Journal of Applied Physiology, Vol 54, Issue 2 576-581, Copyright © 1983 by American Physiological Society
Breathing He-O2 shifts the lung pressure-volume curve of the dog
N. Berend, K. L. Christopher and N. F. Voelkel
To determine whether breathing a mixture of 80% He-20% O2 affects the lung
pressure-volume (PV) curve, eight anesthetized paralyzed dogs were studied
in a volume-displacement plethysmograph. Static PV curves on air were
compared with PV curves obtained after equilibration with He-O2. The He-O2
PV curves were significantly shifted upward by an average of 5% total lung
capacity. There was no change in compliance, indicating that the shift was
due to lung expansion rather than a change in elasticity. Pretreatment of
the dogs with cyclooxygenase inhibitors abolished the PV shift with He-O2.
Four dogs had PV curves recorded on air and a mixture of O2, SF6, and Ne, a
gas mixture with the same density as air but with 45% greater viscosity.
The PV curve shift was even greater than observed with He-O2 and could
again be virtually abolished with a cyclooxygenase inhibitor. These results
suggest that breathing a high-viscosity gas mixture results in alveolar
duct dilatation due to the release of a prostaglandin bronchodilator. This
may need to be taken into account in the analysis of flow augmentation with
He-O2.
