In vitro validation of a Respimat® adapter for delivery of inhaled bronchodilators during mechanical ventilation.

BACKGROUND

Inhaled bronchodilators are frequently used in patients with chronic obstructive pulmonary disease (COPD). However, there has been no efficient way to administer the long-acting anticholinergic tiotropium to mechanically ventilated patients. The aim of this in vitro study was to compare the fine particle dose (FPD) output of a specifically designed adapter with other accessory devices for the delivery of bronchodilators using the Respimat® (RMT) inhaler by simulating the specific inhalation flow profiles of patients with COPD.

METHODS

Using characteristic flow profiles from COPD patients being weaned off mechanical ventilation, an in vitro study was performed analyzing the FPD achieved with different accessory devices (connectors, spacers, AeroTrachPlus valved holding chamber), which can be used to deliver drugs from pressurized metered dose inhalers (pMDI) and RMT inhalers to artificial airways. Fenoterol pMDI, tiotropium RMT, and a fixed-dose combination of salbutamol and ipratropium delivered by pMDI or RMT, were used as bronchodilators. Aerosols were collected by a next-generation impactor.

RESULTS

The RMT inhaler, combined with a new in-line adapter, was superior to other inhaler device connector or spacer combinations in FPD delivery during simulated mechanical ventilation (p<0.01). The outcome with the RMT inhaler/RMT adapter combination during simulation of mechanical ventilation was comparable to the measurements with the RMT/AeroTrachPlus valved holding chamber during simulation of spontaneous breathing. The delivery rates of the RMT adapter were not significantly affected by the administered bronchodilators or by the type of artificial airway (endotracheal or tracheostomy tube) employed.

CONCLUSIONS

The RMT inhaler combined with the prototype in-line adapter was better than the other accessory device combinations in fine particle deposition of inhaled bronchodilators during mechanical ventilation. Further research is required to determine the clinical relevance of these in vitro findings.