Albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model

Crit Care Med. 1996 May;24(5):870-4. doi: 10.1097/00003246-199605000-00023.


Objectives: To assess albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model and to determine the influence of the following variables on albuterol delivery: endotracheal tube diameter; type of spacer; humidification; and pulmonary mechanics.

Design: Prospective, in vitro, laboratory study.

Setting: Research laboratory.

Interventions: A model, consisting of a volume-cycled ventilator, pediatric breathing circuit, 4.0- or 6.0-mm endotracheal tube, and lung simulator, was assembled. Ventilator settings were: tidal volume 250 mL; FIO2 0.5; inspiration/expiration ratio 1:3; respiratory rate 25 breaths/min; positive end-expiratory pressure 3 cm H2O; temperature 35 degrees C; and a decelerating flow pattern, using dry and humidified air. Lung simulator compliance and resistance values were consistent with those values reported for healthy childeren (20 mL/cm H2O and 40 cm H20/L/sec) and children with pulmonary disease (10 mL/cm H2O and 60 cm H2O/L/sec). Pulmonary mechanics were verified with a pulmonary function diagnostic system. Ten metered-dose inhaler canisters were used to administer 2000 micrograms of albuterol, using either a collapsible or a rigid spacer. A circuit filter placed immediately proximal to the test lung collected drug exiting the endotracheal tube. The filter was rinsed with water and albuterol concentrations were determined by high-performance liquid chromatography. Each variable was tested in triplicate.

Measurements and main results: Albuterol delivery was significantly (p < or = .05) greater for the 6.0-mm endotracheal tube, rigid spacer, dry air, and pulmonary disease mechanics by multifactor analysis of variance. Drug delivery in humidified air with pulmonary disease mechanics using the rigid chamber was 2.5 =/- 0.27% and 6.3 =/- 0.99% for the 4.0- and 6.0-mm endotracheal tubes, respectively.

Conclusions: These in vitro results suggest that pulmonary disease mechanics and a 6.0-mm endotracheal tube improve albuterol delivery. Future clinical investigations in intubated pediatric patients with pulmonary disease are needed to address the clinical significance of these results.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Albuterol / administration & dosage*
  • Asthma / drug therapy*
  • Asthma / physiopathology
  • Bronchodilator Agents / administration & dosage*
  • Child
  • Disease Models, Animal
  • Drug Delivery Systems / instrumentation*
  • Drug Evaluation, Preclinical
  • Humans
  • Nebulizers and Vaporizers*
  • Prospective Studies
  • Respiration, Artificial / instrumentation
  • Respiration, Artificial / methods*
  • Respiratory Mechanics


  • Bronchodilator Agents
  • Albuterol