Sleep Apnea
Sleep apnea is a disorder that is caused by the collapse of the airway while patients sleep. When the patient is awake, portions of the airway, including the soft palate, are held up by muscle tension. These muscles relax during sleep, causing the soft palate to droop. Patients with sleep apnea often have an abnormally narrow airway, so that when the soft palate drops down, the airway is obstructed. This causes the patient to wake up slightly, which prevents a full night of sleep. CPAP (continuous positive airway pressure) machines, designed to be worn while the user is sleeping, work to help keep the airways open, allowing the patient to sleep throughout the night.
Components of a CPAP Machine
There are three main parts to CPAP machines. The first part is the mask portion of the machine. This part either fits over the user's nose and mouth or the nose alone. This device is held in place by straps that go around the user's head. The second part is the motor of the machine, which is used to pump air. The motor is connected to the mask via a tube which allows airflow. The motor of the machine is used as an air compressor, which then causes air to be pushed through the tube and into the mask. Because the motor runs continuously while the machine is turned on, there is a constant flow of air into the mask.
CPAP Mechanism
During normal breathing, there is a naturally occurring period of time (between inhalation and exhalation) when there is no airflow through the windpipe (bronchus). It is during this period of time that the soft palate (which is made up of some of the tissue in the upper part of the mouth's posterior as well as some of the throat) is able to droop. This is especially problematic during deep sleep when, due to decreased oxygen use, there are longer pauses between breaths, leading to collapse of the airway. CPAP machines keep the airway open by ensuring that there is always air flowing through the respiratory system. CPAP machines contain pressure sensors to ensure that the machine does not pump too much air, as this could make exhalation difficult. The CPAP device is typically controlled by a simple computer program which monitors air flow and makes adjustments to the motor's speed to keep the air flow in a narrow range. The air flow can be sped up or slowed down by changing the machine's settings, although this generally involves accessing "clinician mode," which is designed only to be used by physicians or technicians. These settings can only be accessed by pressing a specific combination of buttons. The exact sequence varies depending on the machine and the manufacturer.
