Inhalation therapy with metered-dose inhalers and dry powder inhalers in mechanically ventilated patients.

Pressurized metered-dose inhalers (pMDIs) are commonly employed for administering bronchodilator aerosols to mechanically ventilated patients. Although it is feasible to employ dry powder inhalers in ventilator circuits, the presence of humidity in the ventilator circuit could reduce their efficiency. A complex array of factors influence drug delivery from pMDIs during mechanical ventilation, and subtle differences in the method of administration can markedly alter aerosol deposition in the lower respiratory tract. However, when the technique of administration is optimized, the efficiency of drug delivery from pMDIs in mechanically ventilated patients is comparable to that in ambulatory patients. Significant bronchodilator effects are observed with as few as 4 puffs from a pMDI and cylindrical spacer. In mechanically ventilated patients, pMDIs are a cost-effective, convenient, and safe method for delivering bronchodilator aerosols.