Diffusing Capacity and Barometric Pressure Adjusted for Altitude

altitude adjusted diffusing capacity =

= (measured capacity) * (1.0 + (0.0031 * ((alveolar PO2) - 120)))

=  (measured capacity) * (1.0 + (0.0031 * ((0.21 * (Pbar -47)) - 150)))

where:

• 150 mm Hg is the inspired oxygen pressure at sea level

• Pbar = barometric pressure at the altitude

• Diffusing capacity is reported in mL of CO (at STPD) per minute per mm Hg.

If the barometric pressure is not known, it can be estimated as

barometric pressure in mm Hg =

= 760 * ((1 - (0.000006873 * (altitude above sea level in feet))) ^ 5.256)