Effect of preeclampsia on carboxyhemoglobin levels: a mechanism for a decrease in P50

: COHb levels were measured in 15 preeclamptic pregnant women and 15 normal pregnant women to investigate the cause for the decrease in P50 associated with preeclampsia. The authors also included six normal and six preeclamptic pregnant patients from the above groups in the determination of P50. Measurements of COHb levels were performed in a Radiometer OSM2 Hemoximeter. Determination of P50 was done using an IL 237 Tonometer, a Radiometer, OSM2 Hemoximeter, and a Corning 168 pH/Blood Gas Analyzer. Preeclamptic pregnant patients had a mean COHb level of 2.8%, whereas normal pregnant women had a mean COHb level of 0.7% (P less than 0.001). Preeclamptic patients also had a significantly lower (24.4 mmHg) P50 than normal pregnant women (P50 = 30.1 mmHg) (P less than 0.001). The authors conclude that a significant elevation of COHb in preeclamptic pregnant women is partly responsible for a significant decrease in P50 seen in preeclampsia.