Tissue oxygen pressure in normal myocardium and across the border zone during coronary artery occlusion in the pig. Effects of different arterial oxygen pressures.

Tissue oxygen pressure (ptO2) in the pig heart was measured with two different oxygen electrodes: We measured ptO2 in normal myocardium with the MDO electrode while oxygen gradients across the border zone, during acute coronary artery occlusion, were measured with an array-multiwire-electrode (AME). The aim of the study was to investigate the effects of increased arterial oxygen pressure (paO2) during repeated, short-lasting (5 min) coronary artery occlusions. During ventilation with an inspired oxygen fraction (FIO2) of 0.3 the ptO2 levels in normal myocardium increased significantly, while the distribution type of ptO2 values remained normal. During ventilation with FIO2 0.7 there was an uneven distribution of ptO2 values indicating microcirculatory disturbances, however, no ischemic values were seen. We found no indication for any influence on the ptO2 of the border zone.