Relationship of oxygen content to Po-2 for stabilized bubbles in the circulation: Theory

Stabilized bubbles can pass through capillary beds, recirculate for a few minutes or hours. and carry O-2 from the lungs to the tissues. Here, we develop the theory for the O-2 content-Po-2 relationship of bubbles and the alterations of the bubbles that are coupled to the O-2 transport. We provide examples for bubbles stabilized by a slowly permeating gas; bubbles stabilized by mechanical structures may behave similarly. Because there are two mechanisms for O-2 unloading (lowering of Po-2 and shrinkage), the bubbles release a large fraction of their O-2 content at high Po-2; when pure O-2 is breathed, one-half of the content of a 3-mu m-radius bubble is released before Po-2 falls to 500 Torr. The possibility that stabilized bubbles could become a clinical tool for therapeutic transport of O-2 raises many issues to be investigated. The high-unloading Po-2 offers opportunities for delivering O-2 by diffusion to poorly perfused regions of the tissue but also presents a hazard of O-2 toxicity to perfused tissue.