Absorption of in vivo inert gas bubbles

The resolution rates of gas bubbles in perfused tissue are examined using a mathematical model which is consistent with transient-state and steady-state data from large gas pocket experiments. The tissue surrounding the bubble is assumed to have an infinite number of infinitesimally small capillaries (distributed sink). The time for complete disappearance of a bubble depends on initial bubble size. blood perfusion rate of the tissue, physical characteristics of the inert gas and the fraction (1 - Pa/Pg), where Pa and Pg are inert gas partial pressures in the surrounding tissue and inside the bubble, respectively. Calculated time for disappearance of a nitrogen bubble of 1 mm radius in an O₂-breathing man is 100-250 min, depending on blood perfusion. Breathing of air increases the time of persistence of the bubble about 10-fold. The 'transient state', when gas is dissolving in the immediate surroundings of the bubble, is most influential when there is no perfusion and the partial pressure gradient gas volume is the largest. However, our major conclusion is that the initial transient state has little effect on total lifetime of the bubble in any case.