Blood volume studies in chronic obstructive non-specific lung disease: a comparison of the bronchitic and emphysematous patients.

Blood volume studies.-in chronic hypoxic lung disease have produced conflicting results. Some have demonstrated that the red cell volume-hypoxic relationship is similar to that in normal subjects, whereas others have found that it is subnormal. Plasma volume has not been shown to be related to hypoxia. To elucidate this further, 45 patients with chronic obstructive bronchitis were studied. They were on average hypoxic at rest and on exertion, but mean values of red cell volume, plasma volume, venous haematocrit, red cell count, and haemoglobin concentration were normal. Red cell volume was linearly related to the degree of hypoxia, but the response was subnormal. Arterial oxygen saturation rather than tension was the main determinant of red cell volume, and resting values correlated better than exercise values with red cell volume. The best correlations were obtained when red cell volume was expressed as a function of the lean body mass rather than the total body weight. Red cell volume was also linearly related to arterial Co tension. Plasma volume did not correlate with any of the blood gases. The subnormal poly-cythaemic response to hypoxia may have been caused partially by latent iron deficiency and chronic infection; but severe hypoxia, hypercapnia, and gastrointestinal bleeding were not aetiological factors. The importance of tissue hypoxia in the regulation of the erythropoietic response and the reasons why previous blood volume studies have produced conflicting results are discussed. There is general agreement that-red cell volume, but not plasma volume, is linearly correlated with the level of hypoxia in healthy-subjects living at Weil et al., 1968). Blood volume studies in chronic obstructive non-specific lung disease have produced conflicting results. Some workers have concluded that red cell volume is not consistently elevated in a quantitatively normal manner for the level of 1969). This subnormal response has been attributed in turn to severe hypoxia, hypercapnia, iron deficiency, chronic infection, and gastrointestinal bleeding. In contrast, others have demonstrated a normal red cell volume response to hypoxia in these patients Plasma volume is usually unrelated to hypoxia and tends to fall within the normal range, except for the studies of Shaw and Simp-son (1961) and Vanier et al. (1963), in which it was increased. This paper reports the blood volume findings in 45 patients with chronic bronchitis and emphy-sema; the results support those who maintain that a subnormal red cell volume response to hypoxia occurs in this condition, and that plasma volume …