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Evaluation of two methods to calculate p 50 from a single blood sample
Author(s) -
Ekeloef N. P.,
Eriksen J.,
Kancir C. B.
Publication year - 2001
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.2001.045005550.x
Subject(s) - medicine , hemoglobin , limits of agreement , venous blood , oxygen tension , arterial oxygen tension , mean difference , oxygen , oxygen saturation , anesthesia , blood gas analysis , surgery , nuclear medicine , confidence interval , chemistry , organic chemistry , lung
Background: The hemoglobin‐oxygen affinity is conveniently described as the oxygen tension at which the hemoglobin is 50% saturated ( p 50). We compared two methods of single‐point analysis for p 50 calculation, using clinical data. Methods: From patients submitted to anesthesia for major surgery, 114 arterial or venous blood samples were analyzed by using the Sigaard‐Andersen oxygen status algorithm ( p 50 OSA ) and Doyle’s method ( p 50 Doyle ) based on Hill’s equation. Results: The oxygen saturation and tension varied respectively between 0.64–0.96 and 3.8 kPa–11.0 kPa. A Bland‐Altman analysis showed a mean difference of 0.04 kPa (SD 0.12 kPa). The limits of agreement were −0.20 kPa and +0.28 kPa. Conclusions: The Siggaard‐Andersen oxygen status algorithm is presently the most clinically useful single‐point method of p 50 calculation.