A 50-year-old woman with severe resting hypoxia not amendable to high-flow oxygen supplementation

The differential diagnosis of hypoxia, non-amendable to supplemental oxygen in a stable patient mainly includes right to left pulmonary or cardiac shunt, or a haemoglobinopathy with altered oxygen affinity.Clinicians should be familiar with instances in which pulse oximetry is not reliable, including poor tissue perfusion, certain nail polish types and haemoglobinopathies, and should obtain arterial blood gas for accurate assessment.If haemoglobinopathy is suspected, it is advisable to perform arterial blood gas analysis using a multi-wavelength spectrometer for accurate assessment.Early performance of haemoglobin electrophoresis followed by mutational analysis will yield diagnosis and prevent further work-up.The clinical course of low-oxygen-affinity haemoglobinopathies is mild, and patients should not be denied necessary surgical interventions due to this condition.