Definitive Diagnosis of Sleep Apnoea
The gold standard for diagnosing sleep apnoea is in-laboratory polysomnography (PSG), which involves the simultaneous recording of multiple physiological signals during sleep, including electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), electrocardiography (ECG), and respiratory signals.
PSG is expensive, time-consuming, and not always accessible.
Electroencephalography (EEG)
EEG is employed to monitor brain activity and identify sleep stages, allowing for the detection of abnormal sleep patterns and disruptions associated with the disorder.
Electromyography (EMG)
EMG is used to measure muscle activity, specifically that of the chin and limb muscles, which helps in identifying periods of reduced muscle tone and abnormal muscle activity related to sleep apnoea events.
Electrooculography (EOG)
EOG is used to record eye movements, which assists in determining the different stages of sleep, particularly rapid eye movement (REM) sleep, during which sleep apnoea events may be more frequent or severe.
Electrocardiography (ECG)
ECG is used to monitor the heart's electrical activity during sleep, helping to identify any cardiac abnormalities or arrhythmias that may be associated with or exacerbated by sleep apnoea events.
Respiratory Signals
Respiratory signals are used to monitor airflow, respiratory effort, and oxygen saturation levels during sleep, which help detect episodes of apnoea or hypopnea and assess the severity of the sleep disorder.
Home sleep apnoea testing (HSAT)
HSAT has emerged as an alternative diagnostic tool, using portable monitors to record a limited number of physiological signals, primarily focused on respiratory parameters.
HSAT has been shown to be effective in diagnosing sleep apnoea in patients with a high pretest probability of moderate to severe OSA but may be less accurate in patients with mild OSA or CSA.
HSAT offers patients the convenience of undergoing the test in the comfort of their own homes, making it a more accessible and cost-effective option compared to in-laboratory polysomnography. However, HSAT may not capture the full range of sleep stages and related physiological signals, which could potentially lead to misdiagnosis or underestimation of sleep apnoea severity in some cases.