The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts

COMPARISONS OF THE RAM CANNULA WITH HIGH FLOW NASAL CANNULA (HFNC) ON AEROSOL DRUG DELIVERY IN A SIMULATED NEONATAL LUNG MODEL.

Arzu Ari1, Robert Harwood1, Hui-Lin Ling2, Robert DiBlasi3, William Callas4, Meryl Sheard1, Debbie Gilley4, Tracey Roberts4, Vickie Arnolde4, James Fink1; 1Division of Respiratory Therapy, Georgia State University, Atlanta, GA; 2Chang Gung University, Tao Yuan, Taiwan; 3Seattle Children’s Research Institute, Seattle, WA; 4Lucile Packard Children’s Hospital at Stanford, Palo Alto, CA

Background: Aerosol delivery through HFNC has been described with in vitro models. The RAM cannula, which is used for support of ventilator-dependent patients, has not been characterized for aerosol delivery. The purpose of this study is to compare HFNC with RAM cannula on aerosol drug delivery in a simulated neonatal lung model. Method: An in-vitro airway/lung model, using the DiBlasi newborn upper airway model attached to a collecting filter and test lung, was passively ventilated with a ventilator (Respironics Esprit) using the RAM cannula (Premie RAM Cannula, Neotech) or during active simulated spontaneously breathing newborns using a sinusoidal breathing pump with a HFNC (Fisher& Paykel) placed in the nares of the model. Based on the RAM manufacturer’s recommendations, two ventilator settings were utilized with the RAM cannula; PIP 15 cmH2O, PEEP 5 cmH2O, Ti 0.5 sec, RR 40/min; and PIP 30 cmH2O, PEEP 8 cmH2O, Ti 1 sec, RR 48/min. Breathing parameters used with HFNC include RR 50, Vt 8ml, and I:E ratio 1:2. A vibrating mesh nebulizer (Aeroneb Solo, Aerogen) was placed at the inspiratory inlet of a heated humidifier (Fisher&Paykel) in which the temperature was held constant at 37 °C. Albuterol sulfate (2.5mg/3mL) was administered through either HFNC and the RAM cannula connected to the HFNC and ventilator circuit, respectively. Drug deposited on a filter distal to the model’s trachea was eluted and analyzed via spectrophotometry. Independent and paired sample t-test were used for data analysis (p < 0.05). Results: Deposition of inhaled dose (expressed as mean mass and % of nominal dose ± SD) is shown in the table below. Comparisons of the RAM cannula with HFNC showed that the RAM cannula delivers significantly less aerosols than HFNC at both 3 lpm (p=0.002) and 6 lpm (p=0.022). Using minimum setting with the RAM cannula increases dose efficiency (p=0.033) during mechanical ventilation. Decreasing flow rate from 6 to 3 L/min increases aerosol delivery with HFNC (p=0.119). Conclusion: Regardless of the settings, aerosol delivery via HFNC is more efficient than the RAM cannula in a simulated neonatal lung model. Sponsored Research - None