Analgesic Effect of Ultrasound-Guided Bilateral Quadratus Lumborum Block (Lateral Approach) Versus Bilateral Transversus Abdominis Plane Block With General Anesthesia in Laparoscopic Abdominal Surgery (Randomized Controlled Clinical Trial)

This prospective randomized, observer-blinded paralleled groups study was conducted following the tents of the Declaration of Helsinki. This study was approved by the local institutional ethics committee and local institutional review board of Fayoum university hospital and written informed consent was obtained from 50 adult patients scheduled for elective laparoscopic abdominal surgical procedures (inguinal hernia repair-missed IUCD extraction-appendectomy-ovarian vein ligation) between July 2019 and February 2020.

Patients were randomly allocated into two groups (QLB group n=25 and TAPB group n=25) using computer generated random numbers kept in separate opaque envelopes that were opened by the study investigator just before the block. The patient and the data collector were unaware of the group allocation till the end of the study.

Pre-operative assessment (History, examination and investigations) was done (according to the local protocol designed to evaluate the patients). Demographic characteristics: age, weight, height and BMI were recorded in preoperative assessment of patients. All patients received 150 mg Ranitidine oral tablet at night and on the morning just before the operation as a premedication. Before surgery, the participants received education about the VAS pain score (0-10) (where 0 = no pain and 10 = worst comprehensible pain) and the details of the nerve block procedures. After a 6 hrs fasting, the patients were taken to the operation theatre.

Upon arrival to the operating room standard monitors (Pulse oximeter, noninvasive blood pressure monitoring, capnography and electrocardiogram) were applied and continued all over the operation, an 18 gauge peripheral intravenous (IV) cannula was inserted, IV midazolam 0.03 mgkg-1, metoclopramide 10 mg, and ceftriaxone 1 gm were administered to all patients as premedication then pre-oxygenation with O2 100% for at least 3 min then induction of anesthesia was done with fentanyl 1μgkg-1, propofol 1.5-2 mgkg-1 and atracurium 0.5 mgkg-1. Anesthesia was maintained by volume controlled ventilation (VCV) tidal volume 6-8 mlkg-1 with oxygen and air (50:50) with target of EtCO2≈ 35-40 mmHg, isoflurane 1:1.5 % volume concentration and atracurium 0.1 mgkg-1 every 20-30 minutes.

The study solution was prepared in two syringes each contained 20 ml of bupivacaine 0.25%. By the end of surgery and before recovery from general anesthesia, either blocks were done using a high-frequency ultrasound probe Active Array L12-4 (8-13MHz) of an ultrasound machine (Philips clear vue350, Philips healthcare, Andover MA01810, USA) and a 22-gauge, 50 mm echogenic needle (Stimuplex D; B Braun, Germany).