A comparison of bronchodilator therapy delivered by nebulization and metered-dose inhaler in mechanically ventilated patients

Background: The optimal method of delivering bronchodilators in mechanicall y ventilated patients is unclear. The purpose of this study was to compare die pulmonary bioavailability of albuterol delivered by the nebulizer, the metered-dose inhaler (MDI) and spacer, and the light-angle MDI adaptor in v entilated patients using urinary analysis of drug levels. Methods: Mechanically ventilated patients who had not received a bronchodil ator in the previous 48 h and who had normal renal function were randomized to receive the following: (1) five puffs (450 mu g) of albuterol delivered by the MDI with a small volume spacer; (2) five puffs of albuterol deliver ed by the MDI port on a right-angle adaptor; or (3) 2.5 mg albuterol delive red by a nebulizer. Urine was collected 6 h after the administration of the drug, and the amounts of albuterol and its sulfate conjugate were determin ed in the urine by a chromatographic assay. Results: Thirty patients were studied, 10 in each group: their mean age and serum creatinine level were 62 years and 1.3 mg/dL, respectively. With the MDI and spacer, (mean +/- SD) 169 +/- 129 mu g albuterol (38%) was recover ed in the urine; with the nebulizer, 409 +/- 515 mu g albuterol (16%) was r ecovered in the urine; and with the MDI port on the right-angle adaptor, 41 +/- 61 mu g albuterol (9%) was recovered in the urine (p = 0.02 between gr oups). The level of albuterol in the urine was below the level of detection in four patients in whom the drug was delivered using the right-angle MDI adaptor. Conclusion: The three delivery systems varied markedly in their efficiency of drug delivery to the lung. As previous studies have confirmed, this stud y has demonstrated that using an MDI and spacer is an efficient method for delivering inhaled bronchodilators to the lung. The pulmonary bioavailabili ty was poor with the right-angle MDI port. This port should not be used to deliver bronchodilators in mechanically ventilated patients.