Comparison of Medication Delivery by T-Nebulizer with Inspiratory and Expiratory Reservoir

Using an in-vitro model, I evaluated the effect of the presence in a nebulizer system of an inspiratory or expiratory reservoir 6 inches in length (0.15 m, internal volume about 50 mL) on the amount of aerosolized medication made available to the patient. METHOD: The test apparatus included a negative-pressure ventilator that entrained aerosol from a nebulizer into a 'patient' bacteria filter that was weighed before and after each aerosol deposition. Seven trials were run with each of three system configurations: Group 1-with an expiratory reservoir, Group 2-without a reservoir, and Group 3-with an inspiratory reservoir in place. RESULTS: Weighing the filter in Group 1 indicated that 0.22 g (± 0.04) was routed to the patient, in Group 2, 0.18 g (<0.04), and in Group 3, 0.14 g (± 0.01). CONCLUSION: A T-nebulizer with an expiratory reservoir offers the patient significantly more (p < 0.05) medication than does either a T-nebulizer with an inspiratory reservoir or one without a reservoir.