RT Journal Article
SR Electronic
T1 In Vitro Evaluation of Radiolabeled Aerosol Delivery via a Variable Flow Infant CPAP System
JF Respiratory Care
FD American Association for Respiratory Care
SP respcare.01904
DO 10.4187/respcare.01904
A1 Kimberly D Farney
A1 Brandon T Kuehne
A1 Laurie A Gibson
A1 Leif D Nelin
A1 Edward G Shepherd
YR 2013
UL http://rc.rcjournal.com/content/early/2013/08/06/respcare.01904.abstract
AB Background: Nasal Continuous Positive Airway Pressure (NCPAP) is widely used in neonatal intensive care units. Aerosolized medications such as inhaled steroids and beta-agonists are commonly administered in-line through NCPAP, especially to infants with bronchopulmonary dysplasia (BPD). We hypothesized that aerosol delivery to the lungs via variable flow NCPAP in an in vitro model is unreliable, and such delivery depends on the position of the aerosol generator within the NCPAP circuit. Methods: We used a system that employed a test lung placed in a plastic jar subjected to negative pressure. Simulated inspiration effort was measured by use of a heated wire anemometer. We used TC 99mTc-DTPA as our aerosol. The nebulizer was placed either close to the humidifier (position A) or close to the nasal prongs (position B) in the circuit and patient effort was simulated at a 0.4 L/min minute-ventilation. Results: Relative aerosol delivery to the infant test lung using position A was extremely low (0.3 ± 0.4%); while position B resulted in significantly (p<0.001) improved delivery (21 ± 11%). Major areas of aerosol deposition in position A vs. B were: nebulizer (10 ± 4% vs. 33 ± 13%; p<0.001), exhalation limb (9 ± 17% vs. 26 ± 30%; p=0.23), and generator tubing (21 ± 11% vs. 19 ± 20%; p=0.86). Position A resulted in 59 ± 8% of the aerosol being deposited in the inhalation tubing along the heater wire. Conclusions: Isotope delivery from a generator placed near the humidifier on variable flow NCPAP is negligible in this in vitro setup; however such delivery was significantly improved by locating the aerosol generator closer to the NCPAP interface.