Changes in pulmonary diffusing capacity and blood gases in chronic obstructive lung diseases.

Pulmonary diffusing capacity (TLco) of 19 cases of chronic obstructive lung diseases (Chronic obstructive bronchitis and chronic obstructive emphysema) in the age group of 39 to 58 years (mean age: 49.8 +/- 5.5 SD years) are reported at rest in this investigation. The diffusing capacity for carbon monoxide (TLco) measured by standard methods was significantly reduced in all cases. The mean was 13.1 +/- 2.3 SD ml/min/mmHg. The blood gas findings revealed low arterial oxygen saturation (mean value: 90.2 +/- 2.2%). Arterial carbon dioxide tension was higher than in normal subjects. The mean for this series was 44.8 +/- 4.9 SD mmHg. The mean for normal subjects was 37.5 mmHg and the range 28.2 to 41.5.