Background and Goal of Study: Postoperative nausea and vomiting (PONV) is one of the most common complications after strabismus surgery under general anesthesia. Although mechanisms of PONV after strabismus surgery are not still clearly understood, traction on extraocular muscles (EOM) as well as drugs used for general anesthesia is the known triggering factor of PONV. This prospective, randomized, double blinded study was designed to compare the prophylactic effect of ondansetron and ramosetron on PONV after strabismus surgery under general anesthesia. The secondary purpose was to investigate if the number of involved EOM in the strabismus surgery was related to PONV.
Materials and Methods: In total, 105 patients (aged 16-60) undergoing strabismus surgery were enrolled and randomly allocated to one of the three groups, placebo, ondansetron, or ramosetron group. Each of the three groups was subdivided into two groups regarding the number of extraocular muscle involved in the surgery: group S, single-muscle correction; group M, multiple muscle correction.
General anesthesia was induced with 2 mg/kg propofol and 0.6 mg/kg rocuronium. After tracheal intubation, anesthesia was maintained with 1.5-2 vol% sevoflurane, medical air in oxygen (fraction of inspired O2 [FiO2] = 0.5), and continuously infused IV remifentanil 2-3 ng/ml. Patients received placebo 2ml, ondansetron 4mg, or ramosetron 0.3mg at the end of surgery. The incidence of nausea or vomiting, and patients' satisfaction were recorded at 2 h, 24 h, and 48 h after surgery.
Results and Discussion: The incidence of nausea was significantly lower in ramosetron group at 2 h (9.4%) and 24 h (3.1%) after surgery than was in placebo and ondasetron group (p = 0.033 and 0.029, respectively).
Patients in ramosetron group were more satisfied with the antiemetic therapy at 2 h (7.88 ± 0.98) and 24 h (8.50 ± 0.67) after the surgery than those in placebo (6.84 ± 1.34, 7.45 ± 1.29, respectively at 2 h and 24 h) and ondansetron group (6.85 ± 1.83, 7.27 ± 1.59, respectively at 2 h and 24 h) (p < 0.05). When comparing S and M group in each group, there were no significant intra-group differences in incidence of nausea and use of rescue antiemetics, and satisfaction of patients.
Conclusion(s): Ramosetron has superior anti-emetic effect to ondansetron after strabismus surgery in adults. The number of EOM involved in strabismus surgery was not in association with the incidence of PONV.