Diagnosis of OSA

In order to diagnose Sleep Related Breathing Disorders, an overnight sleep study is required. There are different types of sleep study and they range according to the number of recordings that they make. The most simple sleep study is an overnight pulse oximetry, which measures SpO2 and heart rate during the night. If a patient has an apnoeic event during sleep, their blood oxygen will fall and this will be seen on the pulse oximeter. They will also have a ‘spike’ in heart rate at the end of the apnoea, which will also be seen on the pulse oximeter.

There are advantages and disadvantages of using each sleep study. Oximetry is cheap, and can confirm a diagnosis of severe Obstructive Sleep Apnoea where the signs and symptoms are characteristic of OSA. However it has significant rates of both false negatives and false positives. It cannot reliably distinguish between obstructive and central apnoea, which may be significant when managing patients with heart disease.

The diagnosis of OSA is typically obtained during one of three consultations; part of a routine evaluation of health, part of an evaluation of symptoms of OSA, or part of the evaluation of patients who are high risk for OSA (patients with obesity, congestive heart failure, atrial fibrillation, nocturnal cardiac arrhythmias, uncontrolled hypertension, type II diabetes, stroke, pulmonary hypertension, high risk drivers, pre-operative assessment for bariatric surgery).

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