The oxygen tension of arterial blood / by John Haldane and J. Lorrain Smith.

  • John Scott Haldane
Date:
[1896]
Catalogue details

Licence: Public Domain Mark

Credit: The oxygen tension of arterial blood / by John Haldane and J. Lorrain Smith. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    not explain away Bohr’s main conclusions, since in several of his experiments the latter found that the carbonic acid tension in the air of the aerotonometer sank from a point higher than, to a point lower than, that of the expired air. In two experiments a corresponding, though slight, rise in the oxygen tension in the hsemataei’ometer over that in the expired air was also observed. It appears to us that there are serious reasons for doubting the correctness of the values for oxygen tension obtained either directly by the aerotonometer, or indirectly by means of the blood-pump. In 18G7 Pfliiger published1 a number of experiments in which he showed that arterial blood, especially if kept warm, immediately on leaving the body uses up part of its own oxygen. He observed that there is always a distinct darkening in the colour of arterial blood within a few seconds of its being shed. He also found that when blood was received straight from an artery into hot water in a very large vacuum (of 8 litres) instead of being pumped out in the ordinary way with a blood-pump possessing a 3 litre vacuum, the percentage by volume of oxygen obtained from the arterial blood was higher by from 0'2°/o to 10°/o—on an average l’98°/o- Hence on an average 9 °/o at least of the whole oxygen contained in arterial blood would seem to disappear very quickly after the blood leaves the body. This disappearance would account for a lowering in the oxygen teusion of the shed blood from 21 °/0 to about 3'5°/o of an atmosphere, according to Hiifner’s dissociation curve. Even if only 05 °/„ by volume of oxygen (i.e. 2 °/„ of the total quantity) had time to disappear before the blood passed through the aerotono- meter, the oxygen tension would be lowered from 21 °/0 to about 11 °/0. Some of Fredericq’s later experiments2 seem to afford strong confirmation to these suspicions. He found (experiment no. VII.) that when the animal was breathing a mixture containing 8T6 °/0 of oxygen, the oxygen tension of the arterial blood, as determined by the aerotono- meter, was nevertheless only 56'2 °/0 of an atmosphere. This is just such a result as might be expected on the supposition that the oxygen tension falls considerably between the artery and the aerotonometer. On the diffusion theory supported by Fredericq, one would expect the oxygen tension of the aerotonometer, if the latter indicated correctly, to be about equal to the alveolar oxygen tension. With the high per- centage of oxygen used by Fredericq oxygen would diffuse into the blood about 5 times as rapidly as usual, although the blood could only 1 Centralb. fur die med. Wissensch., 18G7, pp. 321, 722. 2 Centralb. fur Physiologic, 1894, p. 34.
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