Central sleep apnea syndrome or Central Sleep Apnea (CSA) is a disorder where a patient’s breathing repeatedly stops while he is asleep. This happens when brain temporarily ceases to send signals to the respiratory system. A CSA episode usually lasts anywhere from 10 seconds to 30 seconds. These events are either cyclic or intermittent and are typically associated with decreased levels of oxygen in the blood.
Though not as common as obstructive sleep apnea (OSA), central sleep apnea is still considered as a life-threatening condition. Just as in OSA, in a central sleep apneic episode, there is an inadequate supply of oxygen going into the body as well as the brain, which in turn, increases the level of CO2 in the body. This can result in the development of several life-threatening conditions.
Causes of Central Sleep Apnea
There are many reasons for the development of Central Sleep Apnea, some of which include:
Being obese or overweight is linked to central sleep apnea. Increased blood pressure and inflammation tend to accompany an obese/overweight person. These medical conditions can impact the brain and can also affect the nervous system, triggering a central sleep apneic episode.
Excessive use of opioids and narcotics can also result in triggering a CSA episode. Though these medicines efficiently act against pain by numbing nerves in the affected area, it can even have an impact on the brain. If the nerves in the brain become numb or get paralyzed, then it impacts the signaling process to the nervous and respiratory system that breathing has to be restarted. If a person has been prescribed a narcotic or opioid and has also been diagnosed with sleep apnea, then this should be brought to the attention of the doctor since it can turn life-threatening.
Ailments of Brain Stem
Diseases of lower brainstem have also been cited as one of the primary reasons for a person developing central sleep apnea. People who suffer from brain infections, brain diseases, trauma and spinal issues are at higher risk for having central sleep apnea. Since lower brainstem controls breathing, any impact on the brainstem can result in the brain not sending the proper signal to the body to restart breathing.
Some other issues that can trigger an episode of central sleep apnea include congestive heart failure, male gender, age above 40 years, kidney failures, hypothyroidism, as well as neurological issues.
Besides the type of central sleep apnea that occurs due to the causes mentioned above, there is another type of central sleep apnea that is known to develop without any specific reason and does not have an association with any other disease.
Symptoms and Treatments for Central Sleep Apnea
Though there are many symptoms of central sleep apnea, some common ones include:
Once a person is diagnosed with sleep apnea, the physician can offer various treatment options to the patient, which usually involves CPAP therapy for patients with obstructive sleep apnea. CPAP device blows air at one constant pressure setting throughout the sleep cycle.
- Frequent awakening during the night
- Fatigue and tiredness during daytime
- Frequent visits to the bathroom during night
- Early morning headaches
- Mood swings
- Memory and concentration issues
However, for a patient with central sleep apnea, this type of treatment is ineffective. They require two pressure settings – one setting for inhaling and one for exhaling. The devices used for providing these specific settings are called Bilevel Positive Airway Pressure or BiPAP devices. However, BiPAP has been found to trigger CSA in patients who have obstructive sleep apnea.
To specifically treat central sleep apnea, scientists have developed Adaptive Servo-Ventilation (ASV) device, and the therapy is known as Adaptive Servo-Ventilation therapy.
Adaptive Servo-Ventilation or ASV Therapy
Though it is a relatively uncommon sleep apnea disorder, patients having CSA have some good options. APAP, CPAP and BiPAP devices treat sleep apnea by blowing air at one constant pressure setting. Adaptive Servo-Ventilation (ASV) therapy, a relatively nascent therapy, on the other hand, is a non-invasive, user-friendly therapy which utilizes ASV devices to continually change pressure flow settings based on the actual breathing pattern of the CSA patient. A key point which differentiates ASV therapy from other therapies is the fact that ASV supports regular breathing.
ASV uses ‘smart’ technology (an algorithm) for sensing the patient’s breathing pattern (pauses or reductions) and makes continuous adjustments in the air pressure to ensure the patient's breathing is stable at 90% of his earlier regular breathing pattern.
ASV algorithm is based upon a standard rate of BPM (Breaths Per Minute) that a person should ideally be taking. When the breathing rate falls below a predetermined level, then ASV devices helps in delivering air pressure that is required to ensure that the breathing pattern becomes normal again.
Besides this, ASV device also provides backup support for the person’s steady breathing to ensure the airways remain open to prevent any obstructions. The ASV device typically provides 50% reduction in efforts for maintaining a natural breathing pattern. Since ASV technology is still nascent stages, studies are being undertaken to increase the efficacy of the technology.
Word of Caution
As part of ongoing studies, researchers in May 2015 found that chronic heart failure and adaptive servo-ventilation had an alarming correlation, and use of ASV was known to increase heart failure. Though it is still unclear how ASV increases heart failure, doctors are erring on the side of caution and are recommending not to use ASV therapy in patients who have a neuromuscular disease, severe lung disease, or chronic hypoventilation.