Diagnosis: Functional hemoglobin
• Oxygen saturation (SO2) can range from 0 to 100% and is mathematically calculated using the following formula: So2 = oxyhemoglobin/(oxyhemoglobin + deoxyhemoglobin).
• Although SO2 is a measurement of functional hemoglobin (Hb) that is bound to O2, PO2 is more commonly used in assessing oxygen-binding capacity in the lungs.
• Decreased PO2 can be caused by decreased pulmonary ventilation, impaired gas exchange, or altered blood flow between the heart and lungs.
• Carboxyhemoglobin contains carbon monoxide (CO) bound to Hb; carbon monoxide has a much higher affinity for Hb than O2.
• Methemoglobin contains iron in its ferric (Fe3+), not ferrous (Fe2+), state and, therefore, cannot bind oxygen or carbon dioxide.
