• Kitty Leung, Christopher J L Newth, Justin C Hotz, Kevin C O'Brien, James B Fink, and Allan L Coates.
• 1Physiology and Experimental Medicine Program of the Research Institute of The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. 2Departments of Anesthesiology and Critical Care Medicine and Respiratory Therapy, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA. 3Department of Respiratory Therapy, Rush University, Chicago, IL.
• Pediatr Crit Care Me. 2016 Apr 1; 17 (4): e177-81.

ObjectivesThe Vapotherm system delivers high humidity to the airway of patients by using semipermeable tubules where heated liquid water is in contact with air. The humidified air is conducted to the patient via a heated tube. Preliminary clinical observations in infants with croup suggested that epinephrine added to the water supplying the humidity was delivered successfully in the vapor phase. The purpose of this study was to evaluate the efficiency of the delivery of epinephrine in the vapor phase and to develop the feasibility criteria for a clinical pilot study.DesignThirty milligrams of epinephrine in a 1-L bag of sterile water was used as the humidification source for a Vapotherm 2000i. The output of the heated circuit was condensed and collected into a small Erlenmeyer flask via a metal coil while the whole collection system was submerged in an ice slurry to maintain the outflow temperature from the flask between 0°C and 2°C. The in vitro system was tested at 40°C with flows of 5, 10, and 15 L/min and L-epinephrine concentrations of 15, 30, and 60 mg/L. Each test was duplicated at each of the six conditions.SettingAcademic children's hospital research laboratory.PatientsNone.InterventionsNone.Measurements And Main ResultsThe system recovered more than 90% of the water vapor from the fully saturated air at 40°C. The epinephrine concentration recovery quantified by ultraviolet-visible spectrophotometry was 23.9% (27.5-20.4%) (mean and range) of the initial concentration. At flows of 5, 10, and 15 L/min, the delivery of epinephrine would be 1.8, 3.6, and 4.2 μg/min, respectively, which is in the therapeutic range used for parenteral infusion in young children.ConclusionsThe Vapotherm system can be used to deliver epinephrine in pharmacological doses to the respiratory system as a vapor and thus as an alternative to droplets by conventional nebulization.

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