The value of spirometry as a first step in clinical assessment of pulmonary function has been previously outlined.1 This presentation will concern itself primarily with the value of arterial blood gas measurements in caring for the acutely ill patient who is in the hospital with lung disease.
Methods of blood gas analysis have been comprehensively discussed recently2,3 and will receive only brief mention here. The Van Slyke manometric technique of measuring arterial O2 content and saturation (Sao2)1 remains a standard of reference in many research laboratories but is not very useful in clinical practice. Measurement of O2 saturation by the photoelectric reflectance method is adequate for clinical purposes. However, determination of arterial O2 tension (Pao2) by the Clark membrane-covered polarographic electrode often provides additional information. If in addition to the Po2, the pH and temperature are known, the O2