Effect of Ice Slush on Reducing the Oculocardiac Reflex During Strabismus Surgery.

Abstract

The aim of this study was to explore whether ice slush (IS) causing local hypothermia can effectively inhibit the oculocardiac reflex (OCR) during strabismus surgery. This prospective, randomized, double-blind study included 58 patients with concomitant strabismus scheduled for lateral rectus (LR) recession under general anesthesia. Patients were randomly allocated to receive IS (IS group) or standard treatment (control group) with sterile saline at room temperature before surgery. OCR was defined as a sudden decrease in heart rate (HR) of >15% from baseline. If one incidence of the OCR was found in 1 patient in any stage (0/I/II/III), the patient was defined as an OCR responder, and the incidence of overall OCR was the incidence of OCR responders. The primary outcome was the incidence of overall OCR during all stages of the surgery, which was analyzed by the Z test and computed based on the absolute risk difference with 2-sided 95% confidence intervals (CIs) using the Newcombe method. The overall OCR occurred in 19 of 29 patients (62.5% [95% CI, 45.7-82.1]) in the IS group and 28 of 29 patients (96.6% [95% CI, 82.2-99.9]) in the control group (absolute risk difference, -31.0% [95% CI, -49.4 to -11.0]; Z test, P < .001), which demonstrated that the incidence of overall OCR in IS group was significantly lower than that in the control group. IS on the ocular surface causing local hypothermia is a promising and easily accessible method to reduce the overall OCR, which can improve the safety of strabismus surgery.