From the Guidelines
Mixed sleep apnea is diagnosed when a patient exhibits both obstructive and central sleep apnea events during a single sleep study, with a significant proportion of both obstructive events and central events, and the diagnostic criteria include the presence of at least 5 respiratory events per hour of sleep (apnea-hypopnea index ≥ 5) as per the American Academy of Sleep Medicine guidelines 1. The diagnosis of mixed sleep apnea requires a comprehensive sleep evaluation, including overnight polysomnography, which monitors multiple physiological parameters such as airflow, respiratory effort, oxygen saturation, brain activity, and body position.
- The gold standard for diagnosis is overnight polysomnography, which can identify both obstructive and central sleep apnea events.
- The diagnostic criteria for mixed sleep apnea include the presence of at least 5 respiratory events per hour of sleep (apnea-hypopnea index ≥ 5), with a significant proportion of both obstructive events (where breathing effort continues against a blocked airway) and central events (where both airflow and breathing effort temporarily cease) 1.
- Treatment typically addresses both components, often starting with continuous positive airway pressure (CPAP) therapy at pressures between 5-20 cmH2O, which may need adjustment to an adaptive servo-ventilation (ASV) device if central events persist or worsen on CPAP, as recommended by the American Academy of Sleep Medicine 1.
- Mixed sleep apnea often emerges during treatment of obstructive sleep apnea, a phenomenon called treatment-emergent central sleep apnea, which usually resolves within weeks to months as the body adjusts to therapy. The American Academy of Sleep Medicine guidelines recommend that polysomnography for obstructive sleep apnea should include arousal-based scoring, which helps to more definitively rule out the presence of OSA in patients with symptoms of excessive daytime sleepiness, fatigue, insomnia, or other neurocognitive symptoms 1.
- The guidelines also recommend that an in-laboratory PSG should be performed when the results of an HSAT are negative in a patient with increased risk for OSA, as identification of arousal-based respiratory events is challenging when using most HSAT devices 1.
From the Research
Diagnostic Criteria for Mixed Sleep Apnea
The diagnostic criteria for mixed sleep apnea are not explicitly defined in the provided studies. However, the studies suggest that mixed apneas are a combination of obstructive and central apneas, and their diagnosis is often based on polysomnography (PSG) results.
- Mixed apneas are calculated together with obstructive events in diagnosing obstructive sleep apnea syndrome (SAS) 2
- The apnea-hypopnea index (AHI) is used to diagnose obstructive sleep apnea (OSA), with an AHI of more than five events per hour of sleep considered abnormal 3
- Mixed apneas are associated with respiratory regulation instability and are essential for OSA pathogenesis and prognosis 4
- The clinical significance of mixed apneas needs to be specified, and their relationship with complex SAS and the indices of abnormal respiratory events per standard and revised scoring needs to be evaluated 2
Polysomnography (PSG) in Diagnosing Mixed Sleep Apnea
PSG is a crucial tool in diagnosing mixed sleep apnea, as it measures several sleep variables, including the AHI.
- PSG in an attended setting (sleep laboratory) has been used as a reference standard for the diagnosis of OSA 3
- The AHI measured from portable devices in-home is the sum of apneas and hypopneas per hour of time in bed, rather than of sleep 3
- PSG may also be used for titrating continuous positive airway pressure (CPAP) to individual needs 3
Predictors of Mixed Apneas
Several predictors of mixed apneas have been identified, including: