Evaluation of a TAP Block Given During Laparoscopic Colorectal Surgery to Help Control Pain

Overview

Patients experience pain after surgery mostly from their abdominal wounds, even when those wounds are small. Decreasing that pain has many benefits. It improves comfort, decreases stress response and might improve the outcome of the surgery. Local anesthesia (which is a numbing agent given directly at the site of pain via a needle) is given to decrease the pain that is felt after surgery and decrease the need for strong pain medications which can have negative side effects. One promising way to give local pain medication is called the "transversus abdominis plane" or TAP block. This method works by directly blocking the nerves in the abdomen that are the cause of the pain patients feel in their incision after surgery. This is done by injecting a numbing agent (Bupivacaine) into the area of their abdomen where their nerves are located that cause pain. In the case of nerves that carry sensation, bupivacaine blocks the pain sensation traveling in a particular nerve. Patients will be randomized (like a flip of a coin) to receive either a normal saline injection or the bupivacaine injection. The purpose of this study will be to prove the effectiveness of local anesthetic given via a TAP block in improving postoperative pain, decreasing the use of pain medications, decreasing postoperative nausea and vomiting and improve surgical outcomes such as hospital length of stay in laparoscopic colorectal surgery.

Using standard surgical procedures, the surgeon will proceed with the planned laparoscopic surgery. All procedures will be done by straight laparoscopic technique according to standard of care. At the completion of the procedure, and under laparoscopic control, patients will have a TAP block placed by the attending surgeon. The clinical research nurse involved in the research will prep the solution to be injected and the surgeon will be blinded as to whether the patient will be receiving normal saline or Marcaine in the TAP blocks. The block will be administered between the costal margin and iliac crest in the anterior axillary line. A Braun Stimuplex A insulated needle (80 mm 21 gauge) with 0.5 mL/kg solution (max of 30 ml) is passed through the skin, and then continued until two distinct "pops" are felt, which indicates the needle piercing each of the two fascial layers. The needle is then deemed to be in the inter-muscular plane between internal oblique and transversus abdominis muscles respectively, to target the spinal nerves in this plane. The laparoscope will be visualizing for the needle tip to ensure that it does not penetrate the peritoneum or inject pre-peritoneally. The local anesthetic is infiltrated in two separate injections into the same plane on each side. If a sub-peritoneal bleb is seen to be raised by the laparoscope, then the needle will be withdrawn slightly. Two thirds of the solution is injected, and the needle is withdrawn 5 mm and the remaining solution is injected. If injecting in the correct plane, then a smooth raised area of fluid, covered by transversus will be seen via the laparoscope. This procedure is repeated on the patients other side, to complete a bilateral block. Depending on their randomization, patients will receive one of the following solutions: Group A: Represents the control group and will receive 0.5 ml/kg of 0.9% normal saline for a maximum of 30 ml. Group B: Represents the experimental group and will receive 0.5 ml/kg of 0.25% Marcaine (bupivacaine) for a maximum of 30 ml.