Pulmonary clearance of 99mTc-DTPA in experimental surfactant dysfunction treated with surfactant instillation.
BACKGROUND
Breakdown of the alveolo-capillary barrier is a characteristic feature of respiratory distress syndrome. Restoration of alveolo-capillary barrier function may be an important aspect of surfactant replacement therapy. We examined the effect of surfactant instillation on alveolo-capillary barrier function in an experimental model of surfactant dysfunction by measuring pulmonary clearance of 99mTc-DTPA.


METHODS
Nineteen rabbits were tracheotomized and mechanically ventilated. Surfactant dysfunction was induced by administration of a synthetic detergent in aerosol form. Detergent was given to 13 rabbits; seven rabbits were then treated with instillation of natural surfactant, whereas six rabbits received saline. Six rabbits were used as untreated controls. An aerosol of 99mTc-DTPA was administered to all animals and the pulmonary clearance was measured with a gamma camera.


RESULTS
99mTc-DTPA cleared from the lungs with a half-life of 71 +/- 22 min in the control animals, 21.4 +/- 7.4 min in the surfactant-treated animals and 5.8 +/- 1.5 min in the saline-treated animals. The difference in half-life between groups was highly significant (P < 0.001). There was no change in arterial oxygenation or compliance in controls or in animals treated with saline. In animals treated with surfactant, a small transient reduction in arterial oxygen tension and a more long-standing reduction in compliance were observed.


CONCLUSIONS
Surfactant treatment thus significantly attenuated the effect of detergent treatment but did not restore alveolo-capillary transfer of 99mTc-DTPA to normal.
Nilsson
K
K
Department of Clinical Physiology, University of Lund, St Göran's Hospital, Stockholm, Sweden.
John
J
J
Lachmann
B
B
Robertson
B
B
Wollmer
P
P
D000818:Animals; D002199:Capillary Permeability; D003902:Detergents / Q000494:pharmacology; D004143:Dioctyl Sulfosuccinic Acid / Q000494:pharmacology; D006207:Half-Life; D008168:Lung / Q000473:pathology; D008170:Lung Compliance; D010539:Permeability; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D011663:Pulmonary Surfactants / Q000187:drug effects / Q000494:pharmacology / Q000502:physiology*; D011817:Rabbits; D012128:Respiratory Distress Syndrome / Q000503:physiopathology; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics*
D003902:Detergents; D011663:Pulmonary Surfactants; D004143:Dioctyl Sulfosuccinic Acid; D016284:Technetium Tc 99m Pentetate