<prompt> A patient is breathing air at sea level and has a respiratory exchange ratio of 1.0. The aerial blood values are: PO2 90 mm Hg ;PCO2 20 mm Hg and pH 7.30. These indicate that the:Alveolar-aerial PO2 difference exceeds 20 mm Hg.Plasma bicarbonate concentration is lowPatient is hyperventilatingAll of the above  <response>: The alveolar PO2 is found from the alveolar gas equation: PAO2 PIO2 - PACO2R We can assume that the inspired PO2 is the sea level normal value of 149 mm Hg. Therefore, neglecting the small correction factor, the alveolar PO2 is 149 - 201 or 129 mm Hg. Thus the alveolar-aerial PO2 diffusion is 129 - 90 39 mm Hg. The PCO2 of 20 mm Hg means that the patient is hyperventilating. The combination of the low PCO2 and low pH means that plasma bicarbonate concentration is reduced. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. 2012. Chapter 35. Gas Transpo pH. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks Eds,Ganongs Review of Medical Physiology, 24e. 