JOURNAL and I will not discuss the various factors involved. It can be said, however, without fear of contradiction, that, provided ventilation is distributed evenly throughout the lungs and alveoli, an increase in lung volume can in no way impair haemorespiratory exchange. Increase in lung volume could only diminish the fluctuation in the concentration of alveolar gases which occurs during inspiration and expiration. The simile of the large and small room is fallacious, for if you have the same number of people in the small room as in the large room, and the same amount of air used for ventilation, there will be no significant difference in the atmosphere of the two rooms. In any case, increase in lung volume when it occurs is essentially due to increase in the size of individual lobules, and, as I have already stated, diffusion alone could maintain adequate gaseous exchange in a lobule much larger than the average size in emphysema.(g) An increase in the respiratory dead space has been suggested as the cause of impaired haemo-respiratory exchange, but there is ample evidence that any increase in the anatomical dead space-i.e., the space occupied by the respiratory passages down to the bronchioles-is too small to be of practical significance (Hoover and Gammon, 1915). I will not enter into a discussion on the meaning of the physiological dead space. Most physiologists will agree that those who claim an increase in physiological dead space in emphysema are merely stating in a complicated way that the distribution of ventilation is unequal. In the normal individual the distribution of ventilation is remarkably even throughout the lungs, and consequently samples of alveolar air taken after expirations of varying depths are more or less uniform in composition. This is not the case in severe ejnphysema: the deeper the patient expires the higher is the CO2 content and the lower is the 02 content of the "alveolar air," and these patients show the apparent paradox that, although the amount of air inspired is normal or even increased, the alveoli are under-ventilated. That part of these lectures which deals with the analysis and interpretation of these observations is distussed elsewhere; the conclusion which has been drawn from them is that much of the inspired air is deflected to the enlarged air sacs and bullae, the walls of which are avascular and which are therefore not in contact with the pulmonary circulation. The employment of pregnant women has become of vital importance at the present time, and we think it will be of interest if we record our experience in a factory concerned with a specialized industry (light engineering) in which an ante-natal clinic has been established to supervise women employees. It is realized that the figures are small, but we feel that the time has come for a very careful investigation into all factors connected with pregnancy among industrial workers. To obtain sufficiently large figures from any one industry might take so long that much of the value of the ultimate findings would ha...
Lynda Bourne explains how reiki works and how it may be useful as a complementary therapy in general practice
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.