Albuterol delivery via tracheostomy tube.

HYPOTHESIS Albuterol delivery through a tracheostomy tube is affected by device (nebulizer vs metered-dose inhaler), interface (mask vs T-piece), bias flow, and humidification. METHODS A lift bar was placed between the chambers of a dual-chambered lung model such that a ventilator triggered simulated spontaneous breathing at a rate of 20 breaths/min, tidal volume of 0.4 L, and inspiratory-expiratory ratio of 1:2. An 8-mm inner diameter cuffed tracheostomy tube was placed through a semi-circular model that simulated a patient's neck. Four conditions of gas flow and humidification were used for the nebulizer experiments: heated aerosol (approximately 30 L/min, approximately 30 degrees C), heated humidity (approximately 30 L/min, approximately 30 degrees C), high flow without added humidity (approximately 30 L/min), or a nebulizer attached to the tracheostomy tube without additional flow. The nebulizer was filled with 4 mL that contained 2.5 mg of albuterol, and operated at 8 L/min. The nebulizer was tested with a T-piece or tracheostomy mask. For the metered-dose inhaler experiments, a spacer was used and actuation of the inhaler (100 microg per actuation) was synchronized with inhalation (4 actuations separated by > or = 15 s). When the spacer was used without additional flow, a valved T-piece was used with a 1-way valve placed either proximal or distal to the spacer. A filter was attached between the lung model and the distal end of the tracheostomy tube. Albuterol washed from the filter was measured by ultraviolet spectrophotometry. RESULTS For the nebulizer, the most efficient delivery was with no flow other than that to power the nebulizer and with a T-piece (p < 0.001). The most efficient method for aerosol delivery was metered-dose inhaler with a valved T-piece and placement of the 1-way valve in the proximal position (p < 0.001). The effect of humidity was unclear from the results of this study. CONCLUSIONS Albuterol delivery via tracheostomy was affected by the delivery device (nebulizer vs inhaler), bias gas flow, and the patient interface.