title: The rapid reversibility of effects of changing lung volume on the clearance rate of inhaled 99Tcm-DTPA in man.
abstract: Five normal non-smoking subjects inhaled an aerosol of 99Tcm-DTPA in saline with a mass median aerodynamic diameter of 0.6 micron. The rate of clearance (k) of the inhaled 99Tcm-DTPA from lung to blood was measured using a gamma scintillation camera with computer data acquisition. During a single clearance study the subjects voluntarily breathed close to total lung capacity (TLC) and close to residual volume (RV). They breathed at one volume for 5 min, then at the opposite volume for 5 min and finally reverted to the original volume for 5 min with a 1 min pause between each manoeuvre. The order in which each subject performed these breathing patterns was randomized. Tidal volume, respiratory frequency and end expired volume were measured with a water spirometer. When they breathed close to TLC the rate of clearance increased (k = 4.62 +/- 1.03%/min) compared with breathing close to RV (k = 1.96 +/- 0.5%/min). This effect of changing volume was immediately reversible after adopting each new lung volume. There were no significant changes in tidal volume or respiratory frequency between each 5 min period. There was no significant difference between the clearance increased (k = 4.62 +/- 1.03%/min) compared with breathing close to RV (k = 1.96 +/- 0.5%/min). This effect of changing volume was immediately reversible after adopting immediate and reversible.
authors.affiliation: Department of Respiratory Physiology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: P S
authors.initials: PS
authors.lastname: Woolman
authors.forename: D K
authors.initials: DK
authors.lastname: Jones
authors.forename: R W
authors.initials: RW
authors.lastname: Barber
authors.forename: T W
authors.initials: TW
authors.lastname: Higenbottam
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004369:Pentetic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013667:Technetium; D016284:Technetium Tc 99m Pentetate
chemical_list: D009942:Organometallic Compounds; D013667:Technetium; D004369:Pentetic Acid; D016284:Technetium Tc 99m Pentetate