Epinephrine-halothane interactions in children

Cutaneous infiltration of dilute solutions of epinephrine for hemostasis during halothane anesthesia can result in ventricular dysrhythmias. Our clinical experience, published reports, and a study comparing piglets with adult swine suggest that children may be less susceptible than adults to dysrhythmias under these conditions. We therefore undertook a prospective survey of heart rate and rhythm in halothane-anesthesized children who received subcutaneous epinephrine for hemostasis. Mass spectrometry was used to quantify end-tidal halothane and to avoid hypercarbia. In 83 children anesthesized with halothane, we continuously recorded ECG, heart rate (HR), end-tidal halothane (ETHalo), and carbon dioxide (ETCO2). The surgeons injected 0.4--15.7 micrograms/kg of epinephrine (in saline or 1% lidocaine) to provide hemostasis at a variety of sites. No child developed a ventricular dysrhythmia. One child had self-limited premature atrial contractions (PAC). Sixty-three children had some increase in heart rate after epinephrine injection, while seven increased their HR 15% or more above pre-injection levels. No relation between any increase in HR and epinephrine dosage, ETHalo, ETCO2, physical status, or age was found by multiple linear regression; however, HR was increased significantly in patients receiving epinephrine in head and neck sites other than the palate. The authors conclude that children tolerate higher doses of subcutaneous epinephrine than adults during halothane anesthesia. The arrhythmogenic dose of epinephrine in children receiving halothane has yet to be determined, but at least 10 micrograms/kg of epinephrine infiltration may be used safely in normocarbic and hypocarbic pediatric patients without congenital heart disease. The presence of PAC and tachycardia emphasize the need for continuous ECG monitoring and caution during halothane anesthesia with epinephrine injection.