title: Effects of lung volume on clearance of solutes from the air spaces of lungs.
abstract: Several investigators have shown that the clearance rate of aerosolized 99mTc-labeled diethylenetriamine pentaacetate (DTPA, mol wt = 492, radius = 0.6 nm) from the air spaces of the lungs of humans and experimental animals increases with lung volume. To further investigate this phenomenon we performed a compartmental analysis of the 2-h clearance of DTPA from the lungs of anesthetized sheep using a new method to more accurately correct for the effects of DTPA recirculation. This analysis showed that the DTPA clearance in eight sheep ventilated with zero end-expired pressure was best described by a one-compartment model with a clearance rate of 0.42 +/- 0.15%/min. Ventilating eight sheep with an end-expired pressure of 10 cmH2O throughout the study increased the end-expired volume 0.4 +/- 0.1 liter BTPS and created a clearance curve that was best described by a two-compartment model. In these sheep 56 +/- 16% of the DTPA cleared from the lungs at a rate of 7.9 +/- 2.9%/min. The remainder cleared at a rate similar to that measured in the sheep ventilated with zero end-expired pressure (0.35 +/- 0.18%/min). Additional control and lung inflation experiments were performed using 99mTc-labeled human serum albumin (mol wt = 66,000, radius = 3.6 nm). In six control sheep ventilated with zero end-expired pressure the albumin clearance was best described by a one-compartment model with a clearance rate of 0.06 +/- 0.02%/min. The clearance rate in six sheep with increased lung volume was slightly larger (0.09 +/- 0.02, P less than 0.05) but was well described by a one-compartment model.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology, University of Texas Health Center, Tyler 75710.
authors.forename: B T
authors.initials: BT
authors.lastname: Peterson
authors.forename: H L
authors.initials: HL
authors.lastname: James
authors.forename: J W
authors.initials: JW
authors.lastname: McLarty
mesh_terms: D000336:Aerosols; D000818:Animals; D001417:Background Radiation; D008168:Lung / Q000000981:diagnostic imaging / Q000502:physiology*; D008176:Lung Volume Measurements; D008433:Mathematics; D008838:Microcomputers; D009942:Organometallic Compounds; D004369:Pentetic Acid; D011877:Radionuclide Imaging; D012119:Respiration; D012756:Sheep; D012984:Software; D013667:Technetium; D013668:Technetium Tc 99m Aggregated Albumin; D016284:Technetium Tc 99m Pentetate
chemical_list: D000336:Aerosols; D009942:Organometallic Compounds; D013668:Technetium Tc 99m Aggregated Albumin; D013667:Technetium; D004369:Pentetic Acid; D016284:Technetium Tc 99m Pentetate