From the Guidelines
Mixed sleep apnea is defined by the presence of both obstructive and central sleep apnea episodes during sleep, characterized by a combination of physical airway blockage and temporary brain failure to signal breathing, as noted in the 2012 American Academy of Sleep Medicine guidelines 1. The classification of apnea as obstructive, mixed, or central is based on respiratory effort, with mixed apnea involving both obstructive and central components.
- The American Academy of Sleep Medicine task force considered revising the definitions of central and mixed apneas but ultimately recommended no changes to the 2007 scoring manual definitions 1.
- Mixed sleep apnea can occur naturally or emerge during treatment with continuous positive airway pressure (CPAP), and diagnosis requires a sleep study (polysomnography) to distinguish between different types of breathing pauses.
- Treatment approaches for mixed sleep apnea must address both obstructive and central components, and may include CPAP with appropriate pressure settings, adaptive servo-ventilation (ASV), or bilevel positive airway pressure (BiPAP) with a backup rate. The condition is complex, involving destabilization of the respiratory control system in the brain, particularly when obstructive events alter carbon dioxide levels in the blood, triggering changes in breathing drive that can lead to central apneas alongside existing obstructive events, as discussed in the context of respiratory muscle testing and polysomnography 1.
From the Research
Definition of Mixed Sleep Apnea
Mixed sleep apnea is a type of sleep apnea that combines both central and obstructive components 2, 3, 4, 5, 6. It is characterized by a pause in breathing during sleep, followed by a partial awakening, and is often associated with respiratory regulation instability and decreased compliance with continuous positive airway pressure (CPAP) therapy 2.
Key Characteristics
Some key characteristics of mixed sleep apnea include:
- A combination of central and obstructive apneas 3, 6
- Respiratory regulation instability 2
- Decreased compliance with CPAP therapy 2, 3
- Association with treatment-emergent central sleep apnea (TE-CSA) 4
- More frequent occurrence in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS) 5
Predictive Factors
Several factors have been identified as predictive of mixed sleep apnea, including:
- Apnea hypopnea index (AHI) > 47 or lowest oxygen saturation (LSO2) < 77% 2
- Male gender, higher body mass index (BMI), higher scores on Epworth Sleepiness Scales (ESS), and higher triglyceride (TG) levels 5
- Baseline mixed apnea index (MAI) in non-rapid eye movement (NREM) sleep 4
Treatment and Management
Treatment and management of mixed sleep apnea may involve CPAP therapy, although patients with mixed sleep apnea may have poorer adherence to CPAP therapy compared to those with pure obstructive sleep apnea 3. Additionally, low-flow oxygen therapy may alter the frequency and distribution of sleep-induced apnea, increasing the frequency of obstructive apneas while decreasing the frequency of central and mixed apneas 6.