A Comparison Between the Effects of Peribulbar and Sub-tenon Blocks Combined with General Anesthesia on the Incidence of Oculocardiac Reflex during Pediatric Strabismus Surgery: A Double-Blinded Randomized Control Study

Background: Pediatric strabismus surgeries have frequently been linked to the occurrence of oculocardiac reflex (OCR). This study aimed to assess the efficacy and safety of peribulbar and sub-tenon blocks on the occurrence of OCR during pediatric strabismus surgeries. Materials and Methods: A randomized, double-blinded trial was conducted with 120 children (ASA I/II) scheduled for strabismus surgery. Patients were randomized into three groups: control (intravenous paracetamol 15 mg/kg), sub-tenon (0.08 mL/kg of 0.5% bupivacaine), and peribulbar (0.25 mL/kg of a 1:1 mixture of 0.5% bupivacaine and 2% lidocaine). The study assessed the incidence rate of OCR as well as the time of occurrence of OCR after induction, hemodynamic variables, postoperative pain and analgesic requirements, the incidence of postoperative vomiting (POV), complications resulting from the orbital regional anesthesia, and total intraoperative atropine requirements. Results: The OCR incidence did not differ significantly between groups. Twenty-three patients (57%) in the sub-tenon group, 14 patients (35%) in the peribulbar group, and 14 patients (35%) in the control group experienced OCR (P 0.063 and 0.201). All OCR cases were treated with atropine. Pain scores at 4 h post-surgery were significantly higher in the sub-tenon and peribulbar groups compared to the control group (P 0.001 and 0.041, respectively). The sub-tenon group had one case of POV, whereas the control group had five cases (P 0.025). Conclusion: Both sub-tenon and peribulbar blocks effectively reduced POV and analgesic requirements in pediatric strabismus surgery, but did not prevent the occurrence of OCR. Keywords: Anesthetic, oculocardiac reflex, pediatric, postoperative pain, strabismus