Effectiveness of Unilateral Transversus Abdominis Plane (TAP) Block vs Bilateral TAP Block in Patients Undergoing Laparoscopic Cholecystectomy.

1. INTRODUCTION:

Laparoscopic cholecystectomy (LC) is the gold standard procedure for individuals with symptomatic gallstone disease. Although LC is a minimally invasive procedure with very less morbidity, early post-operative pain still a significant issue.1 Adequate pain control is therefore necessary to improve clinical outcomes, patient satisfaction and to ensure early mobility of the patients. Pain after laparoscopic cholecystectomy can be broadly classified into 3 categories: (a) somatic pain due to skin incisions; (b) Visceral pain due to intra-abdominal gallbladder dissection and; (c) reflected visceral pain or referred pain to the tip of right shoulder. Out of these, the somatic pain from port site incisions is the most troublesome for patients. Various methods have been tried to reduce post-operative pain after LC, one of which is the Transversus abdominis plane (TAP) block. TAP block is a regional anesthesia technique used for post-operative analgesia in abdominal surgeries. TAP block was first described by Rafi et al in 2001, as a regional block, in which local anesthesia is injected through triangle of petit to achieve analgesia of the T6 to L1 thoracolumbar nerves as they pass through the plane between internal oblique and transversus abdominis muscles.5,7,8 This blocks the sensory nerves in the anterolateral abdominal wall. Unilateral TAP block has been used as a part of multimodal analgesia in LC, with favorable results. However, half of the port site incisions in LC are located in the midline, i.e. the subxiphoid epigastric and the umblical ports. So, whether a unilateral TAP block alone provides adequate analgesia or not, cannot be stated as a fact. Although literature compares unilateral vs bilateral TAP in a variety of different surgical procedures, such as cesarean section and laparoscopic shockwave lithotripsy10,11 only one study is available to compare unilateral TAP versus bilateral TAP in LC.

Thus, the rationale of this study is that more research needs to be done to compare unilateral and bilateral TAP blocks in LC so as to establish which of the two is more efficient in providing adequate analgesia and eliminating the need for post-operative intravenous opioids. This will help us to better understand the role of in TAP block in LC. It is expected that this will help in reducing the need and dosage for postoperative IV opioids thus reducing post-operative nausea and vomiting (PONV), improve patient satisfaction and allow early mobilization of the patient. Mayo hospital Lahore is one of the largest government sector hospitals of Punjab with a dedicated surgical facility well equipped to deal with large numbers of patients with symptomatic gallstones. This makes this hospital an ideal set-up for conducting this research. 2. OBJECTIVE:

Primary objective of this study is to compare unilateral and bilateral TAP blocks in terms of efficacy in terms of mean duration of postoperative analgesia and the need and amount of post- operative IV opioids needed. Secondary objectives include comparison of both blocks in terms of PONV, the need and amount of ondensetron, and patient satisfaction. 3. OPERATIONAL DEFINITIONS:

1. TRANVERSUS ABDOMINIS PLANE (TAP) BLOCK:

Tap block is a regional block, where a local anesthetic is inserted into the triangle of petit in the plane between internal oblique and transversus abdominis muscles to block the neuronal afferents from T6-L1 spinal roots, which provide somatic supply to the anterolateral abdominal wall. 2. TRIANGLE OF PETIT:

An anatomical landmark in the posterolateral abdominal wall bounded anteriorly by the most posterior attachment of external oblique muscle, posteriorly by the most anterior attachment of lattismus dorsi muscle and inferiorly by the iliac crest. The floor of the triangle is formed by internal oblique muscle. 3. POST-OPERATIVE PAIN:

Post-operative pain is defined as the pain intensity reported by the patient following surgery, using the Visual Numerical Rating Scale (VNRS) at rest and after cough, assessed at predefined intervals. The VNRS is a numeric scale from 0 to 10, where 0 indicates no pain and 10 indicates the worst pain imaginable. 4. RESEARCH QUESTION:

Is right unilateral TAP block equally effective as a bilateral TAP block in terms of decreasing post- operative pain and need for IV opioids in patients undergoing laparoscopic cholecystectomy? 5. HYPOTHESIS:

Bilateral TAP block is more efficacious than a right unilateral TAP block in preventing postoperative pain and need of IV opioids in patients undergoing laparoscopic cholecystectomy. 6. NULL HYPOTHESIS:

There is no difference between a right unilateral TAP block and a bilateral TAP block in terms of post-operative pain and the need of IV opioids in patients undergoing laparoscopic cholecystectomy.

• Frequency of Postoperative nausea and vomiting (PONV) [Time frame: From the end of surgery to the end of treatment at 24 hours postoperatively]