Selection of Specimen in the Determination of Carboxyhemoglobin Saturation by Spectrophotometry

Carboxyhemoglobin (HbCO) saturation in a liquid specimen collected at medicolegal autopsy was analyzed firstly by a spectrophotometric method, which was first reported by Fretwurst et al, modified by Fukui and then modified by the authors, and secondly by a carbon monoxide-total hemoglobin (CO-Total Hb) method developed by the authors. In 70 blood specimens collected from the heart or blood vessels of 59 cadavers, the values obtained by the spectrophotometric method were similar to those obtained by the CO-Total Hb method with the exception of three blood specimens, two of which were markedly putrefied and the other considerably denatured by heat, in which the values obtained by the spectrophotometric method were significantly higher than those by the CO-Total Hb method. In 62 specimens of reddish discolored body cavity fluids collected from 31 cadavers, nearly all values obtained by the spectrophotometric method were much higher than those obtained by the CO-Total Hb method. The results indicate that the spectrophotometric method should not be used for the quantitative determination of HbCO in body cavity fluids, blood mixed with body cavity fluid, or blood markedly denatured by putrefaction or heat.