Should oxygen saturation be included in the vital signs sheet of all medical admissions?

Hypoxaemia is not uncommon in hospitalised patients and may be overlooked because cyanosis is a late sign. To estimate the incidence of undetected hypoxaemia we measured oxygen saturation (SpO2) by pulse oximetry randomly in medical patients who were not receiving supplemental oxygen in a teaching hospital and a community hospital. Of 580 patients studied, nine patients (1.55%) had SpO2 <92%. All nine patients had multiple morbidities, but all had cardiopulmonary disease in common. There was no significant difference between the teaching and the community hospitals. We conclude that undetected hypoxaemia is not common in patients on the medical wards, and that routine pulse oximetry is not necessary except for patients with known cardiopulmonary disease.