Distinguishing Between Obstructive, Central, and Mixed Apnea Patterns During Home Sleep Study Data Review
A critical task for the sleep specialist reviewing a Home Sleep Apnea Test is to categorize the type of respiratory events recorded.
Obstructive Sleep Apnea (OSA) is the most common and is identified on the HSAT by a cessation of airflow in the nasal cannula while the RIP belts continue to show rhythmic movement of the chest and abdomen. This indicates that the "bellows" of the body are working, but the "pipe" (the throat) is shut.
Central Sleep Apnea (CSA) presents a different pattern. In this case, both the airflow and the movement of the chest/abdomen stop simultaneously. This indicates that the brain has temporarily failed to signal the diaphragm to move. While some central events are normal during sleep transitions, a high frequency of them may point toward underlying neurological or cardiac issues.
Finally, there are Mixed Apnea events. These usually begin as a central event (no effort and no flow) and end as an obstructive event (effort resumes but flow is still blocked). A Home Sleep Apnea Test that shows a high percentage of central or mixed events often requires a follow-up in-laboratory study. This is because the treatment for central apnea—such as Bilevel Positive Airway Pressure (BiPAP) with a back-up rate—is more complex than the standard CPAP used for simple obstructive apnea and requires precise titration that can only be performed by a technician in a lab.