Diffusing capacity and pulmonary capillary blood flow at hyperbaric pressures.

tissue in milliliters (VT) was measured by plotting the acetylene disappearance with different times of breath holding in each subject (4). The concentrations of neon, carbon monoxide, and acetylene were approximately constant in the inspired mixture, being 0.5%, 0.4%, and 0.5%, respectively, with a balance of oxygen and nitrogen. Four separate inspired mixtures were employed in which the oxygen concentrations were 6%, 21%, 60%, and 98%o. By breathing different concentrations of oxygen for a few breaths followed by a breath of one of the inspired mixtures described, the alveolar oxygen tension of the subject during the breath holding period could be varied at will. Neon, carbon monoxide, acetylene, and carbon dioxide