title: A single-breath method of alveolar O2 determination.
abstract: We designed a single-breath method of alveolar O2 determination, requiring only a single tidal breath expirate and concomitant arterial blood sample. The PAO2 equation used in our method was derived by applying the Bohr equation to both O2 and CO2 and independant of VO2, VCO2 and RQ. In 35 patients with different degrees of airway obstruction, at rest and during exercise, the single-breath method agreed well with the classic method of PAO2 determination which required 3 min of expired gas collection and derivation of VO2, VCO2 and RQ. The mean difference between the PAO2 estimates by the two methods was 0.36 mm Hg as calculated for all patients, both at rest and during exercise. At rest, in 2 out of 35 cases the difference was greater than 2 mm Hg and such difference happened only in 1 case during exercise. A good correlation existed between the two PAO2 estimates by the two methods (r ranging from 0.977 to 0.996). The data indicated that single-breath method of PAO2 determination was reliable. Its extreme simplicity would facilitate greatly the assessment of gas exchange efficiency in situations where both patient's cooperation and laborator equipment are less than optimum.
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D005082:Physical Exertion; D011650:Pulmonary Alveoli / Q000502:physiology; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods*
chemical_list: D010100:Oxygen