Rahn and Otis (1) have described the normal changes in the alveolar gases during work and demonstrated the quantitative relationships between alveolar oxygen, carbon dioxide, respiratory quotient and ventilation by means of continuous recording of gas analyses. They were able to delineate the pathways of change which are controlled by the excretion of carbon dioxide, and observe the effects of hyperpnea, hypoxia, hypoventilation and CO2 breathing as well. Pelnar (2), at first independently and later in conjunction with Rahn, observed the changes in expired air composition in normal subjects as well as in patients with cardiorespiratory impairment in relation to work. By means of a simple diagram relating the changes in 02 and CO2 content of expired air with the respiratory quotient during the stress of exercise, he felt that he could delineate respiratory function better than by any other means in a manner that paralleled the intensity of dyspnea in patients. Between the extremes of a) normal performance with a large circular curve and b) the abnormal performance with no change in these values during exercise, Pelnar found a series of results which were characteristic of the varied stages of dyspnea. view that the level of ventilation is controlled in large measure by the CO2 when breathing normal ambient air in which the strong stimulus of hypoxia is lacking. The hypoxic stimulus of breathing 15%o oxygen in normals or hypoxemia from pulmonary disease in patients clearly induces greater ventilation levels, however.With these considerations in mind we have attempted to repeat these studies in both normal subjects and patients with disease to ascertain not only the normal respiratory pathways, but also the circulatory pathways during exercise and recovery. Thus the inter-relationships between the two can be considered in a way to demonstrate how the adaptations of each complement and spare the other. The techniques employed consist essentially of controlled work-loads by means of walking on a motor-driven treadmill and continuous gas analyses of expired air as well as determinations of electrocardiographic changes in rate and pattern, blood pressure and arterial oxygen saturation (oximeter) (Figure 1). Observations have not been limited to the basal state in order to obtain an appraisal of performance to a standardized stress of exercise in relation to ordinary circumstances in regard to diet, clothing and activity. In a separate report the statistical analyses of varial)ility of normal performances under these conditions is presented (4). For the purpose of defining the normal pathways in this report, only the mean values of all pertinent observations obtained at minute intervals before, during, and after exercise are graphically considered in relation to each other. METHODS

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.The influence of pregnancy on pulmonary function has been reported by many workers. While some investigators found that pregnancy has little effect on overall respiratory function, others felt that such factors as the gradual abdominal distension, the enlarged breasts, and the inherent circulatory changes do indeed affect the respiratory physiology in the pregnant woman. In the chronically ill patient, it is even more difficult to overlook the progression of respiratory symptoms and the diminution of cardiac reserve during the second half of pregnancy and during the early post-partum period. Part of the problem becomes evident when one notes that there have been only a few reports of serial pulmonary function studies in normal pregnant women as well as in pregnant patients with cardiopulmonary disease. This paper reports the studies of pulmonary function in 8 normal women and 16 patients with various cardiopulmonary diseases during each of the three trimesters of pregnancy and 10 weeks after delivery. Special attention is focused on changes in pulmonary diffusing capacity and pulmonary capillary blood volume. METHODS OF STUDYIn eight normal women and 16 patients, pulmonary function tests were studied during the first (10th week), the second (24th week), and the third (36th week) trimesters of pregn.ancy and 10 weeks after delivery. The data obtained 10 weeks after delivery were considered as the control values. In all patients radiographs of the chest with shielded abdomen, and electrocard...

In the preceding report (1) the complementary adaptations of respiration and circulation to the stress of exercise in normal subjects were described. Various isolated measurements, obtained by a method of continuous observation, were found to be in accord with those reported by earlier investigators employing the established TissotHaldane techniques of respiratory gas analysis. Because of the continuity of observation, various rates of change in adapting from a state of rest to a standardized stress of exercise (treadmill walking) as well as rates of recovery could be observed in relation to each other as loops of cardio-respiratory responses. These respiratory and circulatory pathways portray the representative responses in normal subjects, but a survey of the range of variability in normals and patients is needed before these pathways can be utilized properly for the study of impaired functions in patients with cardiorespiratory diseases. Pelnar (2) has critically reviewed the existing methods of functional appraisal of the causes of dyspnea in patients and expressed the opinion that his new method based upon the continuous study of the R.Q. curve during rest, exercise and recovery provides a more satisfactory appraisal of function in relation to dyspnea than any other method previously avail- 1431

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The hemodynamic effects of butorphanol, a potent synthetic narcotic-antagonist analgesic, were investigated and compared with those of morphine. A total of 20 patients were studied (8 butorphanol, 12 morphine) at the time of diagnostic cardiac catheterization. Butorphanol decreased pH, PCO2, and systemic artery pressure and increased PCO2, cardiac index, and pulmonary artery pressure. Morphine caused similar changes in pH, PO2, systemic artery pressure, and PCO2 but much smaller changes in cardiac index and no change in pulmonary artery pressure. The clinical implications and possible mechanisms are discussed.

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