Comparison of sub-Tenon's block with i.v. fentanyl for paediatric vitreoretinal surgery

Background. Vitreoretinal (VR) surgery is associated with moderate to severe pain and significant postoperative nausea and vomiting (PONV). The study aimed to assess the effectiveness of sub-Tenon's block for providing perioperative analgesia in children undergoing VR surgery. Methods. In a randomized, observer-blinded trial, after obtaining institutional ethical committee approval and parental consent, 200 ASA grade I-II children aged 5-16 yr were allocated to receive either a sub-Tenon's block (Group SB) or 2 mu g kg(-1) i.v. fentanyl (Group F) after induction of anaesthesia and topical anaesthesia of the conjunctiva with proparacaine 0.5% drops. Patients in Group F received fentanyl 0.5 mu g kg(-1) and those in Group SB were given a corresponding volume of normal saline i.v. every hour from preloaded syringes. Increases in heart rate or mean arterial pressure by more than 20% of baseline were treated with additional 0.5 mu g kg(-1) i.v. fentanyl boluses in both groups. The incidence of oculocardiac reflex (OCR), need for additional analgesics, postoperative pain, and PONV were recorded for the first 24 h after surgery. Results. More patients in Group F (47.96%) had moderate to severe pain in the first 24 h when compared with Group SB (31.36%) (P=0.023). The need for postoperative ibuprofen was higher in Group F (66.3%) compared with Group SB (47.95%) (P=0.012). The incidence of OCR was significantly higher in Group F (31.6%) compared with Group SB (5.1%) (P<0.001). The incidence of PONV was similar in both groups. Conclusions. Sub-Tenon's block provides more effective analgesia than i.v. fentanyl for paediatric VR surgery.