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Abstract
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This discussion will be mostly confined to certain sections of Dr. Rabinowitch's paper which deal with questions that have been rather extensively studied in our laboratory.
1. Plasma vs. Whole Blood (p. 229), and Serum Alcohol (p. 229). If Dr. Rabinowitch will pursue his suggestion regarding the relationship of alcohol per cent and water content of body tissues and fluids and will calculate the alcohol concentrations in these materials, based on water content per unit vol?mne, he will find the differences to be much less than he assumes. With average human blood (1, 2) the serum, or plasma, has a specific gravity of 1.027 and a water content of 90.7 per cent by weight, while whole blood has a specific gravity of 1.055 and 79.1 per cent of water by weight. This means that each 100 cc. of plasma or serum contains about 93.1 cc. of water, and that each 100 cc. of whole blood contains about 83.4 cc. of water. If the distribu- tion of alcohol follows the water content, this would mean that the concentration of alcohol per cc. of plasma or serum would be about 12.5 per cent higher than the concentration of alcohol per cc. of whole blood. Based on weight, the difference would be somewhat greater; however, in this country we measure sam- ples of body fluids by volume and not by weight, and the results are usually given as weight-volume and not weight-weight.
To support his view Dr. Rabinowitch cites papers by Elbel and Kunkele. Reference number 22 of his bibliography indicates that, for Kunkele's paper and probably also for the paper by Elbel, he did not read the original but depended upon a review article by McGrath (R's reference #6). Elbel analyzed serum and whole blood from ten drinking individuals, emjloying the Widmark method of analysis. He found serum/whole blood alcohol ratios of 1.05 to 1.25, with an average of 1.17. Thesej figures are based on milligrams of alcohol per unit weight of serum or whole blood. Since the specific gravity of whole blood is about 3 per cent higher than that of serum, Elbel's ratios, calculated on the basis of milligrams of alcohol per cc. of serum or whole blood, become 1.02 to 1.21, with an average of 1.135. Kunkele analyzed serum and clot from four samples of human blood. Prior to being analyzed, the clot was washed briefly with distilled water and quickly dried with filter paper. In spite of this treatment, ]Kunkele found the clot to contain from 82 to 88 (ave. 86) per cent of the alcohol found in an equal weight of serum. Since the cells have a specific gravity of 1.090 (1, 2) as compared with 1.027 for serum, Kunkele's results, recalculated as milligrams per cc., would give serum/clot alcohol ratios of 1.07 to 1.15 with an average of 1.11. The clot usually represents about half the volume of whole blood, so this would mean an error of only 3 to 8 per cent if serum were substituted for whole blood. Kunkele further showed that longer washing of the clot resulted, as would be expected, in much lower alcohol concen- trations in it. It is not clear why he needed to wash the clot at all...
https://scholarlycommons.law.northwestern.edu/jclc/vol39/iss2/13
Keywords: Ethanol impaired driving
Language: en |