<prompt> At the altitude of 6500 meters, the atmospheric pressure is 347 Hg. What is the inspired PO2?73 mmHg63 mmHg53 mmHg83 mmHg  <response>: PO2 of the inspired air is 21 percent of ihe total barometric atmospheric pressure. Hence, 21100 347 72.87. Decreased ambient oxygen pressure results in hypoxemia. This is most commonly seen at high altitude or in nonobstructive asphyxia. The A-a O2 gradient is normal, and hypoxemia improves with supplemental oxygen. Ref: Sarko J., Stapczynski J.S. 2011. Chapter 65. Respiratory Distress. In J.E. Tintinalli, J.S. Stapczynski, D.M. Cline, O.J. Ma, R.K. Cydulka, G.D. Meckler Eds, Tintinallis Emergency Medicine: A Comprehensive Study Guide, 7e. 