Effects of hypoxic pulmonary vasoconstriction on pulmonary gas
exchange.
Brimioulle, Serge, Philippe Lejeune, Robert Naeije.
Laboratory of cardiovascular and respiratory physiology, Free
University of Brussels, Brussels, Belgium
APStracts 3:0243A, 1996.
Several reports have suggested that hypoxic pulmonary vasoconstriction
(HPV) might deteriorate pulmonary gas exchange in severe hypoxia. We
therefore investigated the effects of HPV on gas exchange in normal
and diseased lungs. We incorporated a biphasic HPV stimulus-response
curve observed in intact dogs [J Appl Physiol 77:476, 1994] into a
50-compartment lung model [Respir Physiol 7:88, 1969], to control the
amount of blood flow directed to each lung compartment according to
the local hypoxic stimulus. The resulting model was shown to
accurately reproduce the blood gases modifications caused by HPV
changes in dogs with acute lung injury. In single lung units, HPV was
found to have a moderate protective effect on alveolar oxygenation,
which was maximal at near-normal alveolar (PAO 2 75-80 mmHg), mixed
venous (PvO 2 35 mmHg) and 50 % hemoglobin saturation (P 50 24 mmHg)
oxygen tensions. In simulated diseased lungs associated with arterial
oxygen tensions (PaO 2 ) of 40-60 mmHg, however, HPV was found to
increase the PaO 2 by 15-20 mmHg. We conclude that HPV can improve
arterial oxygenation substantially in respiratory failure.
Received 15 May 1995; accepted in final form 7 May 1996.
APS Manuscript Number A502-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 May 96