Arterial to end-tidal CO2 difference in respiratory disease.
The difference in CO2 tension between arterial blood and end-tidal alveolar gas (a-end-tidal)DCO2 was found to correlate fairly well with the VD/VT ratio in 13 healthy subjects and 50 patients with pulmonary diseases (r = 0.74), and to discriminate between healthy subjects and patient groups at least as effectively as did the VD/VT ratio. An increase in breathing frequency from 8 to 32/min, without simultaneous change in alveolar ventilation, was associated with a mean increase in (a-end-tidal) DCO2 of several mmHg in both the healthy subjects and the patient groups. It is concluded that measurement of (a-end-tidal)DCO2 seems to be a clinically useful alternative to measurement of VD/VT ratio for evaluation of the wasted ventilation component, provided that the effect of the breathing frequency on (a-end-tidal) DCO2 is taken into account.
D000328:Adult; D002245:Carbon Dioxide / Q000097:blood* / Q000378:metabolism; D005541:Forced Expiratory Volume; D006801:Humans; D008171:Lung Diseases / Q000503:physiopathology*; D008297:Male; D010313:Partial Pressure; D011650:Pulmonary Alveoli / Q000503:physiopathology*; D012126:Respiratory Dead Space; D012129:Respiratory Function Tests; D013147:Spirometry; D013990:Tidal Volume; D014797:Vital Capacity
D002245:Carbon Dioxide