Effect of raised thoracic pressure and volume on 99mTc-DTPA clearance in humans
Although positive airway pressure is often used to treat acute pulmonary edema, the effects on epithelial solute flux are not well known. We measured independently the effect of 1) positive pressure and 2) voluntary hyperinflation on the clearance of inhaled technetium-99m-labeled diethylenetriaminepentaacetic acid (/sup 99m/Tc-DTPA) in six nonsmokers and six smokers. Lung volumes were monitored by inductance plethysmography. Each subject was studied in four situations: 1) low end-expiratory volume (LO-), 2) low volume plus 9 cmH2O continuous positive airway pressure (LO+), 3) high end-expiratory volume (HI-), and 4) high volume plus continuous positive airway pressure (HI+). The clearance half time of 99mTc-DTPA for the nonsmokers decreased from 64.8 +/- 7.0 min (mean +/- SE) at LO- to 23.2 +/- 5.3 min at HI- (P less than 0.05). Positive pressure had no synergistic effect. The mean clearance half time for the smokers was faster than nonsmokers at base line but unaffected by similar changes in thoracic volume and pressure. We conclude that, in nonsmokers, positive airway pressure increases /sup 99m/Tc-DTPA clearance primarily through an increase in lung volume and that smokers are immune to these effects.
- Research Organization:
- Hammersmith Hospital, London, England
- OSTI ID:
- 5327652
- Journal Information:
- J. Appl. Physiol.; (United States), Journal Name: J. Appl. Physiol.; (United States) Vol. 5; ISSN JAPYA
- Country of Publication:
- United States
- Language:
- English
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551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHELATING AGENTS
CLEARANCE
DRUGS
DTPA
DYNAMIC FUNCTION STUDIES
EXCRETION
HOURS LIVING RADIOISOTOPES
INHALATION
INTAKE
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LUNG CLEARANCE
MAMMALS
MAN
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PRESSURE DEPENDENCE
PRIMATES
RADIOISOTOPES
RADIOPROTECTIVE SUBSTANCES
TECHNETIUM 99
TECHNETIUM ISOTOPES
VERTEBRATES
YEARS LIVING RADIOISOTOPES