Safety and efficiency of metered dose inhaler delivery of salbutamol in the intubated rabbit

Objective: To determine the safety and efficiency of metered dose inhaler s albutamol delivered to the intubated rabbit. Design: Prospective, comparative, five-group laboratory investigation, Setting: Animal laboratory, Department of Nuclear Medicine. Subjects: A total of 30 adult, anesthetized New Zealand White rabbits. Interventions: Three groups of rabbits underwent tracheal intubation throug h a tracheostomy and received 5 puffs of (TcO4)-Tc-99m salbutamol delivered at the elbow connector (group 1) or via a catheter with its distal tip pos itioned at the midpoint (group 2) or bevel of the endotracheal tube (group 3), No intervention was provided for the rabbits in the fourth group. A fif th group underwent tracheal intubation through the mouth and received salbu tamol (5 puffs) delivered at the bevel of the endotracheal tube. Measurements: Delivery efficiency was expressed as the ratio of radioactivi ty emitted from lungs and trachea to the total radioactivity of the adminis tered dose. Histopathologic injury scores were assigned to each trachea or lung specimen. Main Results: Delivery efficiency was 30 times greater in groups 3 and 5 (f ull catheter) than in group 1 (elbow), The injury scores were similar in al l groups. Conclusion: We conclude that the increased efficiency obtained by administr ation of metered dose inhaler salbutamol at the distal tip of endotracheal tube is not necessarily associated with increased epithelial injury.