WEBB, WAX, KUSAJIMA, PARKER, KAMIYAMA AND MURAKAMI 
265 
nary arterial presser not elevating blood to this 
level above the outflow tract of the right heart. 
Later, perhaps as a result of the increased ven- 
ous resistance, interstitial edema appears but as 
expected this is far greater in the dependent 
areas of the lung than in the superior portions. 
The early tremendous engorgement of the capil- 
lary beds and the progressive interstitial edema 
seems to be best explained by the constriction of 
the small pulmonary veins. Later after reinfu- 
sion the development of the capillary congestion 
adds alveolar capillary obstruction to the estab- 
lished more distal small pulmonary venous ob- 
struction. Wilson^^ and Sherman" and their 
co-workers have similarly observed the micro- 
circulatory changes in the lung during shock 
and have published findings very similar to 
ours. Wilson likewise found methyl predniso- 
lone to have a protective effect for the lung in 
low flow states. The mechanism of this awaits 
full definition, but there are many effects of the 
steroid which might be beneficial, such as the 
stabilization of lysosomes, protection of the cap- 
illary endothelium, and anti histaminic effects. 
SUMMARY 
Continuous observations have been made dur- 
ing a 2 hour period of hemorrhagic hypovole- 
mia at 40 mm Hg and following reinf usion. The 
pulmonary microcirculation has been photo- 
graphed by use of a metallurgic epiobjective mi- 
croscope utilizing dark field illumination with 
reflected light at powers up to 450 magnifica- 
tion. There are extremely significant differences 
in the response in the pulmonary vascular bed 
in the superior portion of the lung in contrast 
to that in the dependent areas of the lung sub- 
ject to a few millimeters Hg of additional hy- 
drostatic pressure. 
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DISCUSSION 
J. H. Block, Cornell University, New York 
City, N.Y. : I'd like to congratulate Dr. Webb on 
what I think is a really spectacular demonstra- 
tion. He has shown us some of the hemodynam- 
ics of the shock state and the normal state with 
the gradients between the two sides of the right 
circulation. Do these become abolished or im- 
proved at all with the addition of methylpredni- 
solone? 
Dr. Webb: Yes they do. We have additional 
