Tissue Oxygen and Carbon Dioxide Tensions During Hyperbaric Oxygenation

BREATHING AIR enriched with O 2 in chambers where the ambient pressure has been artificially elevated (hyperbaric oxygenation) leads to vast increases in the amount of O 2 carried in physical solution in the arterial blood. In principle, the requirements of the organism may be met entirely by the O 2 dissolved in plasma without recourse to oxyhemoglobin; as a result, the O 2 pressure gradient between blood and tissues remains high even while blood is traversing the capillary, and tissue areas deprived by disease states of an adequate blood supply may be nourished with O 2 by this large pressure gradient. Even though hyperbaric chambers for therapeutic purposes in man are increasing, 1-3 two potential physiological consequences of hyperbaric oxygenation, which may limit its clinical usefulness, have been difficult to study. 4,5 These are (1) vasoconstriction, either in toto or in individual organs, 6 which may reduce blood flow