This prospective, randomized controlled comparative study was conducted at Ain Shams University Hospital from December 2019 to July 2020. After approval of the Research Ethics Committee of Ain Shams University in December 2019, the study was registered at https://clinicaltrials.gov/ct2/show/NCT04215705. Eighty adult patients aged 21-60 years; both American Society of Anesthesia (ASA) physical status I and II, scheduled for PCNL surgery were invited to enroll in this study.
Preoperative clinical assessment for all patients and laboratory investigations (e.g CBC, liver and kidney function tests, coagulation profile). Patients with bleeding disorders, allergies to local anesthetics, psychiatric disorders, and those who refused to share in the study were excluded. The anesthesia plan and VAS score were discussed with the patient. All data were documented and signed a formal consent were obtained from all participants.
Participants were randomly divided preoperatively into two equal groups using computer generated table, placing them in a sealed envelope and then opening the envelope in the OR. The first group (Q) received ultrasound guided Quadratus Lumborum Block III, the second group (P) received fluoroscopic guided Peritubal Local Infiltration.
All patients received general anesthesia (GA), standard monitoring include ECG, NIBP, ETCO2, SPO2 were applied, General anesthesia was induced with Propfol (2mg/kg), fentanyl (1ug/ kg) Atracurium (0.5mg/kg) then oral endotracheal intubation with cotrolled mechanical ventilation was performed. Patients positioned into prone position with protection of pressure points. GA was maintained with isoflurane 1 MAC in an oxygen/ air mixture 50%: 50% and atracurium 0.1mg/kg every 20 minutes. All patients received Granisetron (1 mg) slowly IV.
At the end of the surgery, In Group (Q) patients were placed in the semi-lateral position so that the related kidney was in an upside position for the Quadratus Lumborum block which was performed by one of the primary investigators. A broadband (5–2 MHz) curved array transducer (sonosite M-Turbo®) was used, and the probe was positioned in an anterosuperior trajectory at the level of the iliac crest and moved upward toward the abdominal wall until the three muscles of the anterior abdominal wall were defined clearly. The hook sign was identified by visualizing the posterior border of the external oblique muscle, leaving below the internal oblique muscle, and over the Quadratus Lumborum muscle. A hyperechoic line appears by tilting the probe caudally this line represents the intermediate layer of thoracolumber fascia. A 21-gauge 4-inch Stimuplex A needle; (B. Braun Medical Inc., Melsungen, Germany) was introduced in plane from anterior to posterior by hydrodissection at the fascial plane between the QL and Psoas muscle with injection of 20 ml of 0.25% bupivacaine on in the same side of PCNL.
In group (L), while patients were still in the prone position, a spinal needle 22-gauge 2-inch Stimuplex A needle; (B. Braun Medical Inc) was inserted by the urologist under fluoroscopic guidance along the nephrostomy tube till renal capsule was contacted in the 6 and 12 o’clock positions around it. A total of 20 ml bupivacaine 0.25% was infiltrated along the renal capsule, muscle, subcutaneous tissue, and the skin.
In both groups patients were turned to the supine position, and recovery from GA was performed by cessation of inhaled isoflorane and administration of 2.5 mg neostigmine and 1 mg atropine to antagonize the action of the muscle relaxant. Extubation was performed after fulfillment of the needed criteria, and the patient was moved to the postanesthetic care unit (PACU).
The postoperative analgesic strategy included 1-gram paracetamol given before extubation, which was repeated every six hours postoperatively, Additionally, patients were given IV ketorolac tromethamine 30 mg every 8 hours starting immediately after surgery. Patients in both groups were connected to a PCA machine containing morphine with a bolus dose of 1 mg boluses, lockout interval 6 min with no basal rate, and maximum 30 mg/24 h. Patient was instructed to use PCA for VAS≥5
Our study end point was designed as any participant who developed acute postoperative bleeding that necessitated surgical intervention or the occurrence of unexpected LA toxicity signs (e.g. arrhythmias, tinnitus, convulsions) that would be treated promptly according to the local hospital guidelines.
Measured parameters
Postoperative pain was assessed as the primary outcome both at rest and during movement or cough (dynamic) by an independent observer who was blinded to the procedure to avoid detection biases. The Visual analog scale (VAS) was used with a scale from 0 to 10, where 0 means no pain and 10 means unbearable pain, and it was measured at 2, 4, 6, 12, and 24 hours postoperative. Other variables were recorded as a secondary outcome, such as total morphine consumption during the first postoperative 24 hours, pain free interval till the first time rescue analgesia was needed, occurrence of complications of Quadratus Lumborum block (e.g. hypotension, and /or lower limb weakness) and patient satisfaction score.
Statistical Analysis
The collected data were organized, tabulated and statistically analyzed using SPSS software statistical computer package version 22 (SPSS Inc, USA). Shapiro-Wilk test was used as test of normality. Numerical variables such as age, BMI, surgery duration, anesthesia duration, stone size and first time to request analgesics 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 significant. Linear mixed models were used to account for repeated measures of VAS scores. A fixed effect model was used for the group, and a random effect model was used to adjust for repeated measures over time. The time-to-event variables were 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.
The primary outcome of this study was the postoperative pain visual analogue score measured after both techniques using G* power computer program version 3.1.9.2 was used to calculate the sample size required with 80% power, an alpha error of 0.05 and allocation ratio of 1. A sample size of at least 37 patients was calculated per group to achieve 80% power to detect an effect size of 0.8 (large effect size). To compensate for drop outs the sample size was increased to 40 patients in each group.