Continuous Positive Airway Pressure (CPAP) therapy is a common treatment for obstructive sleep apnea, a condition where breathing repeatedly stops and starts during sleep. CPAP machines deliver a steady stream of pressurized air to keep the airway open, aiming to improve sleep quality and overall health. To gauge therapy effectiveness, CPAP machines collect and display various data points, with “Events Per Hour” being a significant metric. This article explains what “Events Per Hour,” also known as the Apnea-Hypopnea Index (AHI), signifies on a CPAP machine.
Understanding Events Per Hour
Events Per Hour (EPH), also known as the Apnea-Hypopnea Index (AHI), measures the average number of breathing disruptions experienced during each hour of sleep while using a CPAP machine. This metric combines different types of respiratory events.
The three primary types of events included in this calculation are apneas, hypopneas, and sometimes respiratory effort-related arousals (RERAs). An apnea occurs when airflow to the lungs completely stops for at least 10 seconds. Hypopneas involve a partial blockage of the airway, resulting in a significant reduction in airflow for at least 10 seconds. RERAs are brief awakenings from sleep caused by increased breathing effort. The AHI is calculated by dividing the total number of apneas and hypopneas (and sometimes RERAs) by the total hours of sleep.
Interpreting Your EPH Score
An ideal AHI score for effective CPAP therapy is fewer than five events per hour. Some sleep specialists even aim for one or two events per hour as a “safe zone,” reflecting minimal breathing disruptions.
An EPH value consistently above five suggests that sleep apnea may not be adequately controlled by current CPAP settings or therapy. For instance, an AHI between 5 and 14 events per hour is typically classified as mild sleep apnea, 15 to 29 as moderate, and 30 or more as severe.
CPAP machines provide an estimate of your AHI, and this measurement should always be interpreted by a healthcare professional or sleep specialist. They consider your individual health, initial sleep study results, and ongoing symptoms to properly assess the meaning of your EPH score. Relying solely on the machine’s reported number without professional guidance might lead to misinterpretations or inappropriate self-adjustments.
Factors Influencing EPH and Next Steps
Several factors can influence a CPAP user’s “Events Per Hour” (EPH) score, potentially causing it to be higher than desired. A common reason is an improper mask fit or leaks, which can prevent the machine from delivering the prescribed air pressure effectively. Air escaping from the mask reduces the positive airway pressure, allowing breathing events to occur.
Sleeping position can also play a role; for some individuals, sleeping on their back may worsen sleep apnea symptoms and increase the AHI. Machine settings, particularly the pressure level, might need adjustment if the current setting is not sufficient to keep the airway open.
Lifestyle factors, such as recent weight gain, alcohol consumption, or the use of certain medications, can also impact breathing patterns during sleep and elevate the EPH score. In some cases, a consistently high AHI could signal underlying health issues or even the development of central sleep apnea, where the brain fails to send proper signals to the breathing muscles.
If your EPH remains consistently high, or if you experience persistent symptoms like daytime sleepiness despite using your CPAP machine, it is advisable to consult your sleep doctor or CPAP provider. Before seeking professional help, you can regularly check your mask for proper fit and seal to minimize leaks. Reviewing sleep habits, such as avoiding alcohol before bed, may also be beneficial.
It is important not to self-adjust machine settings, as this could lead to ineffective therapy or even worsen the condition. Your healthcare provider can evaluate your data, make necessary adjustments to your therapy, or recommend further diagnostic steps to ensure your treatment is optimized.