Sleep Apnea - what you need to know

Sleep apnea is one of the most serious medical conditions that often goes undiagnosed.

It is estimated that up to 30% of Canadians suffer from it, yet only 6.4% have recognized the diagnosis.

What is it?
Sleep apnea is a serious condition in which a person’s breathing is repeatedly interrupted during the night.  During normal sleep, air moves in an unobstructed, regular rhythm, through the upper airway, the throat and into and out of the lungs.  With obstructive sleep apnea (OSA), airway blockages, usually from soft tissue collapse, prevent the normal regular breathing rhythm

What are the symptoms?
The main symptoms of OSA are 

• loud snoring,
• fatigue, and 
• daytime sleepiness. 

However, some people have no symptoms or may not recognize that they have symptoms.

Other symptoms may include one or more of the following:

• Restless sleep
• Awakening with choking, gasping, or smothering
• Morning headaches, dry mouth, or sore throat
• Waking up to urinate more than once per night 
• Feeling unrested and groggy in the morning - “brain fog”
• Fatigue, low energy, memory challenges with difficulty concentrating

Perhaps the best way to determine risk is the use of the STOP-BANG questionnaire which uses a series of questions and results of physical measurements to calculate the risk for sleep apnea in adults aged 18 and older.
Snoring – Do you snore loudly (loud enough to be heard through closed doors)?
Tired – Do you often feel tired, fatigued or sleepy during the daytime?
Observed – Has anyone observed you stop breathing or choking/gasping during your sleep?
Pressure – Do you have or are being treated for high blood pressure?
Body mass index (BMI) – Body mass index more than 35kg/m2?
Age – Age older than 50?
Neck circumference – Neck size 17 inches or larger for males or 16 inches or larger for females?
Gender – Male?
​
Positive answers to the above questions are then used to determine risk:
Low risk – Yes to 0 to 2 questions
Intermediate risk – Yes to 3 to 4 questions
High risk – Yes to 5 to 8 questions

• OR yes to 2 or more of 4 STOP questions + male gender
• OR yes to 2 or more of 4 STOP questions + BMI > 35kg/m2
• OR yes to 2 or more of 4 STOP questions + neck circumference ≥ 17 inches for males or ≥ 16 inches for females

How common is it?
In 2017, 6.4% of Canadians self-reported a diagnosis of sleep apnea through the Canadian Health Measures Survey (CHMS) - this was more than double the rate reported in 2009.
In the US, using the broadest criteria is estimated that 20-30% of men and 10-15% of women have sleep apnea.   
In all likelihood, sleep apnea is under-diagnosed - using the STOP-BANG risk tool, the CHMS found that nearly one-third (30%) of Canadian adults were considered to be at intermediate or high risk for sleep apnea - 15% were high risk and 15% were moderate risk.

Rates are increasing along with the rates of obesity.

What are the risk factors?

• Age – sleep apnea is more common as you age
• Obesity - the link between excess weight and sleep apnea is well established. People who are overweight are more likely to have extra tissue in the back of their throat, which can fall down over the airway and block the flow of air into the lungs while they sleep.
• Male sex – men are twice as likely as women to have sleep apnea
• Having a large neck size (greater than 17” in men; 16” in women
• Drugs and/or Alcohol – increases the risk of sleep apnea as you may not awaken to open the airway
• Airway abnormalities - large tonsils, large tongue, deviated septum

What happens if it is left untreated?
The initial consequences of untreated sleep apnea are daytime sleepiness and difficulty concentrating results in increased errors and accidents.  People with severe sleep apnea are two to three times more likely to have a motor vehicle accident - this represents an impact on morbidity and mortality that is similar to the cardiovascular sequelae of OSA.

Over time untreated sleep apnea increase risk for cardiovascular disease, high blood pressure, abnormal heart rhythms, heart attack and stroke.

