Therapies that mechanically open the upper airway
Continuous positive airway pressure (CPAP) therapy
CPAP therapy is the most common treatment for OSA. CPAP therapy involves increasing the positive air pressure in the upper airway to prevent the airway from collapsing from negative pressure created when breathing in during sleep. The CPAP machine consists of the motor, hose and mask. The CPAP motor pressurizes and in some cases adds moisture to the air. The pressurized air is then sent through the hose to the mask.
Prior to using the CPAP machine, users undergo a titration study to determine the ideal air pressure for sleep. During the study, the user is fitted for a mask. While the user is sleeping, the clinicians slowly increase the pressure of the air released into the mask until the patient no longer wakes up while sleeping. There are three types of masks: nasal pillows, nasal masks and full face masks. Effects are experienced almost immediately.
Treatment often reduces snoring and breathing obstructions, improves sleep quality, reduces risk for cardiovascular diseases, lowers blood pressure, increases alertness during the day and reduces daytime drowsiness. One disadvantage of CPAP is that while it initially gradually increases to the optimal pressure level at the beginning of sleep, it stays at that optimal pressure setting, regardless of how the individual’s pressure changes with changes in sleep position, body size or sleep state. Since all these factors can affect comfort during sleep, this can be an issue. Another complaint of CPAP users is that the single level of pressure can be difficult to exhale against. However, to relieve the pressure during exhalation. CPAP can be used with C-flex which adjusts pressure as needed.
Automatic PAP (APAP)
CPAP is not the only positive airway pressure device. Two similar devices include the automatic or auto-titrating PAP (APAP) and the bilevel PAP (BiPAP or BPAP). The APAP is similar to CPAP in that they deliver pressurized air during sleep to prevent upper airway collapse. The difference is APAP can switch between two different pressurized air settings in response to changes in the user’s breathing.
There are situations in which the body is more and less likely to experience a respiratory event. For example, individuals are more likely to experience a respiratory event when the user is sleeping on his or her back or in REM sleep (when the muscles are more relaxed). Most can also be set at CPAP mode and eject only one level of pressurized air as well. Since receiving high pressure air when not needed can cause discomfort, APAP may provide more restful sleep. However, most sleep comfortably under CPAP conditions alone.
Bilevel PAP (BPAP)
The BPAP also provides positive airway pressure through a mask like the CPAP and APAP. It differs from CPAP in that it can be set in a breath timing phase. This phase measures how often a breath should be taken.
If there is a delay between breaths, the machine increases air pressure to allow the person to breath. These machines are best for people that have not had success with the CPAP machine, have high pressure settings or low oxygen levels, or have cardiopulmonary, lung or neuromuscular disorders. BPAP differs from CPAPs with C-flex in that it can lower positive pressure considerably more than C-Flex. The level of pressure relief provided by BPAP also varies with each breath, while C-Flex only drops one level.
Nasal expiratory PAP (EPAP) devices
EPAP devices are small, nasal devices with valves that open during inhalation and partially close during exhalation. These devices are placed in the nostrils and have an adhesive seal to keep them in place during sleep.
The high expiratory resistance generates positive pressure while the user is breathing out, which causes the upper airway to open and resist collapse while breathing in. treatment has been shown to reduce AHI when used. The benefits of this treatment is that it is immediate, portable and is associated with greater patient compliance than with CPAP related devices. This device only delivers positive pressure when breathing out.
Oral appliances (OAs) therapies
Oral appliances or OAs are another treatment option for OSA. OAs are devices worn during sleep that are custom made for the user’s mouth. It functions by positioning the jaw in a forward position to maintain an open upper airway. The advantages of these devices include that they are comfortable, easy to use, quiet, portable and easy to maintain. Two commonly used devices include: mandibular advancement devices (MADs) and tongue-retaining devices (TRDs). OAs can be used in combination with CPAP to improve OSA symptoms.
Mandibular advancement devices (MADs)
Mandibular advancement devices or MADs are the most common dental sleep device. They open up the airway by moving the lower jaw (mandible) forward during sleep. By moving the jaw forward, the portion of the airway vulnerable to collapse is held open by moving many airway muscles, such as the tongue, forward. In addition to repositioning the muscles, the devices increases the activity of these muscles, resulting in overall stronger airway muscles.
Tongue-retaining devices (TRDs)
Another commonly used OA is the tongue-retaining device or TRD. TRDs fit over the tongue and work by placing and keeping the tongue in a forward position during sleep. This treatment is best for those with mild or moderate OSA, those with a large tongue or a tongue that becomes too relaxed during sleep, those with large tonsils or long uvulas and those with hypothyroidism. Disadvantages of TRDs include excessive salivation (specifically during the first week of use), and difficulty swallowing.
