non-invasive multi wavelengths sensorsystem for measuring carboxy-and methemoglobin

Standard pulse oximetry only measures the functional derivatives oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) to calculate the arterial oxygenation. However, the two dysfunctional hemoglobin derivatives carboxyhemoglobin (COHb) and methemoglobin (MetHb) are of much interest. The gold standard detecting abnormal concentration of COHb or MetHb is the blood gas analysis (BGA). In this paper a non-invasive method for measuring these derivatives and a setup for validation is presented.