A comparison of the incidence of the oculocardiac and oculorespiratory reflexes during sevoflurane or halothane anesthesia for strabismus surgery in children.

UNLABELLED: We examined changes in the cardiorespiratory system of small children during surgical correction of strabismus with a laryngeal mask airway and spontaneous respiration with sevoflurane or halothane inhaled anesthesia. Fifty-one children, 1-7 yr old, having outpatient strabismus correction were randomized to sevoflurane (S) or halothane (H) in 66% nitrous oxide at 1.3 minimum alveolar concentration. Children breathed spontaneously through a laryngeal mask airway and were not pretreated with anticholinergics. The oculocardiac reflex (OCR), defined as a 20% decrease in heart rate (HR) from baseline, dysrhythmias, or sinoatrial arrest concomitant with ocular muscle traction occurred less frequently with sevoflurane than with halothane (S 38%, H79%, P = 0.009). The baseline HR was higher with sevoflurane (S 114 +/- 13 bpm, H 101 +/- 15 bpm, P = 0.002). The lowest HR occurred with halothane (S 95 +/- 22 bpm, H 73 +/- 19 bpm, P = 0.001). The incidence of dysrhythmias was higher in the halothane group (S 4%, H 42%, P = 0.004). Reductions in minute ventilation and PETCO(2) accompanied OCRs. Airway irritability was present with halothane only (S 0, H 3). Eleven children, of whom the majority had received halothane, required measures to correct SpO(2) < 95% or PETCO(2) > 60 mm Hg during maintenance anesthesia (S 11%, H 32%). Sevoflurane may be a more suitable anesthetic than halothane for operations involving traction on the ocular muscles with spontaneous respiration in children because of reduced incidence of OCR, airway irritability, and ventilatory disturbances. IMPLICATIONS: Some children experience a sudden slowing of the heart and impaired breathing when the surgeon pulls on the eye muscles during squint operations under anesthesia. Sevoflurane, a recently developed anesthetic vapor, may reduce this problem when compared with the established vapor halothane.

RCT Entities:   Population Interventions Outcomes