Clinical Impact of Specific Extraocular Muscle Manipulation and the Oculocardiac Reflex on Postoperative Vomiting in Pediatric Strabismus Surgery: A Multicenter, Observational Study.

Background: Strabismus surgery, which is commonly performed in children, poses a high risk of postoperative vomiting. The current anesthesia guidelines for the prevention of postoperative vomiting in children are based on heterogeneous populations involving different types of surgery, and risk factors for postoperative vomiting in, specifically, the pediatric strabismus surgery population are unclear. Moreover, the effects of manipulating the deeply attached extraocular muscles and the oculocardiac reflex on this risk remain inconclusive.

Aim: To evaluate the associations among inferior oblique muscle manipulation, the oculocardiac reflex, and postoperative vomiting in children with retrospectively collected data.

Methods: The study had a multicenter retrospective cross-sectional design and was conducted at three institutions (two tertiary-care children's hospitals and one pediatric-adult mixed community hospital). It included children aged < 18 years and without major comorbidities undergoing strabismus surgery. The primary exposure was inferior oblique muscle manipulation during surgery. The outcome of interest was postoperative vomiting or antiemetic medication usage within 24 h postsurgery or by discharge.

Results: Among 3152 children postoperative vomiting occurred in 108/795 (13.6%) children with and 227/2357 (9.6%) without inferior oblique muscle manipulation (unadjusted odds ratio, 1.57; 95% confidence interval, 1.21-2.05; p = 0.001). Multilevel logistic regression analysis, adjusting for potential confounders and surgeon-related variance, revealed that inferior oblique muscle manipulation (adjusted odds ratio, 1.58; 95% confidence interval, 1.15-2.18; p = 0.005), but not the oculocardiac reflex (adjusted odds ratio, 1.06; 95% confidence interval, 0.76-1.48; p = 0.73), was associated with postoperative vomiting after adjusting for confounders.

Conclusions: Stronger preventive measures against postoperative vomiting are recommended in healthy children undergoing strabismus surgery with inferior oblique muscle manipulation. Additionally, inferior oblique muscle manipulation should be considered a potential confounder in future related studies. However, the oculocardiac reflex was not associated with postoperative vomiting in pediatric strabismus surgery.