Continuous Positive Airway Pressure (CPAP) therapy is a medical treatment for sleep-related breathing disorders, most notably sleep apnea. The CPAP machine delivers a constant stream of pressurized air through a mask worn during sleep. This pressurized air acts as a pneumatic splint, keeping the upper airway open and unobstructed. This prevents breathing pauses, ensuring a steady supply of oxygen and stabilizing nighttime breathing. CPAP therapy significantly improves sleep quality and reduces strain on the cardiovascular system.
Recognizing the Warning Signs
The initial indicators suggesting a person may need a CPAP machine often stem from subjective experiences and observations made by a bed partner. Loud, persistent snoring is one of the most common signs, particularly when it is disruptive or punctuated by periods of silence. This silence is often followed by a choking or gasping sound as the person struggles to resume breathing, an event known as an apnea or hypopnea.
A person may wake up suddenly feeling a choking sensation or with a dry mouth and sore throat. These nighttime events cause frequent, brief awakenings that fragment sleep, often without the person realizing it. This leads to the most pervasive daytime symptom: chronic daytime fatigue or excessive somnolence, where a person feels deeply exhausted even after a full night in bed.
This exhaustion, sometimes called hypersomnia, can manifest as difficulty concentrating, irritability, and memory problems. Waking up with a headache is also a frequent complaint, likely due to changes in carbon dioxide and oxygen levels during nighttime breathing interruptions. If a bed partner reports observed pauses in breathing, or if the individual experiences these chronic daytime effects, a formal medical evaluation is needed.
Diagnostic Criteria for CPAP Eligibility
Determining the need for CPAP therapy involves transitioning from recognizing subjective symptoms to obtaining objective, measurable data through a sleep study. The standard diagnostic tool is a polysomnography, which monitors various physiological parameters during sleep, including brain activity, heart rate, oxygen levels, and breathing patterns. The primary metric derived from this study is the Apnea-Hypopnea Index (AHI).
The AHI represents the average number of apneas (complete cessation of airflow for at least ten seconds) and hypopneas (a partial reduction in airflow of at least 30% for ten seconds, accompanied by a drop in blood oxygen levels) that occur per hour of sleep. This number classifies the severity of sleep-disordered breathing.
The severity of sleep apnea is classified based on the AHI:
- Fewer than five events per hour is considered normal, indicating healthy breathing.
- Mild sleep apnea ranges from 5 to fewer than 15 events per hour.
- Moderate sleep apnea is defined by 15 to fewer than 30 events per hour.
- Severe sleep apnea signifies 30 or more events per hour.
CPAP is typically mandated for individuals diagnosed with moderate or severe sleep apnea. It may also be prescribed for people with mild sleep apnea who experience significant daytime sleepiness or have related health conditions, such as hypertension or cardiovascular disease. The goal of CPAP treatment is to reduce the AHI to below five events per hour.
Specific Medical Conditions Requiring CPAP Therapy
The underlying cause of the breathing interruptions determines the specific type of sleep apnea diagnosed, which in turn informs the most appropriate positive airway pressure (PAP) therapy. The vast majority of cases are classified as Obstructive Sleep Apnea (OSA), which occurs when the soft tissues in the throat relax during sleep, physically blocking the upper airway. CPAP is the primary treatment for OSA, as the constant air pressure prevents this physical collapse of the tissue.
A less common condition is Central Sleep Apnea (CSA), which is caused by a communication problem where the brain temporarily fails to send the necessary signals to the muscles that control breathing. Unlike OSA, there is no physical blockage of the airway in CSA, and the treatment approach may differ. While CPAP can sometimes be used to stabilize breathing in CSA, the condition often responds better to other forms of positive airway pressure, such as BiPAP (Bilevel Positive Airway Pressure) or Adaptive Servo-Ventilation (ASV).
A third category, Complex or Mixed Sleep Apnea, involves features of both OSA and CSA. In all these cases, machine-assisted breathing is necessary to ensure consistent oxygenation and prevent the serious health complications associated with untreated sleep-disordered breathing. The medical diagnosis dictates the specific type of machine needed.