Pulse oximetry in patients with pigmented skin: What I should know

Pulse oximetry is widely used to non-invasively estimate the oxygen saturation of haemoglobin in arterial blood (SpO₂). It is used widely throughout healthcare and was used extensively during the Covid-19 pandemic to detect and treat hypoxic patients. Research has suggested that pulse oximetry is less accurate in patients with darker skin. This led the US Food and Drug Administration agency (FDA) to issue a safety statement warning that pulse oximeters may be inaccurate when patients have pigmented skin. Evidence suggests that the oxygen saturation of arterial blood (SaO₂) may be being overestimated by measuring SpO₂ in those with pigmented skin. The degree of overestimation increases as SaO₂ decreases especially when SpO₂ reads below 80%. We review how pulse oximetry works and consider the implications for a patient's health when interpreting SpO₂ in individuals with pigmented skin.