title: Placement of the nebulizer before the humidifier during mechanical ventilation: Effect on aerosol delivery.
abstract: BACKGROUND
  Therapeutic aerosols are commonly used in mechanically ventilated patients. The position of the nebulizer in the ventilator circuit and the humidification of inhaled gases can influence the efficiency of aerosol delivery. We evaluated the effect of nebulizer position on the pulmonary bioavailability of nebulized ipratropium in ventilated patients without known preexisting respiratory disease.
  
  
  METHODS
  The study included 38 mechanically ventilated and sedated patients after open heart surgery. Ipratropium (500 microg) was delivered by an ultrasonic nebulizer. Patients were randomized into 2 groups: the nebulizer positioned before the heat humidification system (group 1, n = 19) or at the end of the inspiratory limb before the Y-piece (group 2, n = 19). The amount of ipratropium in the urine collected during the 4 hours after drug administration was measured by mass spectrometry.
  
  
  RESULTS
  There were no statistically significant differences in tidal volume or respiratory rate between groups. There were no significant differences between the 2 groups in the amount of drug excreted (group 1 vs 2: 13,237 +/- 2313 pg/mL vs 15,529 +/- 3204 pg/mL) or in pulmonary bioavailability (.9% +/- .1% vs 1.1% +/- .2%).
  
  
  CONCLUSIONS
  The position of the nebulizer in the ventilatory circuit had no effect on the pulmonary bioavailability of ipratropium.
authors.affiliation: Department of Intensive Care, Erasme Hospital, Free Universite' libre de Bruxelles, Belgium.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Moraine
authors.forename: Karine
authors.initials: K
authors.lastname: Truflandier
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vandenbergen
authors.forename: Jacques
authors.initials: J
authors.lastname: Berré
authors.forename: Christian
authors.initials: C
authors.lastname: Mélot
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Vincent
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000336:Aerosols; D000368:Aged; D001682:Biological Availability; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D006348:Cardiac Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D006813:Humidity; D009241:Ipratropium / Q000627:therapeutic use*; D008168:Lung / Q000187:drug effects*; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D009330:Nebulizers and Vaporizers; D012121:Respiration, Artificial / Q000379:methods*
chemical_list: D000336:Aerosols; D001993:Bronchodilator Agents; D009241:Ipratropium