Hemodynamic responses and plasma phenylephrine concentrations associated with intranasal phenylephrine in children

Abstract

Introduction: Intranasal phenylephrine, an alpha-1 adrenergic agonist, causes vasoconstriction of the nasal mucosa and is used to reduce bleeding associated with nasotracheal intubation or endoscopic sinus surgery. The purpose of this study was to describe the hemodynamic effects associated with plasma phenylephrine concentrations following topical intranasal administration of 0.25% and 0.5% phenylephrine in children.

Methods: After Institutional Review Board and parental approval, 77 children between the ages of 2 and 12 years were studied in a prospective, double-blind manner and randomized into three groups. Group 1 received intranasal saline, while groups 2 and 3 received 0.1 mL/kg of 0.25% or 0.5% phenylephrine, respectively. All received the same anesthetic of halothane, N₂ O, O₂ , and vecuronium. After inhalation induction, endtidal halothane and PaCO₂ were maintained at 1.5% and 35 mm Hg, respectively. Heart rate and rhythm, systolic, diastolic, and mean, noninvasive arterial blood pressures were recorded and venous blood was obtained for measurement of plasma phenylephrine concentration by high-performance liquid chromatography at baseline and at 2, 5, 10, and 20 minutes following intranasal spray application of the study drug. Nasotracheal intubation was performed immediately following the 5-minute measurements, and the presence of bleeding was assessed. Hemodynamic data were compared by analysis of variance for repeated measures. Bleeding and arrhythmia incidence among groups were analyzed using chi-squared tests. Phenylephrine levels were correlated with hemodynamic values via regression analysis.

Results: Fifty-two patients received intranasal phenylephrine. Increases in blood pressure correlated with increasing plasma phenylephrine concentration. Systolic blood pressure increased 8%, and mean blood pressure increased 14%, which were statistically significant but clinically insignificant. Heart rate did not change, and the incidence of arrhythmia was low and similar among groups. Bleeding following nasotracheal intubation was less frequent in Group 3 (11/27 subjects) than in Group 1 (17/25). Peak plasma phenylephrine concentrations were observed by 14±7 minutes following intranasal administration, and were highly variable among individuals (37.8±39.7 and 49.6±93.9 ng/mL [mean±SD] in Groups 2 and 3).

Discussion: Administration of intranasal phenylephrine, 0.25% and 0.50%, results in rapid but highly variable systemic absorption that is associated with mild increases of blood pressure that are clinically insignificant. Bleeding associated with nasotracheal intubation was less following administration of 0.5% intranasal phenylephrine than following intranasal saline.

Keywords: blood pressure; intranasal phenylephrine; nasotracheal intubation; pharmacodynamics.