The most common finding in the sleep study are breathing problems. As mentioned earlier, these events are not normally recognized by the patient but by family and friends. We normally look for apneas and hypopneas in the airflow channel. Apneas are a complete cessation of airflow in the airflow channel and hypopneas are reduced breathing in the airflow channel. Apneas and hypopneas last longer than 10 seconds and are usually caused by the same thing. Hypopneas are not as severe because the patient is still moving some air.
There are three types of apneas and two types of hypopneas, and we look at the effort channel to see what types of either are present as the different types are treated differently.
The first type of apnea and hypopnea are obstructive events. These events are caused by either excessive tissue in the airway or by relaxation of the muscles that normally hold the airway open. The second type of apnea and hypopnea are central events: these are usually associated with altitude, electrolyte imbalances, congestive heart failure and/or brain stem lesions. The final type of apnea called mixed apnea is a combination of both obstructive and central apnea. All breathing events may lead to heart rate variations, drops in oxygen, arousals and or awakenings.