EFFECTS OF INTRAVENOUS ESTROGENS ON PULMONARY DIFFUSING CAPACITY

Use of oral contraceptives in women with cystic fibrosis

Oral contraceptive pills (OCP) represent the most common contraceptive method among teenagers and young adults. Because many women with cystic fibrosis (CF) are now surviving into childbearing age and are at risk for the complications of pregnancy in CF, oral contraceptive use may be indicated. However, it has been suggested that OCP use by CF patients may be associated with deterioration in pulmonary function. Ten adolescent and young adult women with CF and moderate-to-severe obstructive lung disease were studied while taking a combination oral contraceptive pill (Ovral 28). No significant deterioration was found in clinical status or pulmonary function. Careful follow-up should nevertheless be continued to monitor for other adverse effects of oral contraceptive use in CF, such as cholelithiasis.

The respiratory response to pregnancy

The respiratory response to pregnancy appears to be largely mediated by the action of progesterone and, perhaps to a lesser extent, oestrogens, at least in the first and second trimesters. The mechanical effects of the gravid uterus cause relatively little change in pulmonary mechanics, although finer changes in airways function require further investigation. Dyspnoea during pregnancy is also probably hormone-mediated but the exact temporal relationship between hormone status, functional change and the development of symptoms is not yet clearly defined.

Pulmonary function during pregnancy in normal women and in patients with cardiopulmonary disease

Pulmonary function studies were carried out during pregnancy in 8 normal women, in 8 patients with valvular (either mitral or aortic) heart disease, and in 8 patients with chronic pulmonary disease (either emphysema or sarcoidosis). In healthy pregnant women, changes in lung volumes and maximal expiratory flow rates were not significant. Diffusing capacity tended to decrease associated with unchanged pulmonary capillary blood volume. In patients with valvular heart disease, ventilation and oxygen consumption increased toward the term. The patients with mitral valve lesions showed a significant decrease in diffusing capacity with an increase in pulmonary capillary blood volume. In patients wth emphysema, characteristic changes were increasing obstructive functional abnormalities associated with an increase in pulmonary diffusing capacity and pulmonary capillary blood volume. None of these patients, however, had clinical evidence of deterioration of their disease. Patients with sarcoidosis had no appreciable alteration in pulmonary function tests.

The influence of various factors, such as increased ovarian hormones, ventilation-perfusion relationships, intra-abdominal distension, and cardiac haemodynamics, are discussed in relation to the change in pulmonary diffusing capacity and pulmonary capillary blood volume. From the standpoint of pulmonary function studies we think that patients with mitral heart disease and those with pulmonary emphysema tolerate pregnancy less favourably than normal subjects and patients with sarcoidosis.

Effect of sex hormones on the serum-induced thrombosis phenomenon

The renal veins of Sprague-Dawley rats were ligated following intravenous infusion of various dilutions of pooled dog sera. Ten minutes later, the occluded venous segment in each animal was opened, and the presence or absence of a clot was observed. After injection of saline, no clot developed. For each pool of dog sera, a "minimal thrombosis-inducing dose" (MTD) was established. This dose was about ten times higher in females than in males; castration of females reduced it to approximately the male level. Treatment of castrated females with Premarin (a conjugated estrogen preparation) returned the dose to the normal female range. Testosterone treatment of normal females reduced the dose, but to a somewhat less extent than did castration. Endocrine manipulation had little effect on the minimal thrombosis-inducing dose of males. The results obtained in this study appear to be relevant to epidemiological data in human populations, an indication that primary artery thrombosis (coronary occlusion, cerebrovascular accident) is less common in women during the reproductive ages than in men; but after the menopause, the incidence rapidly increases in the female population.