Factors affecting the loss of carbon monoxide from stored blood samples.

The loss of carbon monoxide (CO) from whole blood or hemolysates has been investigated. Blood samples were exposed to the atmosphere or to a limited volume of air for various storage periods at three temperatures. The initial hemoglobin (Hb) concentration and the percent carboxyhemoglobin (%COHb) saturation were varied in separate experiments. In addition, the effect of repeated exposure of blood to air was evaluated. The %COHb saturation decreased from 80 to 50% following storage of a 1-mL blood sample with 49 mL of air in a sealed container at room temperature for 45 hr. Greater decreases in the %COHb saturation were observed in samples which were exposed to the atmosphere. Lesser, but significant, losses occurred when samples were stored in a refrigerator or freezer. The concentration of Hb in the samples as well as the initial %COHb saturation were found to influence the decrease in the %COHb saturation.