Sites of deposition of aqueous aerosols: a study of efficiency of delivery systems for lung ventilation imaging in man.
A study was made of the deposition of 99Tcm-DTPA aerosol in the components of a jet nebulizer-based aerosol production system. Three impaction devices were compared: a ball-bearing separator, a virtual impactor and a step separator. In addition a comparison was made of two types of tubing which carried aerosol from nebulizer to mouthpiece: corrugated and smooth-walled tubing. The retention of aerosol following inhalation was measured in five normal volunteers using different patterns of breathing. Using an aerosol production system which included a ball-bearing separator only a mean of 11% of the radioactivity loaded into the nebulizer was emitted as an aerosol. Some 18% remained in the ball-bearing separator. The ball-bearing and step separators produced similar total outputs (7% and 6% minimum), the step separator producing marginally higher mean output/min. The virtual impactor produced a lower output than the other two impactors studied, only 1%. A larger proportion of the aerosol output was deposited on corrugated tubing (7%) compared with smooth-walled tubing (1%). The retained fraction of the aerosol inhaled by subjects ranged from 16% to 43%. A higher fraction was retained when subjects inhaled deeply and held their breath for 10 s between each breath. The efficiency of radionuclide deposition from aerosol generator to patient ranged from 1.1% to 6% and was determined more by the retention in the subject than by choice of separator or tubing.
Woolman
P S
PS
Department of Respiratory Physiology, Addenbrookes Hospital, Cambridge, UK.
Coutts
C T
CT
Mole
D R
DR
Dendy
P P
PP
Higenbottam
T W
TW
D000336:Aerosols; D004867:Equipment Design; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D009330:Nebulizers and Vaporizers / Q000592:standards*; D009942:Organometallic Compounds; D010316:Particle Size; D004369:Pentetic Acid; D011877:Radionuclide Imaging; D012119:Respiration; D013667:Technetium; D016284:Technetium Tc 99m Pentetate
D000336:Aerosols; D009942:Organometallic Compounds; D013667:Technetium; D004369:Pentetic Acid; D016284:Technetium Tc 99m Pentetate