Carboxyhemoglobin as measured by gas chromatography and with the IL 282 and 482 CO-Oximeters

Abstract

We measured the concentration of carboxyhemoglobin (HbCO) in original and CO-tonometered blood samples from 53 intensive-care patients with IL 282 and IL 482 CO-Oximeters and by gas chromatography (GC), finding very strong correlations among the three methods for HbCO concentrations >2.5%. For concentrations within the normal reference interval (≤2.5%), however, the correlation between CO-Oximetry and GC is poor (r2 < 0.26). The capillary mode of the IL 482 has a consistently lower correlation with any other method or mode. The correlations of measurements between the CO-Oximeters for total hemoglobin and oxyhemoglobin were excellent (r2 ≥ 0.98). Correlations for methemoglobin were lower, owing to its low concentrations in the samples. We conclude that the IL 482 and IL 282 are analytically equivalent for all analytes measured, but that both instruments differentiate poorly between HbCO values that fall within the reference interval.