The Journal of Thoracic and Cardiovascular Surgery, Vol 74, 118-125, Copyright © 1977 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
The role of carbon dioxide in the development of pulmonary insufficiency
J Askanazi, JF Neville Jr, SD Wax, EL Hanson, PB Kane and WR Webb
The effects of carbon dioxide (PCO2 = 40 versus PCO2 = 20) on pulmonary
function changes during 2 hours of hemorrhagic hypotension followed by
resuscitation are evaluated in 21 dogs. Pulmonary hemodynamics, mechanics,
gas exchange, functional residual capacity, and morphology are studied. In
the preshock period, hypocapnia is associated with a decreased cardiac
output, increased dead space, and increased alveolar- arterial (A-a)
gradiant (room air). During the period of hypotension, all parameters in
both groups changed similarly. After resuscitation, the A-a gradients in
the two groups further widened. Following the return to control levels of
normocapnia in all animals, the group which had been hypocapnic during the
hypotensive episode continued to show increased shunting (20 versus 13
percent, p less than 0.05). These results correlated well with
cinemicroscopic findings, which showed the normocapnic group to have less
interstitial edema and better capillary flow.
