Journal of Applied Physiology, Vol 70, Issue 6 2439-2447, Copyright © 1991 by American Physiological Society
Restriction of regional blood flow and diaphragmatic contractility
A. Comtois, F. Hu and A. Grassino
Notre Dame Hospital, University of Montreal, Quebec, Canada.
We have tested the hypothesis that the diaphragmatic head-to-head arterial
anastomosis system should maintain adequate diaphragmatic function even
during occlusion of some of its arteries. In six anesthetized open-chest
dogs, left phrenic vein blood flow (Qphv) was measured by pulsed Doppler
flowmetry. Contractility was measured by sonomicrometry in the left costal
and crural diaphragm. The diaphragm was paced for 15 min by continuous
bilateral supramaximal phrenic nerve stimulation. In five separate runs the
following arteries were occluded at minute 5: 1) left phrenic artery, 2)
internal mammary artery (IMA), 3) left phrenic artery and IMA, 4)
descending aorta, and 5) descending aorta and IMA. Occlusion was then
released at minute 10 of the run. In runs 1-3 there were no changes in
contractility in costal or crural diaphragm and no changes in Qphv.
However, in runs 4 and 5, Qphv decreased to 55.2 +/- 7.4 and 24.0 +/- 6.5%
of control values, respectively. In run 4, percent maximum shortening from
functional residual capacity (%LFRC) of the crural diaphragm decreased by
39.1%, while %LFRC of the costal diaphragm increased by 41.4% and abdominal
pressure decreased by 47.0%. In run 5, abdominal pressure decreased by
53.5% and %LFRC of the crural and costal diaphragm decreased by 45.5 and
5.8%, respectively. Also relative postocclusion hyperemia was greater in
run 5 (64.8%) than in run 4 (40.2%).(ABSTRACT TRUNCATED AT 250 WORDS)
