A new trend in blood gas chemistry: the measurement of clinically relevant hemoglobin derivatives. Performance of the OSM3 hemoximeter.

Supplementing the determination of total hemoglobin (CHb*) and oxygen saturation (SO2) with measuring the fractions (F) of inactive hemoglobins (dyshemoglobins: carboxyhemoglobin, HbCO; methemoglobin, Hi; sulfhemoglobin, SHb) in human blood is becoming common practice in many hospitals. We tested the performance of a new instrument for this purpose, the hemoximeter OSM3 (Radiometer, Copenhagen, Denmark) by comparing the results with those of an established multiwavelength method (MWM). For 100 fresh blood samples from patients with SO2 ranging between 20 and 100%, the difference between the two methods (OSM3-MWM) was 0.90% SO2 +/- 1.14% (SD). A series of 214 consecutive blood samples from patients with FHbCO ranging from 0 to 12% showed for HbCO a difference (OSM3-MWM) of 0.03% FHbCO +/- 0.47% (SD). In the same blood samples FHi was between 0 and 1.4%. The OSM3 gave a mean value of 0.81%, the MWM 0.47%. In order to put the OSM3 to a more severe test we made from normal human blood several series of specimens with high concentrations of dyshemoglobins. The difference between OSM3 and MWM was for 37 specimens of blood with 1-60% HbCO 0.29% FHbCO +/- 0.96% (SD), and for 34 specimens of blood with 0-70% Hi -0.29% FHi +/- 2.29%. For specimens with high fractions of HbCO and Hi the agreement between the SO2 measurement made with the two methods remained good, even when the dyshemoglobins were present in combination. Hi fractions of up to 70% did not interfere with the measurement of HbCO; the same holds good for the measurement of Hi in the presence of HbCO.