Effect of different anaesthetic regimes on the oculocardiac reflex during paediatric strabismus surgery

The oculocardiac reflex (OCR) is induced by mechanical stimulation and therefore is frequently encountered during strabismus surgery. This study was designed to determine how various anaesthetic regimes modulate the haemodynamic effects of the OCR during paediatric strabismus surgery. Thirty‐nine patients (4–14 years, ASA I) were randomized to one of four anaesthetic regimes: group P: propofol (12 mg·kg–1·h–1) and alfentanil (0.04 mg·kg–1·h–1); group S: sevoflurane 1–1.2 MAC in 30% O2/70% N2O; group K: ketamine racemate (10–12 mg·kg–1·h–1) and midazolam (0.3–0.6 mg·kg–1·h–1; group H: halothane 1–1.2 MAC in 30% O2/70% N2O. Electrocardiogram (ECG), beat‐to‐beat heart rate (HR) and blood pressure (BP) changes were measured during and after a standardized traction was applied to an external eye muscle (4–6 Newton, 90 s). OCR was defined as a 10% change in HR induced by traction. OCR occurred in 77% of patients. Whereas virtually all patients in the P, H and S groups developed OCR, only 22% developed it in group K. Median HR change in group P (–37 bpm) was significantly greater (P