2003 OPEN FORUM Abstracts
IN VIVO EFFECT OF PARTICLE SIZE ON LUNG DEPOSITION OF TWO DROPS OF 99mTc-DTPA IN AN ANIMALA MACAQUE MODEL OF INFANT MECHANICAL VENTILATION
JB Fink1, JC Dubus1Dubus2,32, L Vecellio None21, JB Fink3, M de Monte21, D Grimbert21, C Valat21, J Montharu21, N Behan13, P Diot21
1Aerogen Inc., Mountain View, CA, USA.1Groupe 2Groupe de Pneumologie, INSERM EMI-U 00-10, IFR 120, Tours, France; 32Dept of Pediatrics, Timone-Enfants Hospital, Marseille, France; 3Aerogen, Inc., Mountain View, CA, USA.
INTRODUCTION : In vivo delivery of aerosol during mechanical ventilation of infants has been limited to less than 1% as determined by scintigraphy (Fok et al, Pediatr Pulmonol.1996; 21(5):301-9). Our aim was to compare the lung deposition of 99mTc-DTPA in an animal model of neonatal ventilation using a prototype version of thof the next generatione Aeroneb Professional Nebulizer System (Aerogen, Inc.) synchronized to generate aerosol during inspiration, with separate aerosol generators producing aerosols with a 2.8µm orand 4.8 mm volume median diameter aerosols as determined by laser (Malvern).
Methods: Four macaques (2.6 kg average) were intubated with a 3.0 mm Portex uncuffed endotracheal tube (ETT) and ventilated with a Draeger Babylog ventilator (respiratory rate 40/min, peak inspiratory pressure: 12-14 mbar, PEEP: 2 cm H2O, I/E ratio: 1:2). Thirty µL (two drops containing 2 mCi) of 99mTc-DTPA were charged in the nebulizer and delivered with the nebulizer placed in the inspiratory line via using a T-piece 10 cm from the Y-piece. A gamma camera was used to measure aerosol radioactivity deposited in the lungs. Measurements were repeated with each particle size (n=6).
RESULTS: Aerosol delivery of 30 µL (ttwo drops (2mCi)) of 99mTc-DTPA with both particle sizes was sufficient to provide good visualization of lung fields in all animals. A, with a greater percent of total dose (mean %) was achieved with the smaller (2.8 mm) particle size.
|Particle Size (volume median diameter)||Lung Deposition (mean % ± SD)||Range (%)|
|2.8 mm||20.8±19.1||6.0 - 48.5|
|4.8 mm||12.3±4.1||6.0 - 15.0|
Conclusions: While the smaller particle was associated with greater deposition, both size aerosol generators usedes delivered with the prototype version of thenext generation Aeroneb Professional Nebulizer delivered an order of magnitude greater proportion of thmore dose to the lungs of ventilated macaques than previously described in animal models of infant ventilation. The ability to efficiently deliver small doses of medication/ radiationradiodiagnostic materials to the lungs of ventilated infants has positive implications for development of therapeutic andimproved diagnostic (and therapeutic) options.