Arthur B. DuBois

Effect of removal of bullae on airway conductance and conductance volume ratios

Airway conductance is known to increase with an increase in the lung volume at which it is measured, owing to a change in transpulmonary pressure and lung tissue tension. We investigated the effect of surgical resection of lung tissue on functional residual capacity and airway conductance in patients with localized lung disease (i.e., carcinoma or tuberculosis) and in patients with lung cysts or bullous emphysema. In four out of five of the patients who had resection of one or more lobes of the lung to remove localized disease there was a reduction both in the airway conductance and in the functional residual capacity with relatively little change in the conductance volume ratio. By contrast, in all patients who underwent bullectomy, there was a decrease in functional residual capacity but an increase in airway conductance, and an increase in the conductance/volume ratio. This change was sustained in patients who had had localized cysts removed. However, the measurements gradually reverted toward preoperative values in those patients who had generalized emphysema. The increase in airway conductance after resection of blebs and bullae presumably was due to improved lung elastic pressure causing the airways to increase in diameter and conductance. In addition, some patients may have experienced relief of compression of neighboring airways.

Respiratory factors determining the tissue concentrations of inhaled toxic substances

Abstract The respiratory factors which may affect the concentration of inhaled toxic substances in the body tissues and deeper layers of the bronchial epithelium are analyzed theoretically. Representative examples are calculated using equations for tissue diffusion and bloodflow. The conclusions are that respiratory factors are not important after long periods of inhalation because of equilibration, unless the composition of the inhaled substance is extensively altered in the tissues. The deeper layers of epithelial tissue in the smaller bronchi are most subject to development of high concentrations when exposure is of short duration.

Pulmonary function in premature lambs during the first few hours of life

This study establishes the mean values, variations, and trend of pulmonary function during the first few hours of life in premature lambs. Measurements of intraesophaheal and tracheal pressure, air flow, tidal volume, and functional residual capacity enabled calculations of lung compliance, specific lung compliance, and inspiratory and expiratory resistance of the lungs. Arterial carbon dioxide tension and pH were maintained within a physiologic range. Mean arterial oxygen tension (PO2) at elevated inspired oxygen tension, varied in the individual animals from 51 to 185 mm Hg at an inspired oxygen concentration of 46 to 71%. It was found that the lungs of premature lambs delivered by cesarean section were mechanically unstable; the lambs were all ineffectual at breathing and required some form of mechanical ventilation. During the first 6 hours of postnatal life the lungs of premature lambs are characterized by a wide range of mechanical values and blood gas tensions.

THE RATE OF INTRAPULMONARY BLOOD GAS EXCHANGE IN LIVING ANIMALS

The respiratory function of the blood depends on a series of reversible reactions of oxygen and carbon dioxide with blood. The optimal performance of this function requires that the rate of these reactions be such as to permit them to approach completion within the time the blood spends in the vessels of gas exchange. In the case of carbon dioxide, experiments by Roughton (1) and more recently by Forster (2), using different methods, have suggested that the reactions involved may be slow enough to limit the excretion of CO2 in the lung. Most of the work in this field has been performed in vitro, and because of the difficulty in carrying over the information obtained to living systems, we have devised a technique by which some aspects of the reactions leading to CO2 liberation in the lung can be studied in living animals.

The Forces Resisting Locomotion in Bluefish

Swimming in nature may have played a major role in the gradual evolution of the form and function required by present land vertebrates. The reasons behind this conclusion are developed below.

The Nature of Dynamics of Cellular Carbon Dioxide

My assignment was to discuss the paper by Dr. Chinard. Unfortunately, Dr. Chinard is not here. But for the last month I have been traveling through France and looking at monuments such as cathedrals, limestone caves, and bones, and began to suspect that they might have something to do with CO2. The cathedral looked too smooth and white to be granite. I determined by scratching it with my fingernail that the cathedral was a soft material more likely to be calcium carbonate. The limestone caves had been eroded by water with CO2 dissolved in it, and the bones were obviously composed largely of CO2, the sole remains of our ancestors of long ago. So I have really been looking at a large pool of CO2 in France. We have been standing, sitting, walking, or living within structures built of CO2. This gets us back to “The nature of dynamics of cellular CO2.”