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S64 CLINICAL VALIDATION OF THE SEVERINGHAUS OXYGEN DISSOCIATION CURVE
J-A Collins, A Rudenski, BR O’Driscoll. Salford Royal University Hospital, Salford, UK
Background: Severinghaus has described a widely used mathematical model to calculate the oxygen dissociation curve for human blood. (J Appl Physiol 1979;46:599). This model is based on the results of laboratory tests using blood from a limited number of volunteers, which was adjusted to various predetermined oxygen tensions in vitro. We are unaware of any validation of the oxygen dissociation curve using blood samples from seriously ill patients with a wide range of oxygen tension values.
Methods: We audited 3524 anonymised blood gas results from patients treated at this university hospital (2255 specimens with normal pH (7.35–7.45), 558 acidotic specimens with pH <7.35 and 711 alkalotic specimens with pH >7.45). For each blood gas specimen, the oxygen saturation obtained by the laboratory co-oximeter was compared with the calculated value derived from the Severinghaus equation.
Results: The mean SaO2 was 94.98% (SD 5.9%) using the laboratory co-oximeter and 94.82% (SD 5.3%) using the Severinghaus equation. The mean difference was only 0.16%, which is not clinically relevant. The raw clinical data are shown in panel A of the figure and the Severinghaus curve is shown in panel B. Panel C shows that the mean of the clinical values is almost identical to the Severinghaus result throughout the clinically relevant saturation range at normal pH. Panel D shows the effect of pH on clinical specimens, confirming the Bohr effect of rightward shift with acidosis and leftward shift with alkalosis.
Conclusion: The mathematical equation of Severinghaus predicts the oxygen saturation of human blood from patients with a range of diseases with remarkable precision. We believe this to be the first large-scale clinical validation of this equation.
S65 INSULIN STIMULATES GLUCOSE UPTAKE AND GLUCOSE TRANSPORTER EXPRESSION IN H441 HUMAN AIRWAY EPITHELIAL CELLS
M Asaria, KK Kalsi, EH Baker, DL Baines. St George’s, University of London, …