Sleep apnea is a type of sleep disorder that occurs when a person experience pauses in breathing during sleep. In cases of untreated sleep apnea, people experience a complete halt in breathing for several seconds, repeatedly during sleep. This can be potentially dangerous and sleep apnea is considered a serious disorder.
Sleep apnea can affect people of all ages, but it is most common with people over the age of 40 and people who are overweight. This condition also occurs in approximately 25% of men and 10% of women. There are, of course, certain risk factors for sleep apnea, which increase one’s chance of developing the condition. Luckily, sleep apnea can be treated with CPAP, BiPAP, or APAP machine therapy, mouthpieces, medicaments, or surgery.
In the following paragraphs, we’re going to take a look at the types of sleep apnea that people can develop. We’ll see what the similarities and differences between these types are and how they’re treated. So, without further ado, let’s get started!
Sleep Apnea Classification
There are two types of sleep apnea; apnea, also known as obstructive apnea, and central apnea, also known as a hypopnea. Let’s look at them in more detail;
Obstructive Sleep Apnea
Obstructive sleep apnea or OSA is the most common type of sleep apnea. It is known for its characteristic, repetitive episodes of complete or partial obstruction of the upper airway during sleep. OSA episodes can last for several seconds but can occur even a hundred times throughout the night.
That is why OSA is known to seriously interfere with sleep and overall health. It can reduce the flow of oxygen to the vital organs or cause serious heart rhythm irregularities.
For that reason, OSA usually occurs together with cardiovascular disease or is prevalent in patients with cardiovascular disease. Most people suffering from OSA also experience frequent and loud snoring.
Sometimes the airflow is reduced or blocked, so the snoring is not as loud. There can be even occurrences of choking, snorting or gasping when the airway unblocks and reopens. Here are some other details essential to obstructive sleep apnea;
- Measurement – Obstructive sleep apnea is measured via the apnea-hypopnea index or AHI. The index represents an average number of how many times apneas and hypopneas occur in an hour of sleep.
- Prevalence – OSA can occur in the age group, but it occurs more in middle and older age. Approximately 24% of men and 9% of women develop OSA symptoms in their lifetime, and approximately 85% of adults with OSA remain undiagnosed and are not treated.
- Types – According to the apnea-hypopnea index, there are three types of OSA; mild OSA (AHI of 5 to 15), moderate OSA (AHI of 15 to 30), and severe OSA (AHI of more than 30).
- Risk groups – OSA is most likely to occur in overweight people (Body Mass Index of 25 to 29.9), and obese people (Body Mass Index of 30 and above). It is also likely to occur in menopausal women, middle-aged and older men, ethnic minorities, people with soft tissue structure abnormalities, people with family members who have OSA, people who suffer from nocturnal nasal congestion and rhinitis.
- Effects – OSA usually causes increased heart rate, increased risk of stroke, a higher rate of death due to heart disease, impaired glucose tolerance, mood changes, impaired concentration, sleep deprivation, etc.
- Treatment options -Upon OSA diagnosis, patients can be treated using CPAP machines (continuous positive airways pressure machines), oral appliances, surgery, behavioral changes (weight loss), positional therapy, and over-the-counter remedies to reduce snoring.
Note: Complex sleep apnea is also known as mixed sleep apnea; patients tend to have symptoms of both OSA and CSA, but in the medical community, complex sleep apnea is considered to be a type of CSA because it is treatment-emergent (treatment by CPAP for OSA), and due to current lack of research on this topic.
Central Sleep Apnea
Central sleep apnea is characterized by pauses in breathing during sleep, known as apneas. These pauses, unlike in OSA, don’t occur because the airway is blocked; they occur because there is a pause in breathing efforts.
This means that the brain has a slow response to the change in oxygen levels and carbon dioxide levels. The breathing reflex becomes blunt, and normal breathing becomes impaired.
CSA can also occur due to slow circulation from heart failure, where there are cases of under-breathing, over-breathing, and stopping breathing.
There have been cases of CSA occurring because of weak lung muscles or neuromuscular disorders like polio. Overall, central sleep apnea is known to interfere with normal sleep and causes the body to retain carbon dioxide.
This can usually lead to complications like morning headaches, dizziness, and confusion. Here are some other details essential for central sleep apnea;
- Measurement – Central sleep apnea is measured via the apnea-hypopnea index or AHI, just like OSA. The index represents an average number of how many times apneas and hypopneas occur in an hour of sleep. A single central apnea event usually lasts around 10 seconds.
- Prevalence – The prevalence of CSA is quite low; less than 1% in both men and women. Approximately 25% of patients with heart failure have central sleep apnea, and 10% of patients who have had a stroke also had CSA.
- Types – there are several types of CSA; Cheyne-Stokes Breathing, complex apnea, sleep transition apnea, narcotic-induced central apnea, idiopathic central sleep apnea, and medical-condition-induced central sleep apnea.
- Risk groups – CSA is more likely to occur in men than in women and it also occurs more in older adults, especially people over 65 years of age. It is also more likely to occur in people with cardiovascular disorders, stroke or brain tumor patients, people who use opioid medications, or people who use CPAP machines to treat obstructive sleep apnea.
