The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

THE EFFECT OF AEROSOL DRUG DELIVERY ON AIRWAY RESISTANCE THROUGH HEAT-MOISTURE EXCHANGERS (HME): AN IN VITRO MODEL

Matthew Hart, Arzu Ari, Robert Harwood, Lynda Goodfellow, Meryl Sheard, James B. Fink; Georgia State University, Atlanta, GA

Background: The impact of aerosol generators placed between Heat Moisture Exchanger (HME) and endotracheal tube (ETT) on resistance has not been reported. The purpose of this study is to determine the effects of aerosol drug delivery on resistance through HMEs. Method: A ventilator (Respironics Esprit, Respironics Inc.) delivered adult parameters (Vt 500 mL, frequency 15/min, PEF:60 L/min, PEEP 5 cmH2O and I:E ratio 1:3) through an HME (Hyrgobac S, Tyco Healthcare) and 8.0 mm ETT to a heated humidifier simulating exhaled humidity (37 C and 100% RH) and test lung. Airway resistance of HME was determined through the ventilator with humidity alone at 5 min intervals for 45 min (placebo), and after 15 min with humidity followed by 6 standard doses of albuterol sulfate (2.5 mg/3 mL) via jet nebulizer (JN; Salter Labs), vibrating mesh (VM) nebulizer (Aeroneb Solo; Aerogen Inc.) or 6 puffs of albuterol via pMDI (ProAir HFA, Teva Pharmaceuticals) and spacer (Minispacer, Thayer Medical). All tests repeated in triplicate (n=3). ANOVA with post-hoc multiple comparisons were performed (p<0.05). Results: The resistance in cmH2O/L/sec (mean ± SD) with the pMDI, JN and VM nebulizer presented in the table below. Resistance with placebo from 15 – 45 min ranged from 9.1 to 9.26. A linear relation between number of treatments and airway resistance was observed with each type of aerosol generators. pMDI increased resistance above placebo at treatment 6 (p<0.05). JN and VM were greater than placebo after dose 1. Resistance was greatest with VM. Conclusion: Placement of aerosol devices between the HME and ETT increased airway resistance up to 35%. Caution should be exercised when operating nebulizers in this position. Sponsored Research - None

* Significantly different from pMDI (p < 0.05),

¥ Significantly different from pMDI and JN (p<0.05)

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