Pulse oximetry: what the nurse needs to know

Rationale and key points Measurement of peripheral oxygen saturation (SpO₂) is used to identify early hypoxia in patients and evaluate the effectiveness of oxygen therapy. Nurses should be aware of the procedure for using a pulse oximeter to measure SpO₂ levels and the normal range for SpO₂ readings. » A pulse oximeter is used to measure SpO₂ levels, and involves placing a probe on the patient's finger, toe or ear lobe. » A SpO₂ level of less than 90% is a clinical emergency. If the SpO₂ level is below 94%, the nurse should assume the patient is hypoxic until proven otherwise, and therefore they may require supplemental oxygen administration. » Nurses should be aware of the factors that might affect SpO₂ readings, including anaemia, peripheral vasoconstriction, dark skin tone and skin discolouration.