- Effects – CSA usually causes abrupt awakenings during the night, shortness of breath, sleep deprivation and insomnia, excessive daytime sleepiness, mood changes, chest pain during the night, morning headaches and confusion, snoring, and lack of physical strength.
- Treatment options – CSA is often treated via CPAP machines, adaptive-servo ventilation or ASV, BiPAP machines, reduction of opioid medication, supplemental oxygen, medication, surgery, and other procedure slike nerve stimulation.
Types Of Obstructive Sleep Apnea
As briefly mentioned previously, there are three types of obstructive sleep apnea;
- Mild OSA (AHI of 5 to 15) – Mild obstructive sleep apnea is characterized by sleep interruptions that occur 5 to 15 times per hour, during the night. The symptoms of mild OSA include unwanted sleepiness, involuntary sleeping episodes, issues with the attention span, etc. Involuntary sleepiness usually occurs during activities that require little focus, like reading or watching TV. Many argue that mild OSA shouldn’t be specifically treated, but there should be more studies coming from the American Thoracic Society regarding the value of mild OSA treatment.
- Moderate OSA (AHI of 15 to 30) – Moderate obstructive sleep apnea is characterized by sleep interruptions that occur between 15 and 30 times per hour, during the night. Common moderate OSA symptoms include snoring, depression and mood swings, low attention and concentration span, restless sleep, excessive sleepiness during the day, lack of energy, nighttime choking, coughing or gasping, weight gain, etc.
The symptoms of moderate OSA seem very similar to those of mild OSA. However, the difference is that these symptoms are more pronounced in moderate OSA, and tend to require thorough observation and treatment. The treatment options usually include weight loss, alcohol reduction, change in sleep habits, quitting tobacco, and other lifestyle changes.
- Severe OSA (AHI of more than 30) – Severe obstructive sleep apnea is characterized by sleep interruptions that occur more than 30 times per hour, during the night. Studies show that severe OSA increases the death risk in overweight people, people who are smokers, who are of middle- and older age, etc. The symptoms of severe OSA include excessive daytime sleepiness, serious episodes of stopped breathing during sleep, loud snorings, gasping and choking alongside abrupt awakening, dry mouth and sore throat upon awakening, concentration difficulties, etc. Treatment options for severe OSA include CPAP treatment, oral appliance, medication, surgery, and thorough lifestyle changes.
We also have to mention the Respiratory Effort Related Arousal (RERA). This refers to the limitation in breathing that results in increased respiratory effort. This effort often culminates in arousal, however, it doesn’t meet the criteria from apnea or hypopnea.
Types Of Central Sleep Apnea
There are several types of CSA, depending on the cause. The types include;
- Cheyne-Stokes Breathing – this type of central sleep apnea is caused by cardiovascular issues, congestive heart failure, or stroke. It is usually characterized by oscillations in breathing effort and airflow. The lowest breathing effort usually results in a complete cessation of airflow. Studies have shown that CPAP therapy can help with the oxygen tension, breathing effort, and breathing pattern in this type of central sleep apnea.
- Complex apnea – previously known as ‘treatment-emergent central apnea’, complex apnea usually occurs in patients that were previously exposed to CPAP treatment. This phenomenon occurs in 10% of CPAP treatments. Patients tend to develop central sleep apnea during the treatment, where the respiratory events persist despite the therapy. However, studies about this type of apnea are scarce, so it is hard to determine treatment for ‘treatment-emergent’ or complex sleep apnea.
- Sleep transition apnea – this type of central sleep apnea refers to breathing oscillations and changes that occur while an individual is in the process of falling asleep. In the medical community, sleep transition apnea is described as involving arousal from sleep, which is directly associated with disturbances in breathing. The treatment is often determined in accordance with the underlying issues that lead to sleep transition apnea.
- Narcotic-induced central sleep apnea – this type of central sleep apnea appears in people who undergo a narcotic therapy, either due to chronic pain or drug abuse. Between 10% and 50% of chronic narcotic therapy, patients develop central sleep apnea. Patients develop respiratory difficulties due to narcotic dosing. However, more data is currently lacking when it comes to lower doses and the development of central apnea.
- Idiopathic central sleep apnea – this is a rather uncommon type of central sleep apnea. It is characterized by periodic episodes of apnea resulting from decreased neural input to the respiratory motor neurons. Patients suffering from this type of apnea usually experience restless sleep, snoring, insomnia, and excessive daytime sleepiness.
- Medical condition-induced central sleep apnea – medical conditions like heart failure, stroke, Parkinson’s disease, and kidney failure usually cause central sleep apnea.
Sleep apnea is a condition that is well researched, but surely needs more studying. The two main types of apnea may require a more thorough observation in the future so that we become a better understanding of the symptoms, their similarities, and differences as well as treatment options.
However, for now, this is what we know; the existing types of sleep apnea serve as a good way to find proper, specialized treatment for each type. We hope that the presented information has been insightful. For more information about sleep apnea and each type, make sure to discuss with your doctor or a medical professional.