Hypopnea is a sleep-related breathing disorder characterized by a partial blockage or reduction in airflow during sleep. Breathing airflow drops by at least 30% for 10 seconds or longer. This reduction can lead to a decrease in blood oxygen levels or cause a brief awakening from sleep.
Hypopnea Symptoms and Causes
Common symptoms of hypopnea include excessive daytime sleepiness and loud, frequent snoring, often interrupted by gasping or choking sounds. Individuals may also wake up with morning headaches, experience difficulty concentrating, irritability, depression, lack of energy, and impaired memory due to fragmented sleep.
Hypopnea is caused by physical obstructions or central nervous system issues. Obstructive hypopnea, the most frequent type, occurs when throat muscles and tissues relax excessively during sleep, partially blocking the airway. This can be due to the anatomy of the jaw, tongue, or enlarged tonsils and adenoids. Central hypopnea arises when the brain fails to send proper signals to breathing muscles, leading to reduced breathing effort.
Risk factors for hypopnea include obesity, as excess neck weight can narrow the airway. Age is also a factor, with hypopnea more common in middle-aged and older men. Lifestyle choices like alcohol consumption before bed and the use of sedatives or sleeping pills can relax throat muscles. A family history of sleep-disordered breathing, hypothyroidism, or certain heart and kidney diseases may also increase risk.
Distinguishing Hypopnea from Apnea
Hypopnea and apnea are both forms of sleep-disordered breathing, differing in airflow reduction. Hypopnea involves a partial decrease in airflow (at least 30% for 10 seconds or more). In contrast, apnea is characterized by a complete cessation of breathing for at least 10 seconds, where airflow stops entirely.
Both types of events are quantified by the Apnea-Hypopnea Index (AHI). The AHI is a standard diagnostic metric representing the total number of apnea and hypopnea events per hour of sleep. It is calculated by summing the number of apneas and hypopneas, then dividing by total sleep hours.
The AHI severity scale for adults is categorized as follows:
- Fewer than 5 events per hour is normal.
- 5 to 14 events per hour indicates mild sleep apnea.
- 15 to 29 events per hour suggests moderate sleep apnea.
- 30 or more events per hour signifies severe sleep apnea.
The Diagnostic Process
Diagnosing hypopnea relies on a medical evaluation and a sleep study. Polysomnography (PSG) is the most comprehensive diagnostic tool. This test is conducted in a sleep laboratory, monitoring a person’s sleep throughout the night. Sensors attached to the body record various physiological parameters.
These sensors track brain waves for sleep stages, heart rate, blood oxygen levels, and breathing patterns, including airflow and respiratory effort. Leg movements and body position are also monitored. PSG data allows professionals to identify and quantify hypopnea and apnea episodes, leading to an AHI score.
A home sleep apnea test (HSAT) may be a convenient alternative to an in-lab study. HSATs involve fewer sensors and monitor a more limited set of parameters, such as breathing patterns and blood oxygen levels. They may not be as comprehensive as a full polysomnography.
Available Treatment Options
Continuous Positive Airway Pressure (CPAP) therapy is an effective treatment, particularly for moderate to severe cases. A CPAP machine delivers a continuous stream of pressurized air through a mask worn over the nose or mouth during sleep. This constant airflow acts as a pneumatic splint, keeping the upper airway open and preventing tissue collapse.
Lifestyle modifications can help manage hypopnea. Losing weight can reduce fat deposits around the neck that contribute to airway narrowing. Avoiding alcohol and sedatives before bedtime is advised, as these substances can relax throat muscles. Changing sleep positions, such as sleeping on one’s side, can help keep the airway open.
Oral appliance therapy is another treatment, particularly for mild to moderate cases. These custom-fit mouthguards, called mandibular advancement devices (MADs), are worn during sleep. They reposition the lower jaw forward, keeping the airway clear and preventing tongue and soft tissue collapse.
Surgical procedures may be considered if other treatments are ineffective or not tolerated. These surgeries correct anatomical issues obstructing the airway. Procedures include removing enlarged tonsils or adenoids, or modifying soft tissues in the palate or tongue. More advanced surgeries might involve repositioning the jaw or stimulating nerves that control tongue movement.