Randomized, Prospective, Study Comparing Four-quadrant Transverses Abdominis Plane (TAP) Block, Quadratus Lumborum (QL) Block and Surgeon Infiltration Using Exparel for Postoperative Analgesia After Laparoscopic Nephrectomy

Both four-quadrant TAP block and QL blocks will be done after induction of anesthesia but prior to incision. Surgeon infiltration will be completed intraoperatively at the end of the surgery. All procedures will be done using sterile technique with masks, hats, and sterile gloves. All procedures will be placed under the supervision of the attending anesthesiologist on the acute pain service.

All patients will receive 1 gm acetaminophen and 600 mg gabapentin preoperatively per SOC. Patients above 70 years will receive 300 mg gabapentin per SOC. Patients will be grouped by type of nephrectomy: simple, radical, or partial. Patients will be randomized to type of block. Intraoperatively, the patient will receive ketamine 0.5 mg/kg LBM at the beginning of the case followed by a 0.25 mg/kg/hr infusion during surgery but turned off prior to emergence per SOC; patients with relative contraindications to ketamine such as history of seizures may not receive ketamine and this will NOT be considered a deviation.

For group 1, the TAP block group, after the patient is induced, the skin will be prepped with ChloPrep and a clean, sterile transducer will be placed in an axial (transverse) plane to visualize the TAP plane just superior to the iliac crest. This will allow us to identify the three muscular layers of the abdominal wall: the external oblique (most superficial), the internal oblique, and the transversus abdominis. Using an in-plane technique (seeing the needle at all times), the needle will be advanced into the fascial plane between the internal oblique and transversus abdominis muscles under ultrasound guidance and 15 mL 0.125% bupivacaine plus 5 mL of Exparel® will be injected into the fascial plane; this procedure will be repeated in the other four quadrants of the abdomen. The tip of the needle will be observed under ultrasound at all times, making this a minimal risk procedure. It is also important to note that the mg dose of bupivacaine with exparel will never be in a ratio greater than 1:2 per Exparel dosing guidelines. A total of 80 mL will be given.

The QL block will be performed after induction with the patient placed in a slight lateral position in order to facilitate visualization of the Quadratus Lumborum muscle. Once the skin has been prepped and the sterile transducer is applied, the continuation of the transversalis fascia will be visualized along with the termination of the external and internal obliques. The quadratus lumborum will be identified deep to these structures. Once identified, an in plane technique will be used in order to place the needle in the plane just superior to the QL and 20 mL of 0.125% bupivacaine along with 10mL of Exparel will be injected. The same process will be repeated on the contralateral side. Once again the needle will be visualized throughout the procedure.

Surgeon infiltration will be completed at the end of the procedure before the patient emerges from general anesthesia. The needle will be inserted approximately 0.5 to 1 cm into the tissue plane to ensure that all layers of the surgical incision are infiltrated. The local anesthetic solution of 5 mL 0.125% bupivacaine plus 10 mL Exparel® will be injected while slowly withdrawing the needle to decrease the risk of intravascular injection.22 A total of 30 mL will be delivered. Surgeon name will be recorded.