The application of dexmedetomidine in children undergoing vitreoretinal surgery

Abstract

Dexmedetomidine is a highly selective alpha-2 adrenergic agonist that has a sedative effect and has been shown to reduce anesthetic requirements. It also has a sympatholytic effect, which may prove useful when used to blunt the sympathetic surge during intubation and extubation. However, its effects on intraocular pressure, hemodynamic stability, attenuation of extubation response, and emergence agitation remain unclear for pediatric patients undergoing vitreoretinal surgery. We focused on these effects in this study. Sixty ASA I-II patients undergoing vitreoretinal surgery, were anesthetized with sevoflurane 1-2% end-tidal concentration in oxygen supplemented by remifentanil 0.2μg/kg/min. Intraocular pressure was measured after inhalation of sevoflurane (IOP(Baseline)) and 10min after intravenous administration of dexmedetomidine 0.5μg/kg or normal saline (IOP(10min)), after induction of anesthesia. Blood pressure and heart rate were recorded every 5min during surgery. The incidence and severity of coughing and emergence agitation and untoward airway events after extubation, for example breath holding, laryngospasm, bronchospasm, and oxygen desaturation, were assessed. Extubation time and emergence time were also documented. There was no significant difference in intraocular pressure at the two time points between the groups (p>0.05). In both groups mean arterial pressure and heart rate decreased from baseline after anesthetic induction (p<0.05). The increase from intraoperative values in mean arterial pressure and heart rate associated with extubation was diminished in the dexmedetomidine group compared with the control group (p<0.05). Coughing after extubation was less common (10 vs. 21) and less severe (3 moderate and 7 minimal; vs. 2 severe, 7 moderate and 12 minimal) in the dexmedetomidine group than in the control group (p<0.05). There were no significant differences between the groups in time to emergence or extubation (p>0.05). The dexmedetomidine group had a lower incidence of emergence agitation than the control group (10 vs. 43.3%, p<0.05). The incidence of breath holding, laryngospasm, bronchospasm and oxygen desaturation was not significantly different between the groups (p>0.05). Dexmedetomidine 0.5µg/kg had no effect on intraoperative hemodynamics or intraocular pressure, but attenuated the hemodynamic response to extubation and diminished emergence agitation in pediatric patients undergoing vitreoretinal surgery.