AEROSOL DELIVERY DURING CONTINUOUS NEBULIZATION

Background and objectives: Continuous administration of aerosolized be ta(2)-agonists has been suggested as am effective treatment for severe reversible airways disease. To facilitate continuous therapy and avoi d a feed system for small-volume nebulizers (SVNs), a large-volume med ication nebulizer (Vortran HEART) was developed. The goal of this stud y was to determine actual drug delivery of the HEART and conventional SVNs for both adult and pediatric breathing patterns, Design: Output s tudies were conducted on comparable samples of CIS-US AeroTech II and Hospitak PowerMist SVNs and Vortran HEART large-volume continuous nebu lizers. To duplicate clinical aerosol delivery va an aerosol mask, dru g particles were inhaled through the mouth of a model of a human face for two test breathing patterns (adult=tidal volume (VT) of 500 mL, 20 breaths/min, duty cycle of 40%; pediaric=VT of 100 mL, 35 breaths/min , duty cycle of 40%), generated by a ventilator. Radiolabeled Particle s of saline solution, confined to behave identically to albuterol, wer e collected on absolute filters at the mouth of the face to measure th e actual mass of albuterol particles delivered to the airway opening. Results: The AeroTech II and PowerMist SVNs delivered 5.14 and 3.74 mg /h, respectively, for- the adult breathing pattern and 2.97 and 2.46 m g/h, respectively, for the pediatric breathing pattern. Drug delivery rates of the HEART were a function of drug concentration and ranged fr om 0.87 to 3.48 mg/h for the adult breathing pattern. For the pediatri c breathing pattern, drug delivery rate was a function of drug concent ration and inspired minute ventilation and ranged from 0.41 to 1.83 mg /h. Conclusion: Our data demonstrate that drug delivery to the patient , expressed as inhaled mass over time, is similar for continuous nebul ization (HEART system) and intermittently filled SVNs. In addition, fo r all nebulizers, the influence of the pediatric breathing pattern nee ds to be considered. Continuous nebulization permits the redistributio n of health-care personnel and may reduce the costs of therapy.