VENTILATORY IMPAIRMENT AND HYPOXEMIA IN CHRONIC NONSPECIFIC LUNG-DISEASE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 12  (6) , 735-745
Abstract
The relation between arterial O2 tension at rest (PaO2) and ventilatory performance (VC [vital capacity] and FEV1.0 [forced expiratory volume in 1.0 min.]) was studied (198 determinations) in a group of 156 patients (11 females) aged 31-76 (mean 52.1) yr, with chronic non-specific lung disease (asthmatics not included). The average results were 72.7 mmHg for PaO2, 2.87 l for VC, 1.32 l for FEV1.0 and 44.9% for the FEV1.0/VC ratio. Ninety percent of the patients had ventilatory impairment (FEV1.0 < 81% predicted) and 2/3 had hypoxemia (PaO2 < 75 mmHg). The PaO2-spirometric variables linear correlation coefficients were of medium value (0.35 to 0.51), but highly significant due to the large number of observations. The correlation was high in patients with severe ventilatory defect (FEV1.0 < 40% predicted), weak in those with moderate (FEV1.0 41-60% predicted) and absent in those with minor or absent ventilatory impairment. With respect to the clinical type of obstructive disease, PaO2 and FEV1.0 showed a high correlation (r = 0.69) in bronchitics, a looser one (r = 0.45) in intermediate patients and no correlation for emphysema patients. The regression equation relating PaO2 and FEV1.0 (PaO2 = 64.4 + 5.9 .times. l) had too high a standard error of estimate (20% of the mean) to be of practical value.