What is the best method to determine hemoglobin oxygen saturation?

The best method to determine hemoglobin oxygen saturation is through polychromatic absorbance measurements of a whole-blood hemolysate. This approach utilizes the principle that different forms of hemoglobin absorb light at specific wavelengths; for example, oxyhemoglobin and deoxyhemoglobin have distinct absorbance spectra. By measuring absorbance across multiple wavelengths, the relative contributions of these forms can be accurately determined, allowing for a reliable calculation of oxygen saturation.

This method is advantageous because it provides immediate and direct readings, making it very useful in clinical settings. It effectively utilizes the mixed or whole blood samples and is well-established for this specific application, offering a comprehensive profile of hemoglobin’s oxygen-binding capacity.

In contrast, other methods may have limitations. For instance, near-infrared transcutaneous absorbance measurements often provide non-invasive methods for estimating oxygen saturation but can be influenced by factors like skin thickness and peripheral blood flow, which may affect accuracy. Treatment of whole blood with alkaline dithionite can reduce hemoglobin to methemoglobin, impeding the accurate assessment of oxygen saturation since it alters the hemoglobin form being measured. Similarly, relying on calculations involving partial pressure of oxygen (PO2) and total hemoglobin can lead to errors if the relationship between