The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts


Christopher M. Piccuito, RRT; Dean R. Hess, PhD, RRT, FAARC. Massachusetts General Hospital and Harvard Medical School, Boston MA.

Background: Inhaled albuterol is occasionally used in spontaneously breathing patients with a tracheostomy tube. However, there has been little study of the best technique for albuterol delivery in this setting.

Hypothesis: Albuterol delivery through a tracheostomy tube is affected by type of aerosol delivery (nebulizer vs MDI), patient interface (mask vs T-piece), and humidification of the inspired gas.

Methods: A Puritan-Bennett 7200 ventilator was attached to one chamber of a dual-chambered test lung. A lift bar was placed between the chambers such that the ventilator triggered simulated spontaneous breathing of the second chamber at a rate of 20/min, tidal volume of 0.4 L, and I:E 1:2 (measured with a Novametrix NICO). The tracheostomy tube (8 mm cuffed Portex Blue Line) was placed through a semicircular model simulating a patient's neck. Four conditions of gas flow and humidification were used for the nebulizer experiments: heated aerosol (~30 L/min, ~30° C), heated humidity (~30 L/min, ~30° C), high flow without added humidity (~30 L/min), or nebulizer attached to the tracheostomy tube without additional gas flow. A Hudson Micro Mist nebulizer was filled with 4 mL containing 2.5 mg of albuterol and operated at 8 L/min. The nebulizer was tested with a T-piece or tracheostomy mask which was inserted 6 in from the interface. For the MDI experiments, a Monaghan AeroVent spacer was used and actuation of a pressurized MDI (90 mcg per actuation) was synchronized with inhalation (4 actuations separated by =15 s). When the AeroVent was used without additional flow or humidity, a 1way valve system was placed either proximal or distal to the AeroVent. A Puritan-Bennett D/Flex filter was attached between the lung model and the distal end of the tracheosstomy tube. Albuterol washed from the filter was measured by UV spectrophometry.

Results: For the nebulizer (Figure 1), 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 by MDI with dry circuit, T-piece, and placement of the 1-way valve in the distal position (P<0.001) (Figure 2).

Conclusions: Albuterol delivery by tracheostomy is affected by the aerosol delivery device (nebulizer vs inhaler), by humidification of the inspired gas, by total gas flow, and by patient interface. We found the MDI the most efficient method of aerosol and this should be subjected to clinical study.

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