James L. Whittenberger

Influence of Pulmonary Arterial and Left Atrial Pressures on Pulmonary Vascular Resistance

A method has been developed by which flow to each lung, as well as pulmonary artery and left atrial pressures can be measured and varied at will. Vascular resistances were determined over a wide range of these variables. Both pressures have a marked effect on vascular resistances; the higher either pressure, the lower the resistances. This effect is most marked at low levels of pressure and flow. The absolute levels of the pressures, by affecting vascular distension, are major determinants of pulmonary vascular resistance.

The Effect of Pulmonary Vascular Pressures on the Mechanical Properties of the Lungs of Anesthetized Dogs

Since the experiments of von Basch (1) it has been recognized that pulmonary vascular congestion influences the mechanical behavior of the lungs. A number of studies in patients with chronic congestive failure have demonstrated marked changes in pulmonary elasticity (2-6). It has not been possible to determine in such patients the relative contributions of pulmonary edema, other parenchymal changes, and vascular congestion per se to the observed changes. Experiments with acute congestion in man or living animals (7-10) and isolated lungs (11) have yielded conflicting results. The purpose of the present study was to examine in the living animal the effects of acute changes in pulmonary arterial and venous pressures and blood flow on the mechanical behavior of the lungs. The left atrial pressure and the pulmonary blood flow were varied independently. In one set of experiments, volume-pressure curves were obtained during stepwise inflation and deflation of the lung over a wide range of volume starting from the passively collapsed state. In another group, pulmonary compliance and flow-resistance were studied during continuous cycling of the lungs in the normal tidal range of lung volume.

Respiratory impairment in workers exposed to "safe" levels of toluene diisocyanate (TDI).

Workers in a factory producing polyurethane foam have been studied at six-month intervals for a period of 18 months. On each of the four surveys the forced expiratory volume in one second (FEV1) was determined on Monday morning and afternoon. The concentration of toluene diisocyanate (TDI) in air did not exceed 0.014 ppm on any occasion (multiple samples during each survey in all parts of the factory were taken). The exposed workers had reduction of ventilatory capacity at the afternoon measurement; the acute changes were not reversed overnight; cumulative changes exceeding those associated with aging occurred in these workers over 6, 12, and 18 months; symptomatic workers showed a greater response to TDI than asymptomatic ones; and a substantial positive correlation existed between the acute and cumulative changes in FEV1.

THE DIRECT EFFECTS OF PRESSURE BREATHING ON THE PULMONARY CIRCULATION

The effects of pressure breathing on the systemic and pulmonary circulations are of practical concern to the anesthesiologist because the technique of controlled respiration is so commonly employed. During World War I1 the contributions of physiologists interested in aviation medicine added greatly to our knowledge of the effects of positive airway pressure on the systemic circulation. The present discussion is concerned with a less well understood aspect of the problem : the direct effects of pressure breathing on the blood vessels within the lungs.

Role of Schools of Public Health

THE role of the graduate school of public health in the training of physicians has been a controversial one. The need for schools of public health has been questioned by some medical educators in r...