Lateral Quadratus Lumborum Block Versus Transversus Abdominis Plane Block in Laparoscopic Surgery
Condition: Abdominal Pain
MeSH terms: Abdominal Pain
Study type: Interventional

Summary: 
      The transversus abdominis plane (TAP) block is an already established technique and is
      considered now as an efficient part of the multimodal pain management approach for abdominal
      surgical procedures. The quadratus lumborum block (QLB) is a recently described regional
      block that was first described by Blanco et al , which has been reported to provide an
      effective analgesia for upper and lower abdominal surgeries. The aim of this study is to
      compare the analgesic efficacy of TAP block and QLB 1 after laparoscopic abdominal surgery
      regarding opioid consumption, duration of analgesia and visual analog score.

      This prospective randomized controlled observer-blinded study compared between the analgesic
      efficacy between TAP block (n=25) versus QL block (n=25) in patients aged (18-60) years of
      American society of anesthesiologists physical status class I & II scheduled for elective
      laparoscopic abdominal surgical procedures. The primary outcome was the cumulative morphine
      consumption at first 24 hours postoperatively. Secondary outcomes included VAS scores, first
      analgesic requirements and any postoperative complications
    

Detailed description: 
      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).

      For the ultrasound-guided quadratus lumborum block group, the patient was placed in lateral
      position and skin sterilization was done with povidone iodine. Then a high frequency linear
      probe was placed above the iliac crest to recognize the three layers of the abdominal wall
      muscles. Transversus abdominis was traced posteriorly until the transversus aponeurosis
      appeared, then the probe tilted slightly caudal to enhance the appearance of transversus
      aponeurosis. QL was identified medial to the aponeurosis of transversus abdominis muscle.
      Then the needle was inserted from supero-anterior to postero-inferior and advanced using in
      plane technique till the needle tip reached the anterolateral border of the QL at its
      junction with transversalis fascia. After negative aspiration (to exclude intravascular
      injection), the correct needle position was confirmed by hydrodissection using 1mL of normal
      saline. Then 20 mL of 0.25% bupivacaine was applied. The same technique was performed on the
      other side.

      For the ultrasound-guided TAP block, skin sterilization was done with povidone iodine. The
      probe was placed in the mid-axillary line above the level of the anterior superior iliac
      spine, then slided cranially till the three abdominal wall muscles identified (External
      oblique muscle (EAO), internal oblique muscle (IOM) and transverse abdominis muscle (TAM)).
      The needle was advanced using in-plane technique till it reached the transvers abdominis
      plane between the IOM and TAM, the correct needle position was proved by hydrodissection
      using 1 mL of normal saline. An injection of 20 mL of 0.25% bupivacaine was applied. The same
      technique was performed on the other side.

      After performing the block anesthesia was discontinued and tracheal extubation was done once
      the patient fulfilled the extubation criteria. Patients were transferred to post-anesthetic
      care unit (PACU), where they were discharged from the PACU after a modified Aldrete score≥9.
      Visual analogue scale (VAS) was used to assess postoperative pain. All patients received
      analgesics according to the local institutional protocol as following (paracetamol 1gm IV
      infusion/8 hrs and ketorolac 30 mg IM/12 hrs.). A postoperative rescue analgesia with
      morphine sulfate IV was given to patients with VAS >4 at a bolus dose of 3 mg increments with
      a maximum dose of 15mg per 4 hours or 45mg per 24 hours.

      Sample size was estimated using G*Power© software version 3.1.9.2 (Institute of experimental
      psychology, Heinrich Heine University, Dusseldorf, Germany)149 with total opioid consumption
      among the two groups as the main primary outcome. Previous similar researches150 demonstrated
      that the effect size between the two groups was expected to be large of 1.12 and it
      calculated that 42 patients (21 patients per group) would provide to achieve a power of 95%
      with type I error rate of 0.05. However, we assigned 50 patients (25 patients per group) to
      compensate for data loss. The collected data were organized, tabulated and statistically
      analyzed using SPSS software statistical computer package version 22 (SPSS Inc, USA). Data
      were tested for normality using shapiro-wilks test. Numerical variables such as age, body
      weight, height and BMI were normally distributed and were described as mean ± standard
      deviation (SD). An independent t-test was used to compare the mean values of the two groups.
      Other variables were not normally distributed and were presented as median and interquartile
      range (IQR); Mann-Whitney U test was used as a test of significance. The time-to-event
      variable (time to analgesic request) was evaluated using the Kaplan-Meier method, and the
      logrank test was used to compare the groups. Qualitative data were presented as numbers and
      percentages, and the chi-squared test was used to determine significance. A two-sided P-value
      of <0.05 was considered statistically significant.
    

Intervention name(s): Ultrasound guided QL block; Ultrasound guided TAP block
Intervention type(s): Procedure; Procedure
Intervention description(s): 20 mL of 0.25% bupivacaine was applied bilaterally at the anterolateral border of the QL at its junction with transversalis fascia; 20 mL of 0.25% bupivacaine was applied bilaterally in the TAP
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention
Keywords: laparoscopy; QL block; TAP block