Comparison of two concentrations (0.125% and 0.25%) of bupivacaine for ultrasound guided sacral erector spinae block in paediatric patients undergoing hypospadias repair: A double blind randomised trial.

Background and Aims: The volume and concentration of local anaesthetic are particularly importance for the success of a block in providing analgesia. To improve safety, the goal should be the minimum dose of local anaesthetic capable of providing maximum effectiveness. Interfascial plane blocks are considered volume blocks, and a higher volume of local anaesthetic needs to be injected into the fascial plane to achieve the desired effect. Reducing the local anaesthetic concentration may limit the total dose administered without changing the volume injected. Material and Methods: Sixty children aged 8-12 years undergoing hypospadias repair were included in the study. After the induction of general anaesthesia, Group I (n = 30) was given an ultrasound-guided sacral erector spinae block with 1 ml/kg of 0.125% bupivacaine, and Group II (n = 30) received the same block with 1 ml/kg of 0.25% bupivacaine. Postoperatively, when the visual analogue scale (VAS) score was ≥ 4, rescue analgesia was administered using intravenous paracetamol at 15 mg/kg. The primary objective was to compare the time to the first paracetamol rescue. Secondary objectives included intraoperative hemodynamic parameters, additional fentanyl consumption, postoperative visual analogue scores, and total analgesic consumption (paracetamol and ibuprofen) within 24 h. Results: The mean time to the first paracetamol rescue was 20.0 h (standard deviation [SD]: 3) h in Group I and 22.5 h (SD: 3) h in Group II (P = 0.19) (mean difference 2.5 [95% CI: -6.46, 1.46]), with a Cohen's d value of 0.83. The postoperative VAS scores at different time points were similar between the two groups. Ibuprofen was not required by any patient. The mean postoperative analgesic consumption (paracetamol) was 385 mg (SD: 77.85) in Group I and 427.5 mg (SD: 31.22) in Group II (P = 0.32) (mean difference 42.5 [95% CI: 16.08, 89.96]), with a Cohen's d value of 0.71. Conclusions: Bupivacaine 0.125% is as effective as 0.25% bupivacaine in terms of the time to first paracetamol rescue for sacral erector spinae block in paediatric patients undergoing hypospadias repair.