The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

EFFECTS OF HEAT AND MOISTURE EXCHANGERS DESIGNED TO ALLOW AEROSOL DELIVERY ON AEROSOL DEPOSITION IN SIMULATED MECHANICALLY VENTILATED ADULTS.

William Bowers, Robert Harwood, James B. Fink, Meryl Sheard, Ralph Zimmerman, Arzu Ari; Division of Respiratory Therapy, Georgia State University, Atlanta, GA

BACKGROUND: Heat and moisture exchangers (HME) reduce aerosol deposition. Mechanisms to bypass the HME during aerosol delivery (HME-AD) have been introduced without supporting research evaluating their effectiveness. The purpose of this study was to determine the effect of HME-ADs on aerosol deposition in simulated mechanically ventilated adults. METHOD: A ventilator (Respironics Esprit, Respironics Inc.) delivered adult parameters (Vt 450 mL, frequency 20/min, PIF 50 L/min, PEEP 5 cmH2O and I:E ratio 1:2) through an HME-AD and 8.0 mm ETT to a heated humidifier simulating exhaled humidity (37 C and 100% RH) and test lung. The types of HME-ADs used in this study include: (1) Circuvent (Smiths-Medical, Keene, NH) with a standard HME, (2) Gibeck Humid-Flo HME (Hudson RCI, Arlington Heights, IL), and (3) Airlife BHME (Carefusion, San Diego, CA). Four separate doses of albuterol sulfate (2.5 mg/3mL) were nebulized using a vibrating mesh nebulizer (Aeroneb Solo, Aerogen, Ireland ) placed in the inspiratory limb with no HME (Control) and with each HME-AD with aerosol bypass open (Aerosol configuration) and closed (HME configuration). Each condition was repeated in triplicate (n=3). Drug was eluted from a filter distal to ETT and analyzed by spectrophotometry (276 nm) Student t-tests and ANOVA were performed at the significance level of 0.05 (p < 0.05). RESULTS: The table shows % of total albuterol dose inhaled (mean ±SD). In the aerosol configuration, all devices delivered less aerosol compared to the control, Circuvent and Humid-Flo were significantly different than the control (p=.004 and p=.002, respectively). Aerosol delivery in the HME configuration was higher than anticipated with 93.8% of aerosol for the Humidflo, (p=.078), 76.8% for the Airlife and 33.9% for the Circuvent (p=.002 and p=.005, respectively). CONCLUSIONS: Small differences on aerosol deposition between Aerosol and HME configurations suggest that some HME-AD do not effectively close the aerosol bypass feature when engaging the HME Sponsored Research - None