain by
      numeric rating score (NRS) and rescue analgesic demands by the reading on patient controlled
      analgesia pump, total opioid consumption and side effects like nausea, vomiting, sedation by
      scoring them.

      Patient satisfaction score by scoring system
    

Intervention name(s): TAP Block with Bupivicaine; TAP Block with Placebo drug
Intervention type(s): Procedure; Procedure
Intervention description(s): Ultrasound guided TAP block will be performed and patient will be administered 20 ml of 0.25 % Bupivicaine on each side.; Ultrasound guided TAP block will be performed and patient will be administered 20 ml of 0.9% Saline on each side.
Intervention MeSH terms: Bupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Prospective double blind randomized control trial
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: transversus abdominis plane block; abdominal hysterectomy; stress response