109 PULMONARY DEPOSITION OF SALBUTAMOL AEROSOL DELIVERED BY METERED DOSE INHALER (MDI), JET NEBULIZER AND ULTRASONIC NEBULIZER IN MECHANICALLY VENTILATED RABBITS

Technetium-99m labelled Salbutamol was administered through a tracheostomy to ventilated rabbits by either an MDI (5 puffs,100μg/puff) aided with a spacer (MV15 Aerochamber, Trudell, Canada) (Group1, n=7); or by nebulization (100μig/kg in 3ml Technetium-99m labelled 5% albumin). Nebulization was carried out for 20 min. with a Jet (Hudson, USA) (Group 2, n=11)or Ultrasonic device (Siemens, Sweden) using either a standard (Group 3, n=6) or a small (Group 4, n=7) reservoir. Lung deposition was estimated by gamma counting of the autopsy lung specimens: mean(sd):Salbutamol was uniformly distributed in the lungs in group 1 and 2, but showed a predilection for the right anterior azygous lobes and the central lung regions in group 3 and 4.Conclusion: in delivering Salbutamol to ventilated rabbits, this Ultrasonic device provides greater lung deposition but less uniform distribution than either Jet or MDI. Reducing reservoir volume enhances its efficiency of delivery further, but also yields differential deposition in lobes.