In vitro performance of spacers for aerosol delivery during adult mechanical ventilation

J Aerosol Med Pulm Drug Deliv. 2015 Apr;28(2):130-6. doi: 10.1089/jamp.2013.1091. Epub 2014 Jul 22.


Background: During mechanical ventilation, different aerosol generators are employed with various interfaces. The objective of this study was to evaluate the performance of a range of spacers, including a new device called Combihaler® designed for connection with both nebulizers and pressurized Metered-Dose Inhalers (pMDIs).

Methods: To assess the spacers, we used a ventilator and the Dual Adult Training and Test Lung (model 5600i, Michigan Instruments). Ventilation parameters were measured with and without spacers in volume-controlled and pressure-controlled mode. A filter was placed at the end of the endotracheal tube to measure aerosol delivery. Amikacin (1 g/8 mL) and salbutamol (5 mg/5 mL) were nebulized with an Aeroneb Solo® connected to its T-adapter or the Combihaler® spacer. Salbutamol (100 μg/actuation with 10 actuations) and beclomethasone (250 μg/actuation with 10 actuations) were delivered with a pMDI connected to a Minispacer®, an ACE® spacer, or a Combihaler® spacer. Drug delivery measurements were performed in volume-controlled mode in dry and humidified conditions. Drug deposits on the filter were assayed.

Results: The use of spacers and the T-adapter did not change the ventilation parameters (p>0.9). Aerosol delivery of salbutamol and Amikacin by nebulization increased up to three-fold with the Combihaler® compared with the T-adapter in humidified and nonhumidified conditions (p<0.05). Aerosol delivery of salbutamol and beclometasone by pMDI increased up to three-fold with the Combihaler® and the ACE® spacer compared with the Minispacer® in humidified and nonhumidified conditions (p<0.05). Aerosol delivery by pMDIs and vibrating mesh nebulizers using either a T-adapter or spacers was reduced by up to 62.5% in a humidified circuit compared with a nonhumidified circuit.

Conclusion: Aerosol delivery via pMDIs and vibrating mesh nebulizers is greater with large spacers (Combihaler® and ACE®) than with smaller spacers (Minispacer®) or a T-adapter, in both humidified and nonhumidified conditions. In humidified conditions, the aerosol delivery decreased with all spacers.

Keywords: aerosol delivery; mechanical ventilation; nebulizer; pMDI; spacer; vibrating mesh.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Administration, Inhalation
  • Adrenergic beta-2 Receptor Agonists / administration & dosage*
  • Adult
  • Aerosols
  • Albuterol / administration & dosage*
  • Amikacin / administration & dosage*
  • Anti-Bacterial Agents / administration & dosage*
  • Beclomethasone / administration & dosage*
  • Bronchodilator Agents / administration & dosage*
  • Equipment Design
  • Humans
  • Humidity
  • Materials Testing
  • Metered Dose Inhalers
  • Models, Anatomic
  • Nebulizers and Vaporizers*
  • Respiration, Artificial / instrumentation*
  • Ventilators, Mechanical*
  • Vibration


  • Adrenergic beta-2 Receptor Agonists
  • Aerosols
  • Anti-Bacterial Agents
  • Bronchodilator Agents
  • Amikacin
  • Beclomethasone
  • Albuterol