A comparison of methods of obtaining alveolar air / Walter M. Boothby, M.D., and Francis W. Peabody, M.D. Boston.

  • Boothby, Walter M.
Date:
1914
Catalogue details

Licence: In copyright

Credit: A comparison of methods of obtaining alveolar air / Walter M. Boothby, M.D., and Francis W. Peabody, M.D. Boston. Source: Wellcome Collection.

    11/16 (page 9)
    tion. The results very frequently agree within 1 mm. tension of carbon dioxid. Almost always they agree within about 2 mm. tension. While this is perhaps not the highest degree of accuracy, it must be remem¬ bered that it is extremely difficult to achieve greater accuracy in obtaining samples of alveolar air by any method except in trained subjects, so that on the whole the results are satisfactory as far as their constancy is con¬ cerned. A series of observations has also been made comparing those obtained by the Plesch method with those obtained by the Haldane method in the same subject and at the same time. The relation is, of course, a variable one, but the Plesch method almost always gives a higher value for carbon dioxid tension. On the average it is approxi¬ mately from 1 to 4 mm. higher, but sometimes it is less and sometimes a little more. The advantages in the use of the Plesch method are obvious. From the point of view of the subject it is extremely simple, and satisfactory results can be obtained from almost any one with a minimum of training. It is frequently extremely difficult to make a sick person or, in fact, many healthy persons, give an expiration of maximum depth, but almost any one can easily breathe deep enough to give reliable results by the Plesch method. Moreover, the technic required of the observer is so simplified that it is readily acquired and needs very little skill. The chief disadvantage of the Plesch method is that it is not quite so accurate as the Haldane method. This, however, seems to be only with regard to highly trained subjects. In a person of experience and intelligence it is possible to obtain constant and accurate results by the Haldane method, but in the average run of persons the results obtained by the Plesch method are on the whole more satisfactory. The Plesch method is worked out on a more empirical basis, but it gives very constant values, and values which are extremely satisfactory for comparative studies. SUMMAKY As a result of an extensive comparative study of various methods for obtaining the tension of gases in the alveolar air, with especial refer¬ ence to the use of these methods in clinical work, we have arrived at the following conclusion: The Haldane method gives results which approximate closely the average gaseous composition of the alveolar air. It is the most reliable and accurate method when used on intelligent and experienced subjects. The necessity, however, of obtaining very deep and very forcible expira¬ tions limits its usefulness when working with untrained or sick persons. The Lindhard method, and the modification of it described here, give values analogous to those of the Haldane method. The method has