A firefighter breathes in air normally as he enters a building following an explosion and fire. He has a meter that predicts the PO2 will approximate 15 mm Hg in his tissue fluids as he actively moves about the room. Select the best statement.
a. The large changes in PO2 tissue environments cause only very small changes in hemoglobin O2 saturation, and no oxygen is needed.
b. The firefighter is at about 10% hemoglobin O2 saturation, and he requires an external air tank.
c. The firefighter's hemoglobin saturation will be about one oxygen per hemoglobin, and he will require an external air tank.
d. The S-shaped saturation curve of hemoglobin is flat at this PO2, and O2 saturation doesn't change much with PO2 changes in mm Hg.