Pulmonary capillary blood volume in women: normal values and the effect of oral contraceptives.

Pulmonary capillary blood volume (V0) was determined in 30 young women, 14 of whom were taking oral contraceptives. Duplicate estimates of V, in the 16 women not taking contraceptives showed a significant increase in the second half of the menstrual cycle. Formulae for prediction of V. in women were derived for the first and second halves of the cycle. V, was shown to be of the same order in women taking contraceptives containing oestrogen and progestogen as in those in the premenstrual phase of the cycle. Possible causes of these findings and their relevance to the diagnosis of pulmonary thromboembolic disease are discussed.