Document Detail


Reconciling in vitro and in vivo measurements of aerosol delivery from a metered-dose inhaler during mechanical ventilation and defining efficiency-enhancing factors.
MedLine Citation:
PMID:  9872819     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We attempted to resolve the discrepancies in reported data on aerosol deposition from a chlorofluorocarbon (CFC)-propelled metered-dose inhaler (MDI) during mechanical ventilation, obtained by in vivo and in vitro methodologies. Albuterol delivery to the lower respiratory tract was decreased in a humidified versus a dry circuit (16.2 versus 30.4%, respectively; p < 0.01). In 10 mechanically ventilated patients, 4.8% of the nominal dose was exhaled. When the exhaled aerosol was subtracted from the in vitro delivery of 16.2% achieved in a humidified ventilator circuit, the resulting value (16.2 - 4.8 = 11.4%) was similar to in vivo estimates of aerosol deposition. Having reconciled in vitro with in vivo findings, we then evaluated factors influencing aerosol delivery. A lower inspiratory flow rate (40 versus 80 L/min; p < 0.001), a longer duty cycle (0.50 versus 0.25; p < 0.04), and a shorter interval between successive MDI actuations (15 versus 60 s; p < 0.02) increased aerosol delivery, whereas use of a hydrofluoroalkane (HFA)-propelled MDI decreased aerosol delivery compared with the CFC-propelled MDI. A MDI and actuator combination other than that designed by the manufacturer altered aerosol particle size and decreased drug delivery. In conclusion, aerosol delivery in an in vitro model accurately reflects in vivo delivery, providing a means for investigating methods to improve the efficiency of aerosol therapy during mechanical ventilation.
Authors:
J B Fink; R Dhand; J Grychowski; P J Fahey; M J Tobin
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  159     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1999 Jan 
Date Detail:
Created Date:  1999-02-11     Completed Date:  1999-02-11     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  63-8     Citation Subset:  AIM; IM    
Affiliation:
Division of Pulmonary and Critical Care Medicine, Hines Veterans Administration Hospital, and Loyola University of Chicago Stritch School of Medicine, Hines, Illinois, USA.
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MeSH Terms
Descriptor/Qualifier:
Aerosols*
Albuterol / administration & dosage
Bronchodilator Agents / administration & dosage
Chlorofluorocarbons
Drug Delivery Systems* / instrumentation
Equipment Design
Female
Humans
Humidity
Hydrocarbons, Fluorinated
Male
Particle Size
Pulmonary Ventilation / physiology
Respiration
Respiration, Artificial*
Chemical
Reg. No./Substance:
0/Aerosols; 0/Bronchodilator Agents; 0/Chlorofluorocarbons; 0/Hydrocarbons, Fluorinated; 18559-94-9/Albuterol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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