APStracts 2:0438A, 1995.

The effect of measurement error on calculated variables of oxygen transport. Woda, Russell P., Roger R. Dzwonczyk, James P. Orlowski, Frederick Van Lente, Lawrence A. Lynn. The Ohio State University, Department of Anesthesiology, Critical Care Medicine, N416 Doan Hall, 410 West Tenth Avenue, Columbus, Ohio 43210, University Community Hospital, Pediatrics Intensive Care Unit, Tampa, Florida, The Cleveland Clinic Foundation, Department of Clinical Pathology, Cleveland, Ohio, Doctor's Hospital, Division of Pulmonary Medicine, Columbus, Ohio

APStracts 2:0438A, 1995.

The effect of measurement error in pH, PCO2, and PO2 on mathematically derived variables of oxygen transport in patients was delineated by comparing calculated oxygen saturations from a blood-gas machine with measured saturations from a co-oximeter and further by modeling the error in a computer simulation. Twenty-one critically ill patients aged 30 - 84 years were studied. A total of 80 arterial and 80 mixed venous blood gas samples were collected. The intraclass correlation results between measured and calculated arterial (SaO2) and mixed venous (SO2) oxygen saturations were 0.59 and 0.68 respectively. The product moment correlation for SaO2 was 0.75 and for SO2 was 0.77. The percent error in calculating and measuring SO2 was found to be greater at low PO2 values while percent error of calculating O2 increased as the partial pressure of oxygen increased. Measurement repeatability at high PO2 is better than at low PO2 for both measured and calculated methods. We conclude from this comparison that measured and calculated arterial and mixed venous oxygen saturations are not interchangeable. Each can introduce substantial error in calculating oxygen consumption through error propagation and error amplification.

Received 7 February 1995; accepted in final form 2 October 1995.
APS Manuscript Number A146-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95