Sleep apnea is a common sleep disorder where breathing repeatedly stops and starts during sleep due to a blocked or collapsed upper airway. Positive Airway Pressure (PAP) therapy is a primary treatment for obstructive sleep apnea (OSA), delivering pressurized air to keep the airway open. This article clarifies the mechanisms and applications of Continuous Positive Airway Pressure (CPAP) and Automatic Positive Airway Pressure (APAP).
What is CPAP?
CPAP stands for Continuous Positive Airway Pressure. This device delivers a single, constant level of air pressure throughout the night. A motor within the machine pressurizes room air and sends it through a hose to a mask worn by the user. This steady stream of air acts as a pneumatic splint, preventing the upper airway from collapsing and allowing for unobstructed breathing.
A healthcare professional determines the pressure setting for a CPAP machine, often following an overnight sleep study. This fixed pressure remains consistent, regardless of changes in sleep position or sleep stage. CPAP is commonly prescribed for individuals with straightforward Obstructive Sleep Apnea where consistent pressure effectively maintains airway patency.
What is APAP?
APAP, or Automatic Positive Airway Pressure, differs from CPAP by offering a dynamic approach to pressure delivery. Instead of a fixed pressure, an APAP machine automatically adjusts the air pressure throughout the night based on the user’s real-time breathing needs. These devices incorporate sensors to continuously monitor breathing patterns.
The sensors detect subtle changes in breathing, such as snoring, flow limitations, or partial airway obstructions. When an event like an apnea or hypopnea is detected, the APAP machine promptly increases the air pressure to clear the airway. Conversely, when breathing is stable and the airway is clear, the machine reduces the pressure to a comfortable minimum. This adaptability makes APAP particularly suitable for individuals whose pressure needs vary throughout the night, perhaps due to changes in sleep position, sleep stage like REM, or other factors.
CPAP Versus APAP
The primary distinction between CPAP and APAP is their pressure delivery. CPAP maintains a single, unchanging pressure level, providing consistent therapy for those with stable airway needs. This fixed pressure approach is often the initial choice for newly diagnosed individuals. CPAP devices are generally less expensive and more widely covered by insurance.
APAP machines offer dynamic pressure adjustments, adapting to the user’s fluctuating respiratory needs throughout the night. This automatic adjustment can lead to enhanced comfort for some users, as the machine delivers only the necessary pressure, potentially resulting in a lower average pressure. APAP’s adaptability can benefit individuals whose sleep apnea severity changes with sleep position, alcohol consumption, or weight fluctuations.
While CPAP’s fixed pressure might feel too high or uncomfortable for some, potentially impacting adherence, APAP’s fluctuating pressure might also cause subtle sleep disruptions for sensitive individuals. APAP devices typically come at a higher cost. Both therapies are effective for most people with obstructive sleep apnea, but APAP may not be suitable for those with complex sleep apnea or certain other respiratory conditions where a consistent, precisely titrated pressure may be more appropriate.
How PAP Therapy is Prescribed
Determining the appropriate PAP therapy, whether CPAP or APAP, is a medical decision guided by a healthcare professional. The process begins with a comprehensive sleep study, known as polysomnography, which diagnoses sleep apnea and determines its severity. This study monitors physiological parameters during sleep, including breathing patterns, oxygen levels, and brain activity.
During a sleep study, a technician may also conduct a PAP titration, testing different pressure settings to identify the optimal level needed to keep the airway open. Based on the sleep study results, a sleep specialist or doctor interprets the data and prescribes the specific type of PAP machine and the appropriate pressure range. Follow-up appointments monitor the therapy’s effectiveness and make necessary adjustments to pressure settings or mask fit, ensuring continued comfort and efficacy.