Aerosol delivery in neonatal ventilator circuits: a rabbit lung model

Pediatr Pulmonol. 1991;10(3):208-13. doi: 10.1002/ppul.1950100314.


The benefits of inhaled therapy in ventilated neonates are recognized, but the reliability of drug delivery in nebulizer-ventilator circuits is uncertain. We quantified the effect of changing variables. Twenty-three freshly killed rabbits (1.15-1.9 kg) were ventilated via a tracheostomy by a pressure-limited, time-cycled ventilator (Neovent). A radioaerosol of 99Tcm pertechnetate from an Ultravent nebulizer (Mallinkrodt) was fed into the proximal ventilator tubing. Two 3-minute nebulizations at "standard settings" were followed by 2 at altered pressure, frequency, gas flow, I:E ratio, or position of the nebulizer in the circuit. Each nebulization was followed by a 3-minute gamma camera image and total deposited radioactivity was measured in excised lungs and trachea. Images demonstrated good peripheral aerosol deposition. At standard settings, lung deposition averaged 2.8% of the aerosol released. This was decreased markedly by reducing tidal volume (ventilator pressures) and residence time of aerosol (I:E ratio). Reduced gas flow decreased deposition slightly, presumably by increased particle size and marginally reduced tidal volume. Deposition did not change with increased frequency; increased minute ventilation was offset by decreased residence time of the aerosol. We conclude that the Ultravent nebulizer can be used to nebulize drugs in a standard neonatal circuit, although the dose delivered is small. Tidal volume and aerosol residence time are important determinants of aerosol delivery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bronchopulmonary Dysplasia / physiopathology
  • Bronchopulmonary Dysplasia / therapy
  • Disease Models, Animal
  • Humans
  • Infant, Newborn
  • Lung / diagnostic imaging
  • Lung / physiopathology*
  • Lung Compliance / drug effects
  • Lung Diseases / physiopathology*
  • Lung Diseases / therapy
  • Nebulizers and Vaporizers*
  • Plethysmography
  • Rabbits
  • Radionuclide Imaging
  • Respiration, Artificial* / methods
  • Sodium Pertechnetate Tc 99m / administration & dosage
  • Sodium Pertechnetate Tc 99m / analysis
  • Tidal Volume / drug effects


  • Sodium Pertechnetate Tc 99m