Interdependence of bronchial circulation and clearance of 99mTc-DTPA from the
airway surface.
Wagner, Elizabeth M., and W. Michael Foster.
Departments of Medicine and Environmental Health Sciences Johns Hopkins
University Baltimore, Maryland 21224
APStracts 8:0028A, 2001.
The extent to which the systemic vasculature is involved in soluble-particle uptake in the
conducting airways has not been studied extensively. In anesthetized, ventilated sheep, 6-
10 µl of technetium-99m-labeled diethylenetriamine pentaacetic acid (99mTc-DTPA)
was delivered through a microspray nozzle to a fourth-generation airway. Perfusion of
the cannulated bronchial artery was varied between control flow (0.6
ml«chemp»min«minus»1«chemp»kg«minus»1), high flow (1.8
ml«chemp»min«minus»1«chemp»kg«minus»1) or no flow (the infusion pump was
stopped). Airway retention of the radioactive tracer was monitored using gamma camera
imaging, and venous blood was sampled. During control perfusion, tracer retention at the
site of deposition at 30 min averaged 20 ± 6% (n = 7). With no flow, retention was
significantly elevated to 32 ± 8% (P = 0.03). In another group of sheep (n = 5) with a
control retention of 13 ± 4%, high flow resulted in an increase in tracer (25 ± 4%; P =
0.04). Maximum blood uptake of tracer was calculated by estimating circulating blood
volume and averaged 16% of total activity during control flow. Only during high-flow
conditions was 99mTc-DTPA in the blood decreased (10%; P = 0.04). Most of the tracer
was cleared by mucociliary clearance as was visualized by imaging. This component was
substantially decreased during no flow. The results demonstrate that both decreased and
increased airway perfusion limit removal of soluble tracer applied to the conducting
airways.
Received 27 May 2000; accepted in final form 20 November 2000
APS Manuscript Number A530-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 29 January 2001