Potential inaccuracies in chloride measurements in patients with severe metabolic acidosis

Abstract

Background. To address the cause(s) of the significant differences in chloride (Cl -) concentrations between point-of-care blood gas analyzers and central laboratory analyzers. Methods. Cl - concentrations measured simultaneously by a blood gas analyzer (ABL800 FLEX) and a central laboratory analyzer (Hitachi7600) were collected in patients with severe acidemia (pH < 7.20) (n = 32) and were examined for correlations between differences in Cl - and factors associated with the acid-base status. Cl - concentrations were measured with both analyzers for samples with different concentrations of lactate, inorganic phosphate, or bicarbonate (HCO 3 -). Results. The differences in Cl - concentrations were correlated with HCO 3 - concentrations (r = 0.72, P < 0.0001) and anion gap (r = 0.69, P < 0.0001). Only the addition of HCO 3 - proportionately increased Cl - levels measured by a Hitachi7600, but it did not affect those measured by an ABL800FLEX. Conclusion. Cl - measurements with some analyzers may be influenced by HCO 3 - concentrations, which could result in the observed discrepancies. © 2012 Tetsuya Makiishi et al.