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. 87 INTRODUCTION Carboxyhemoglobin (HbCO) saturation in a liquid specimen collected from a significantly putrefied or markedly burnt cadaver is not infrequently analyzed in medicolegal practice. Spectrophotometry has been widely used for the determination of HbCO in fresh blood and blood denatured by putrefaction or heat, because of its simplicity, rapidity and reliability. However, it has not been confirmed that spectrophotometry yields correct values in the detetmination of HbCO saturation in the case of significantly putrefied blood, blood markedly denatured by heat, or body cavity fluids. So, the HbCO saturation in a liquid specimen collected at medicolegal autopsy was analyzed by a spectrophotometric method [developed by Fretwurst et al. t), modified by Fukui2) and then modified by authors7)] and compared with that analyzed by a carbon monoxide-total hemoglobin (CO-Total Hb) method developed by authors4• s). The results indicate that spectrophotometry should not be used for the quantitative determination of HbCO in body cavity fluids, blood mixed with body cavity fluid, markedly putrefied blood, or blood considerably denatured by heat. MATERIALS The liquid specimens used were blood collected at medicolegal autopsies from the heart or blood vessels, and body cavity fluids from thoracic, pericardia! and abdominal cavities of cadavers deceased by fire, drowning or other causes. Seventy blood specimens were collected from 59 cases. They were classified according to the time elapsed between death and collection of the specimen, and degree of burn on the body