The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts


Michael Luethge1, Nicholas Haglund2, Michael Duryee2, Carlos Hunter2; 1Respiratory Care Services, The Nebraska Medical Center, Omaha, NE; 2University of Nebraska Medical Center, Omaha, NE

BACKGROUND: Administration of intravenous (IV) Milrinone is commonly used in patients to manage cardiac ventricular dysfunction, low cardiac output, and increased pulmonary vascular resistance (PVR) following cardiac surgery. Systemic hypotension can occur at IV Milrinone dosages which achieve maximum PVR dilation. In an effort to minimize the systemic hypotension side effects, a pre-clinical trial bench evaluation of inhaled aerosolized Milrinone was performed. METHODS: Milrinone (0.5mg/ml) was introduced into a vibrating-mesh nebulizer from a syringe pump set at two infusion rates, 12ml/hr (Sample A) and 6ml/hr (Sample B). Three 30 minute tests were performed at two pump infusion rates. The nebulizer was added to the dry-side of a humidifier column on a 72” dual-heated adult ventilator circuit, connected to a standard dual chamber test lung via an 8.0mm endo-tracheal tube (ETT). Between the test lung and the end of the ETT, two viral/bacteria filters were inserted in series to collect nebulized Milrinone precipitate. Ventilator settings were FiO2 0.60, PRVC mode, rate - 12, TV - 500ml, IT - 1.0, PEEP 5 cmH20, Rise time 0.15 seconds and compliance compensation ON. The compliance setting on the Michigan instruments test lung was 0.06 ml/cmH2O with resistor number 3 in use. The Milrinone was extracted from the 12 filters using a methanol bath and concentration was determined by High-Performance Liquid Chromatography (HPLC). RESULTS: As shown in the table, the average amount of Milrinone collected on the filter proximal to the breathing circuit Y-piece for samples A and B were 477.2mcg and 216.1mcg, respectively. The total percentage of Milrinone recovered on the filter at the end of the ETT was 15.74% for Sample A and 14.41% for Sample B. Milrinone was not recovered on the second filter in any of tests (distal to the breathing circuit Y-piece). CONCLUSION: Consistent concentrations of nebulized Milrinone were delivered to the end of an ETT using the apparatus described. The percentage of nebulized Milrinone (0.5gm/ml) available at the end of an ETT for deposition and absorption by the lung is consistent with other routine aerosolized inhaled medications (Ari A., Respiratory Care, 2010). The total amount of Milrinone administered via the vibrating-mesh nebulizer is dependent on the set infusion rate of the pump. Further clinical trials are needed to determine the safety and efficacy of nebulized Milrinone. Sponsored Research - None