The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

A MATHEMATICAL MODEL FOR ACHIEVING TARGET LUNG DOSE OF PROSTACYCLINS.

Patricia A. Dailey1, Karthik Raghunathan1, Ploypan Thongpradit1, Kyle Walsh1, James Fink2; 1Respiratory Care, Baystate Medical Center, Springfield, MA; 2Division of Respiratory Therapy, Georgia State University, Atlanta, GA

Over the last 15 years, administration of Inhaled epoprostenol sodium has been reported, for the treatment of hypoxemia and pulmonary hypertension, during mechanical ventilation for both infants and adults. Dosing range is typically described as between 10 - 50 ng/kg/min based on formulation concentration and nebulizer output rate, independent of type of nebulizer used, and other factors impacting inhaled dose. Our goal is to quantify lung delivery based on aerosol delivery efficiency, leading to development of a tool to allow clinicians to determine required formulation strength, infusion rate and nebulizer output to achieve desired lung dose based on the efficiency of aerosol delivery system used. Methods: To better understand the relationship of nebulizer output to inhaled lung dose, we reviewed clinical reports of dosing strategies for epoprostenol and in vitro studies describing lung dose efficiency during mechanical ventilation with various aerosol devices, ranging from infants to adults. Lung dose was calculated by multiplying nominal output rate by the efficiency fraction of inhaled dose. We then developed a calculation to determine output rate required to reach target lung dose. Infusion rate in mL/hour = [(Target lung dose) x (BW in kg) x (1/Efficiency fraction) x (60)] / (formulation concentration in ng/mL) Results: Deposition efficiency fraction reported of 1 to 14% in neonates and 3 - 28% in adults resulted in calculated delivered lung doses ranging from 0.5 – 7ng/min for a 1 kg infant and 120 – 1,120 ng/min for an 80 kg adult. Conclusions: Adjusting key parameters to achieve target lung dose based on in vitro aerosol efficiency fraction, patient size, formulation concentration and aerosol output per hour provides opportunity for more precise dosing than standard systems based solely on concentration and a set nebulizer output per hour. Clinical trials will be required to confirm impact of this algorithm on inhaled dose titration. Sponsored Research - None Infusion Rates for a Target Lung Dose of 7 ng/kg/min Table shows infusion rates with a 30 mcg/ml formulation of epoprostenol sodium (1.5 mg in 50 cc sterile diluent) to achieve a target lung dose of 7 ng/kg/min with aerosol delivery efficiencies of 3%, 14% and 28% for an 80 kg and 15 kg patient.