BRUCE M. SMALL, M.S., M.D.
To the editor: The article by Lichtman, Murphy, and Adamson (Ann Intern Med 84:517-520, 1976) presents a useful technique for the detection of hemoglobins with altered oxygen affinity. However, the equation given for the determination of P50 from the observed oxygen tension, saturation, and pH is rather formidable and may be reduced in a few steps to:
AS REC P50std = antilog(logPO2 - (7.40 - pH)/2 + (1/n) (logR) ), where R = (100 - SO2)/SO2, and all other symbols are as defined by Lichtman and associates.
In this form the calculation is shortened somewhat, and also the contributions to
SMALL BM. Hemoglobins with Altered Oxygen Affinity. Ann Intern Med. ;85:255. doi: 10.7326/0003-4819-85-2-255_1
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Published: Ann Intern Med. 1976;85(2):255.
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