19 pigs had glass beads administered into the trachea so as to significantly depress arterial oxygen tension. Arterial, venous, and muscle oxygen tensions were recorded for up to 12 hrs while 0.1 ml/kg DDFPe was administered 1-3 times. The arterial, mixed venous, and tissue oxygen tensions increased with each infusion and CO2 levels fell. Improvements lasted about 2 hrs after each infusion. Toxic effects of the treatment were not observed.