On exposure to oxygen at a pressure of 3
atmospheres in a hyperbaric chamber, there is sufficient dissolved
oxygen in the plasma to meet the average requirements of resting
tissue by means of dissolved oxygen alone without contribution
from oxygen bound to hemoglobin. This provides part of the
rationale for the use of hyperoxia in situation in which the
hemoglobin’s oxygen carrying capacity has been impaired e.g.
carbon monoxide poisoning. However, the main improvement
in cellular oxygenation results from an increase in the oxygen
tension gradient consequent upon breathing oxygen and this
drives the diffusion of oxygen from capillary blood into cells.