234 
PULMONARY MODELS 
Series 3 Dog 6962. Hale. 26.5 Kqs. 
7^ — * 7^ - 
7^ — ' . 
3 ^ 
1=: 
'O 42.5 — - 7.88 390 .0495 11.4 4.434 .055 .1252 .0072 .0163 .5551 .0723 413 303 7.35 84.1 39.1 92 150 200/105 135 - 1.7 
tjo 5* 6 88 313 0455 14 9 4.651 .0306 .0988 .0023 .0073 .4595 .0340 7.29 86.7 38.5 92.5 165 165/110 135 5.0 
t30 
tgo 34 800 "4 311 7.35 81.2 42.6 92 
tjg S 7 JO 243 .0342 24.2 5.871 .0228 .1001 .0098 .0431 .5877 .2530 7.30 77.3 47.3 90.5 210 145/110 125 6.0 
Ho ' 
h20 30.5 1900 280 310 7.29 70.4 48.2 88.5 
ti5oS 8 04 184.5 .0231 34.0 6.273 .0210 .114 .0099 .0537 .7151 .3369 7.30 65.7 47.2 87.5 180 135/110 120 7.5 
hso^ 
tl80 31 1650 283 7.25 51.8 48.9 81 
t2ioS 12 76 124 4 .00975 75 9.331 .0298 .2265 .0209 .1592 2.113 1.491 7.22 30.0 64.0 59 150 170/125 150 13.0 
1650 323 7.22 31.4 138.3 36 
7.289 30.2 98.8 
Table II. — Physiologic Data Representative of Group 111 Dogs 
respiratory rate and decreased tidal volume 
(Table II). Other physiologic alterations ob- 
served in continually overloaded dogs ranged 
from initial changes in lung function, cited 
above, to decrease oxygen saturation and res- 
piratory acidosis. Respiratory mechanics were 
also compromised by the development of con- 
gestion and edema within the lungs, as ob- 
served in the present ultrastructUre study. The 
earliest physiologic changes correlated with the 
cytopathologic observations of edema (e.g., dis- 
placement of collagen bundles by edema fluid, 
vacuolization and thickening of endothelial 
cells). Edema about the small airways may have 
increased airway resistance. Figure 4 shows 
several adjacent alveoli from Group III dogs; 
noteworthy are the smooth continuous alveolar 
walls and the reduction in the diameter of the 
pores of Kohn.i^ This morphology is consistent 
with edematous tissues which presumably have 
occluded the pores of Kohn. Companion light 
and transmission electron microscopic observa- 
tions confirm edema at the site of this lung 
tissue sample. 
Congestive changes also may have contributed 
to decreased pulmonary function, causing both 
a decrease in compliance and an increase in 
airway resistance.^^ Similarly, compliance may 
have fallen because congestion of the alveoli 
led to changes in surface forces and alveolar 
collapse. The latter observation was substan- 
tiated in scanning electron microscopic observa- 
tions which demonstrated focal atelectasis, 
especially in the lower lobes, of lungs from con- 
tinuously overloaded dogs. Any decrease in 
lung compliance and increase in airway resist- 
ance, whether due to congestion or edema, will 
increase the energy cost of breathing. Thus, 
specific indices of pulmonary function, e.g., 
transpulmonary pressure and the resistive work 
of breathing, will reflect the observed edema 
and congestion. 
All of the effects caused in Group III dogs 
were abrogated in the five Group IV animals, 
which were given furosemide (0.8 mg/kg) ev- 
ery 2 hours, during infusion. 
It is significant that in this study with normal 
dogs, it was necessary to infuse massive vol- 
umes of fluid over six hours in order to produce 
respiratory insufficiency. The dogs developed 
pulmonary edema only when the retained fluid 
equalled one-fourth of their body weight. It is 
most probable, however, that the degree of acute 
respiratory insufficiency can be induced with a 
smaller total volume of infusate in dogs, whose 
pulmonary circulation has been previously com- 
promised. Thus, these observations and the 
associated canine model of ARI induced by con- 
