Abdominal Surgery, Midline Laparotomy, Postoperative Pain
Conditions
Keywords
Quadratus Lumborum Block, Transversus Abdominis Plane Block, Ultrasound-Guided Regional Anesthesia, Postoperative Analgesia, Midline Laparotomy, Multimodal Analgesia
Brief summary
This randomized controlled trial compares the analgesic efficacy of ultrasound-guided bilateral lateral quadratus lumborum block (QLB, QL1) versus ultrasound-guided bilateral transversus abdominis plane (TAP) block in adults undergoing elective midline laparotomy under general anesthesia. The primary focus is postoperative pain intensity, time to first rescue analgesia, proportion requiring rescue analgesia, and total opioid consumption in the first 24 hours.
Detailed description
Midline laparotomy is associated with significant postoperative pain that can limit mobilization, impair respiratory function, and increase opioid-related side effects. Abdominal wall blocks such as the transversus abdominis plane (TAP) block and quadratus lumborum block (QLB) are used as part of multimodal analgesia. TAP primarily targets somatic afferents of the anterior abdominal wall, while QLB may provide broader coverage including potential paravertebral spread via the thoracolumbar fascia, potentially offering longer-lasting analgesia. This single-center, prospective, randomized controlled trial will enroll 100 adults (50 per group) aged 18-65 years, ASA physical status I-III, scheduled for elective midline laparotomy under general anesthesia. Participants will be randomized 1:1 using sequentially numbered, opaque, sealed envelopes prepared by an independent research assistant. Both blocks will be performed after induction of general anesthesia and before surgical incision by an experienced anesthesiologist under ultrasound guidance and strict aseptic precautions. Group A (QLB): Bilateral lateral quadratus lumborum (QL1) block with 20 mL of 0.25% bupivacaine per side (total 40 mL / 100 mg, not exceeding 2 mg/kg). Group B (TAP): Bilateral TAP block with 20 mL of 0.25% bupivacaine per side (total 40 mL / 100 mg, not exceeding 2 mg/kg). Postoperative analgesia will be standardized with intravenous paracetamol 1 g every 6 hours. Pain will be assessed using the Numerical Rating Scale (NRS 0-10) at 6, 12, and 24 hours by an independent, blinded outcome assessor. Rescue analgesia (intravenous morphine or tramadol) will be given for NRS ≥4. Primary and secondary analgesic outcomes include NRS scores, time to first rescue analgesia, proportion requiring rescue analgesia within 24 hours, and total opioid consumption in the first 24 hours. Block-related complications will also be recorded. Statistical analysis will use SPSS version 26. Normality will be assessed by Shapiro-Wilk test. Continuous variables will be compared with independent-samples t-test or Mann-Whitney U test; categorical variables with Chi-square or Fisher's exact test. Potential confounders will be addressed by stratification. A two-sided p-value ≤0.05 will be considered statistically significant.
Interventions
PROCEDUREUltrasound-Guided Lateral Quadratus Lumborum Block (QL1)
After induction of general anesthesia and before surgical incision, under strict aseptic precautions, a low-frequency curvilinear ultrasound transducer is placed between the costal margin and iliac crest. An echogenic 22-gauge 80-100 mm block needle is advanced in-plane toward the anterolateral border of the quadratus lumborum muscle near the junction of the transversus abdominis aponeurosis and transversalis fascia. After hydrodissection and negative aspiration, 20 mL of 0.25% bupivacaine is injected on each side under continuous ultrasound visualization of local anesthetic spread. Total planned volume 40 mL (100 mg bupivacaine), not exceeding 2 mg/kg.
After induction of general anesthesia and before surgical incision, under strict aseptic precautions, a high-frequency linear ultrasound transducer is placed transversely on the anterolateral abdominal wall between the costal margin and iliac crest. The external oblique, internal oblique, and transversus abdominis muscles are identified. An echogenic 22-gauge block needle is advanced in-plane until the tip lies in the fascial plane between the internal oblique and transversus abdominis muscles. After hydrodissection and negative aspiration, 20 mL of 0.25% bupivacaine is injected on each side under continuous ultrasound visualization of local anesthetic spread. Total planned volume 40 mL (100 mg bupivacaine), not exceeding 2 mg/kg.
DRUGBupivacaine 0.25%
Local anesthetic used for both QLB and TAP blocks: 20 mL of 0.25% bupivacaine per side (total 40 mL / 100 mg), dose adjusted not to exceed 2 mg/kg body weight.
Sponsors
Sheikh Zayed Medical College
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
Patients will remain blinded to group allocation because both blocks are performed after induction of general anesthesia. The anesthesiologist administering the block cannot be blinded. Postoperative pain assessment and outcome recording will be performed by an independent outcome assessor who remains blinded to group allocation.
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-65 years * Either sex * Scheduled for elective midline laparotomy (upper, lower, or full midline incision) under general anesthesia * ASA physical status I-III
Exclusion criteria
* Body mass index \>40 kg/m² * Existing chronic pain disorder, established opioid dependence, or history of substance abuse * Previous or current neurological or psychiatric illness likely to compromise comprehension, decision-making capacity, or reliable reporting of pain scores * Conditions in which an abdominal wall block would not be appropriate or safe (bleeding tendency, ongoing anticoagulation outside acceptable limits, local skin or soft-tissue infection at the planned puncture site, or major distortion of abdominal wall anatomy) * Urgent laparotomy performed for peritonitis or unstable physiology (including patients requiring continuous vasopressor support) * Previous abdominal wall surgery, large incisional hernia, or distorted flank/anterior abdominal wall anatomy likely to impair standardized block placement
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Postoperative pain intensity at 12 hours | 12 hours after completion of surgery | Pain intensity measured using the Numerical Rating Scale (NRS; 0 = no pain, 10 = worst imaginable pain) assessed by an independent blinded outcome assessor. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Postoperative pain intensity at 6 hours | 6 hours after completion of surgery | Pain intensity measured using the Numerical Rating Scale (NRS 0-10) by an independent blinded outcome assessor. |
| Postoperative pain intensity at 24 hours | 24 hours after completion of surgery | Pain intensity measured using the Numerical Rating Scale (NRS 0-10) by an independent blinded outcome assessor. |
| Time to first rescue analgesia | From completion of surgery up to 24 hours postoperatively | Time (in minutes or hours) from completion of surgery to the first administration of rescue analgesia for NRS score ≥4. |
| Proportion of participants requiring rescue analgesia within 24 hours | First 24 hours after surgery | Percentage of participants who receive at least one dose of rescue analgesia (for NRS ≥4) within the first 24 postoperative hours. |
| Total opioid/rescue analgesic consumption within 24 hours | First 24 hours after surgery | Cumulative dose of opioid or rescue analgesic administered within the first 24 postoperative hours, recorded from the medication administration record. |
| Incidence of block-related complications | During block performance and within 24 hours after the block | Any complication considered related to QLB or TAP block (e.g., local anesthetic systemic toxicity, hematoma, infection, nerve injury, block failure). |
Countries
Pakistan
Contacts
CONTACTKiran Azhar, MBBS
PRINCIPAL_INVESTIGATORKiran Azhar, MBBS, FCPS-II (Anesthesia) PGR
Department of Anesthesiology & ICU, Sheikh Zayed Medical College/Hospital, Rahim Yar Khan
STUDY_CHAIRSairah Sadaf, FCPS
Department of Anesthesiology & ICU, Sheikh Zayed Medical College/Hospital, Rahim Yar Khan
Outcome results
None listed