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°C), heated humidity (approximately 30 L/min, approximately 30°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 μg per actuation) was synchronized with inhalation (4 actuations separated by ≥ 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.