Laparoscopic TAP Block for Sleeve Gastrectomy: Does Timing Matter

This is a single blinded, prospective study designed to determine optimal timing of transverse abdominis plane block (TAP block) in laparoscopic gastric sleeve patients. Research has shown that administration of TAP block during these cases does show improved post-operative pain control. There are no trials specifically evaluating the timing of administration in regards to superiority of pain control. To the investigators knowledge, no prospective study has ever been done investigating whether TAP block performed at the beginning of the case versus at the end of the case makes a difference in the amount of relief experienced by the patient. the investigators hypothesize that early intra-operative block will be superior to late intra-operative block in both post-operative pain as well as decreased length of stay in hospital secondary to reduction in peripheral and central nervous system hyper excitability. Before beginning the research study, ~200 plain envelopes will be made each containing one option written on paper indicating early intra-operative or late intra-operative TAP block. There will be equal numbers of both options. It will be the responsibility of either the PI or sub-investigators to select a random envelope and bring it to the operating room at the time of surgery. All patients involved in the study will have given informed consent in the office prior to surgery. On the day of surgery after the patient is induced and intubated, the PI or sub-investigator will open the envelope revealing the timing of the TAP block. Depending on what is revealed from the envelope, the patient will either receive the early intra-operative TAP block or the late intra-operative TAP block. The TAP block will be performed using 60 ml for right sided TAP block (side of specimen extraction) and 30 ml for left sided TAP block (non extraction side). 30 ml of bupivicaine solution will also be used for intraperitoneal irrigation as is already routinely done during these cases by the primary surgeon for additional analgesia. This will be performed at the conclusion of all cases regardless of which arm the patient is in. For the early intra-operative TAP block, optiview trocar entrance will be performed in the upper abdomen followed by CO2 insufflation. After introduction of the camera into this trocar, the right lateral abdominal wall will be visualized with the laparoscope. An 18-gauge needle will be introduced externally at the center of the mid axillary line between the lower costal margin and the iliac crest until the surgeon feels a "pop," after which the surgeon will inject the first 2 mL of 0.25% bupivicaine to verify the correct position. Doyle's internal bulge sign (the bulge seen when the transversus abdominis muscle and peritoneum is pushed internally) will be visualized and the remainder of the 60 mL of 0.25% bupivacaine will be injected. The contralateral block will be performed according to the same technique but with only 30 ml of bupivicaine. The late post-operative block will be performed in the same fashion but after completion of the surgery just prior to removing the trocars and desufflation. The intraperitoneal irrigation with 0.25% bupivicaine solution will be performed at the end of the case using 30 ml total sprayed above the stomach, under the diaphragm, and over the bed of the spleen. All other medications intra-op and post-op including anesthesia will remain standardized according to the current HF Macomb bariatrics protocols. The data collection will take place immediately post-op, 4, 8, 12, 16, 20, and 24 hours post-op using the numerical assessment score (NAS) for pain which will be performed at the time vitals are taken by the nursing aids. The investigators will also be analyzing post-operative vomiting and length of stay in hours.