What is the minimum SpO2 percentage an oximeter would accurately read for a patient with good percussion?

An oximeter measures the oxygen saturation of arterial blood (SpO2) by using light absorption characteristics of hemoglobin at different wavelengths. The accuracy of oximeter readings can be influenced by multiple factors, including the patient's perfusion status. In patients with good perfusion, the oximeter can often provide reliable readings down to around 70%. Below this level, the reliability and accuracy of the readings can decrease significantly due to limitations in the device's ability to detect adequate blood flow and oxygen content.

While some oximeters may start to read at lower levels, a reading of 70% is generally accepted as the minimum threshold for reliable SpO2 readings in clinical practice. At this saturation level, hemoglobin is still sufficiently present to allow for working measurements, which assists in assessing a patient's respiratory and cardiac health. Thus, the choice of 70% as the correct answer reflects a standard understanding of the capabilities and limitations of pulse oximetry, particularly when considering patients who are otherwise stable with good perfusion.