Surgical Therapies
Maxillomandibular advancement
For severe cases of OSA, surgery may be needed. The main type of treatment for OSA is maxillomandibular advancement or MMA. MMA is also known as orthognathic surgery, bimaxillary advancement (Bi-Max), or maxillomandibular osteotomy (MMO). The surgery involves moving the upper jaw (the maxilla) and the lower jaw forward. The procedure is often done in combination with Genial tubercle advancement (tongue advancement). While very successful, because of the treatment is invasive and has a long recovery time, this surgical procedure is typically only prescribed when other forms of OSA treatment are unsuccessful, including other forms of surgery (such as nasal surgery, tonsillectomy, uvulopalatopharyngoplasty and tongue reduction surgery).
Genial tubercle advancement (GTA)
Another surgical option is genial tubercle advancement or GTA. Also known as genioglossus advancement, GTA involves moving the base of the tongue forward to increase the size of the upper airway. As mentioned above, it is commonly performed in conjunction with MMA or uvulopalatopharyngoplasy.
Positional therapy
Positional therapy treats OSA by encouraging the sleeper to sleep in a position less likely to restrict the airway. Many people with OSA only experience it in specific sleeping positions, specifically when sleeping in the supine position (on his or her back). OSA is not experienced when sleeping on their side. Positional therapy can take a variety of forms. One common method is a positional therapy device that is worn around the waist or back that keeps the individual sleeping on their side. There are also small devices that can be worn on the back of the neck that can detect when the sleeper is on his or her back. When the supine position is detected, the device provides a small vibration that does not wake the sleeper, but causes them to change positions. These therapies are typically effective alone or with other sleep apnea treatments.
Lifestyle changes
There is evidence that changes in lifestyle, specifically changes that increase weight loss, like diet and exercise, in overweight individuals can reduce OSA symptoms. While physical exercise alone does not have a major impact on OSA, exercise in combination with diet significantly reduces AHI. Exercise itself may not have a major effect on OSA, but it does promote weight maintenance which is a key factor in preventing and reducing the risk for OSA.
Activation of upper airway muscles
Stimulation of the hypoglossal nerve
For OSA that appears to be due to impaired upper airway muscle function, one viable treatment solution is muscle nerve stimulation. This is done by surgically implanting a stimulation device linked to a cuff or electrodes that are placed around the targeted nerve. Non-invasive methods of stimulation such as transcutaneous methods have also been studied. Stimulation has been shown to improve multiple factors including:
- Inspiratory airflow
- AHI
- Apnea duration
- Oxygen saturation
- Arousal index
- Sleep architecture
- Excessive daytime sleepiness
Some clinical studies have shown that improved AHI lasts for an extended period of time in up to 66% of treated patients. However, determining who will respond to the treatment remains a hurdle.
Pharmaceuticals
Few pharmacological therapies have been shown to be effective against OSA. One exception is desipramine. Desipramine is an antidepressant that functions as a noradrenergic, a mild serotonergic and a mild antimuscarinic. Treatment with this therapeutic has been shown to improve airway collapsibility and OSA severity for those with low muscle responsiveness. Zolpidem, a drug used to treat insomnia, has also been shown to improve pharyngeal muscle responsiveness in cases where the airway is reduced.
Designer Receptors Exclusively Activated by Designer Drugs of (DREADDs) are also being considered for treatment of OSA through activation of pharyngeal muscles. DREADDs work by adding molecules (or the designer receptors) to specific neurons using viral vectors. These molecules can then be activated by designer drugs. Animal models have shown that treatment with DREADDs can improves pharyngeal muscle activity during sleep.
Physical Training
Performing exercises that work the upper airway muscles, such as didgeridoo playing and oropharyngeal exercises have been shown to reduce OSA severity and daytime sleepiness.
Treatments targeting respiratory arousal threshold
In most cases, individuals with OSA experience respiratory episodes that end in waking up or arousal from sleep. However, arousal is not necessary to reopen the upper airway. Continually waking up during sleep can make OSA and OSA symptoms worse. The level of negative pressure required to cause someone to wake up is the respiratory arousal threshold. The threshold can be determined using an epiglottic pressure catheter and PSG recording equipment. Current studies have not found that treatment with anti-insomnia therapies improve muscle activity in the upper airway. There are some concerns with using anti-insomnia drugs to target the respiratory arousal threshold, including extending respiratory events resulting in worse hypoxemia. However, treatment with eszopiclone, zopiclone and trazodone have shown to reduce the severity of OSA without increasing the risk of hypoxemia. Eszopiclone specifically reduced AHI for individuals with low arousal thresholds.