Final answer:
Carboxyhemoglobin formation from CO binding to hemoglobin can lead to falsely high oxyhemoglobin saturation readings on pulse oximeters, presenting challenges in diagnosing and treating CO poisoning effectively.
Step-by-step explanation:
When carboxyhemoglobin is formed, it significantly impacts pulse oximetry readings. Pulse oximeters are designed to measure the saturation of oxyhemoglobin in the blood. However, carbon monoxide (CO) has a much higher affinity for hemoglobin compared to oxygen—about 200 times more. This causes the hemoglobin to bind preferentially to CO, forming carboxyhemoglobin, even if only small amounts of CO are present. As a result, tissue hypoxia occurs because the oxygen binding and releasing capacities of hemoglobin are reduced.
Clinically, high carboxyhemoglobin levels, from sources such as pollution or overexposure to traffic fumes, can be indicated by a cherry red color of the skin. Treatment involves administering high concentrations of O2 under high pressure to dissociate HbCO and form HbO2, allowing the body to expel CO. Nonetheless, since most pulse oximeters cannot differentiate between oxyhemoglobin and carboxyhemoglobin, they may give a falsely high reading of oxygen saturation in cases of CO poisoning.