A practical method for determining the amount of blood passing over during direct transfusion / E. Libman and R. Ottenberg.

  • Libman, Emanuel, 1872-1946.
Date:
1914
Catalogue details

Licence: In copyright

Credit: A practical method for determining the amount of blood passing over during direct transfusion / E. Libman and R. Ottenberg. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    4/14 (page 2)
    .«pite of the transfer of a considerable amount of blood. The variations in the pnlse-rate of either donor or patient are likewise too irregular and too subject to ilisturbance from psycliic causes to be of help. The rise in the percentace of hemoglobin, on the other band, when the patient’s hemoglobin is low at the start of the transfusion, is a phenomenon which occurs with great regularity and is susceptible of very accurate measurement. In fact, for three years before the method of calculation to be described was followed, wo and others used the hemoglobin rise as a rough guide in the course of transfusion. The question, however, of how liigh the hemoglobin can be raised in a given case, can- not be answered, except by ])recise calculation. The principle on which our method of calculation is based is a sini))lc arithmetical calcnlation. If two fluids, liaving dilTerent percentages of any substance in solu- tion are mixed in unequal volnines. the percentage strength of the resulting mixture is the sum of the products of volume multiplied by the j)crcentage of each solution, divided by the volume of the total mixture, 'riiiis, if one volume of a jO per cent, solution is mi.xed witli two volumes of a 100 per cent, solution, the percen- tage strength of the resulting solution uill be; (1 X-'>0» -I- (2X10(0 — =83.a JXT cent. l-f-2 In order to calculate the exact amount of blood, and not merely the relative volume transfused, it is neces- sary to know the blood volume of donor and patient. As blood volume, even in health, undergoes slight varia- tion, and there is at present no practical method for accurate determination of blood volume, it is impossible at present to know the blood volume in each instance with great accuracy. Nevertheless, a large number of experimental observations by various authors have shown that blood volume bears a rather constant relation to body-weight. The conclusions of different authors on this subject do not all agree; but from a large number of accurate determinations by various methods it has recently become clear that the original estimate of Wclcker in 1858, accepted for manv years—that human blood-weight is approximately one-thirteenth of the body- weislit — is wrong, and that the actual proportion of