Delivery efficiency of metered dose aerosols given via endotracheal tubes

Abstract

The authors studied the efficiency of delivery of the inhaled bronchodilator metaproterenol when delivered via an endotracheal tube (ETT) using a metered dose inhaler (MDI). They found that the percentage of drug exiting the ETT varied with tube size, ranging from 3.0 ± 1.9 for a 6.0 mm ETT to 6.5 ± 4.4 for a 9.0 mm ETT (mean ± SEM, P < 0.05). The efficiency of delivery was also affected by whether the MDI was activated before or after initiation of gas flow through the ETT, with activation into a flowing stream significantly more efficient. The authors conclude that an MDI can deliver a dose of drug to the trachea, but delivery efficiency is lower than reported for MDI delivery in spontaneously breathing patients.