After the approval of the Institute Ethics Committee (INT/IEC/2021/SPL-514) PGIMER Chandigarh, this randomized controlled double-blind trial was conducted in eligible voluntary kidney donors belonging to American Society of Anesthesiologists (ASA) physical status 1 and 2, aged 18 years or older, and underwent LLDN under general anesthesia from March 2021 to August 2022. Participants with a local infection at the block site, allergy to local anesthetic agents, poor ultrasound window for ESPB, and refusal to consent to participate in the study were excluded from this study. This study was prospectively registered (CTRI/2021/07/045909) in the Clinical Trial Registry of India and followed the principles of the Declaration of Helsinki. A Written informed was obtained from all the study participants before enrolment in the study.
Group allocation and Blinding:
The study participants were randomized into two groups using a computer-generated random number: Group B and Group C. Group B received ultrasound-guided bilateral ESPB after surgery and before extubation at the T9-10 level in lateral position. Group C received general anesthesia along with local wound infiltration with bupivacaine 0.125% 15ml total volume (maximum dose 2 mg/kg) before extubation. Participants were blinded to their group allocation and the anesthesiologist who followed up with them postoperatively was also unaware of their group allocation.
Anaesthesia technique:
All the study participants were evaluated a day prior by the attending anesthesia team. They were informed of the procedure and the VNRS for pain (0 to 10, with 0 representing no pain and 10 representing the worst pain). Participants were instructed to follow standard fasting guidelines and were advised to take oral ranitidine 150 mg and alprazolam 0.25 mg tablets the night before and two hours before surgery. Participants in both the groups underwent LLDN under general anaesthesia. Anaesthesia was induced with intravenous fentanyl 2-5µg/kg followed by intravenous propofol 2 mg/kg. Atracurium 0.5 mg/kg was used to facilitate endotracheal intubation. Anaesthesia was maintained with 50% air-oxygen mixture and isoflurane (minimum alveolar concentration [MAC] 1-1.3) with the patient on positive pressure mechanical ventilation to maintain end-tidal carbon dioxide (EtCO2) between 32-36 mm of Hg. Fentanyl bolus of 1–2 μg/kg was intermittently administered to maintain the mean arterial blood pressure and heart rate within 20% of the baseline value.
Intervention:
In group B, under aseptic precautions, ultrasound-guided bilateral ESPB was performed at the end of surgery while the participants were in the lateral position at T9-10 vertebral level. A high-frequency linear ultrasound probe (5-10 MHz) (Sonosite, Inc. Bothell. WA 98021 USA) was placed 3 cm lateral to the spinous process in the sagittal plane. After identifying the hyperechoic transverse process, the paraspinal muscles were visualized. A 9 cm 20 G Quinke’s spinal needle was advanced until its tip was located between the transverse process and the erector spinae muscle. The correct tip location was confirmed by plane hydro-dissection with normal saline. Bupivacaine 0.125% (20 ml on the side of surgery and 10 ml on the contralateral side) was then administered in this plane between the erector spinae muscle and the vertebrae transverse process.
Intravenous Ondansetron 0.1 mg/kg and paracetamol 15 mg/kg were given at the end of surgery. Neuromuscular blockade was reversed using intravenous neostigmine (50 µg/kg) and glycopyrrolate (10 µg/kg) and the participants were extubated. Participants were then transferred to the postoperative recovery unit. If participants report a VNRS exceeding 4/10, intravenous morphine 3mg was administered. The following were recorded at different time intervals (Baseline, 0.5, 1, 2, 4, 6, 8, 12 and 24 hours): pain scores (VNRS), time to first rescue analgesia, and incidence and severity of PONV as per 4-point PONV scale (0- none, 1- mild nausea, 2- severe nausea, 3-vomiting episodes).
Statistical Methods:
Data were analyzed using International Business Machine (IBM) Statistical Package for the Social Sciences (SPSS) version 25.0 computer software and Microsoft Excel 2015. Data were presented as mean with standard deviation (± SD) or median with interquartile range (IQR). Normality was assessed using the Kolmogorov–Smirnov test. For normally distributed continuous data, Student’s t-test was used, and for categorical variables with two categories, the chi-squared (χ2) test was applied. The 24-hour cumulative median morphine consumption was compared using Mann-Whitney U test. Time to first rescue analgesia was analyzed using Kaplan Meier survival analysis. Postoperative resting and dynamic VNRS [median (IQR)] were analyzed using Mann-Whitney U test. This study had a 95% confidence interval and a p-value of less than 0.05 was considered statistically significant. A minimum of 30 participants in each group was required assuming that this would allow the detection of ≥ 30% difference in the postoperative morphine requirements for first 24 hours postoperatively with a power of 90% and alpha error of 0.05.