People with OSA have higher rates Insulin resistance and Type II Diabetes.  This association is partly manifested by the shared risk factor of obesity, but also appears to be independent.  In one study, patients with severe OSA had a 30% higher risk of diabetes even after controlling for age, obesity, pre-existing cardiovascular disease. 
The physiological mechanisms underlying this risk are likely related to the increase in oxidative stress caused by lack of oxygen as well as activation of the sympathetic nervous system (with the insulin resistance effects of adrenaline and cortisol).

For patients with existing metabolic syndrome - OSA is associated with poorer metabolic biomarkers: increased glucose, triglycerides, inflammatory markers, and overall increased cardiovascular risk.

Nonalcoholic fatty liver disease (NAFLD) - given the increased risk of metabolic syndrome with OSA and the shared risk factors between NAFLD and metabolic dysfunction -   OSA appears to contribute to the development and severity of nonalcoholic fatty liver disease (NAFLD), independent of shared risk factors such as obesity.

Mortality - Severe OSA increases the risk of death by 2-3 time independent of other risk factors - interestingly an increased risk of mortality does not appear to be present for untreated mild OSA.  What isn’t completely clear is how treatment of severe OSA affects the risk of mortality.

Diagnosis:
Once suspected due to witnessed apneic episodes, loud snoring, daytime sleepiness, resistant hypertension, or ineffective sleep - the next step is to get a sleep assessment.

The gold standard is the polysomnogram - done overnight in a sleep lab (and requiring a referral from your physician), it measures  breathing effort and airflow, blood oxygen level, heart rate and rhythm, duration of the various stages of sleep, body position, and movement of the arms/legs.

A more accessible alternative not requiring physician referral is a Level III sleep study - using portable devices that can be used at home.

Is it reversible?
This depends primarily on the underlying cause of the sleep apnea - if the primary cause is obesity then weight loss can improve symptoms and lead to a cure.  

Brain damage caused by severe sleep apnea is reversible.  A 2017 neuroimaging study is the first to show that white matter damage caused by severe obstructive sleep apnea can be reversed by continuous positive airway pressure therapy.

There is high quality evidence that in most adults positive airway pressure therapy reduces the frequency of respiratory events during sleep, decreases daytime sleepiness, improves systemic blood pressure (BP), lowers the risk of crashes, improves erectile dysfunction, and improves quality of life across a range of disease severities.

Unfortunately to date there have been no studies that have demonstrated that treatment improves mortality.

What are the treatments?

• Weight loss — Weight loss may be helpful for obese or overweight patients.
• Avoid alcohol and other sedatives — Alcohol can worsen sleepiness, potentially increasing the risk of accidents or injury. People with OSA are often counseled to drink little to no alcohol, even during the daytime. Similarly, people who take anti-anxiety medications or sedatives to sleep should speak with their healthcare provider about the safety of these medications.
• Stop Smoking
• Adjust sleep position — Adjusting sleep position to stay off the back may help improve sleep quality in people with sleep apnea, but this is difficult to maintain and is rarely an adequate solution.
• Continuous positive airway pressure (CPAP) — The most effective treatment for sleep apnea uses air pressure from a mechanical device to keep the upper airway open during sleep. A CPAP device (figure 3) uses an air-tight attachment to the nose, typically a mask, connected to a tube and a blower which generates the pressure [3]. Devices that fit comfortably into the nasal opening, rather than over the nose, are also available. CPAP should be used any time the person sleeps (day or night).  Continued follow up with a healthcare provider helps to ensure that the treatment is effective and comfortable. “The best CPAP device is the one you’re going to use.”
• Dental devices — A dental device, called an oral appliance or mandibular advancement device, can reposition the jaw (mandible), bringing the tongue and soft palate forward as well. This may relieve obstruction in some people [4].  This treatment is excellent for reducing snoring, although the effect on OSA is sometimes more limited [4]. As a result, dental devices are best used for mild cases of OSA when relief of snoring is the main goal. Failure to tolerate and accept CPAP is another indication for dental devices. While dental devices are not as effective as CPAP for OSA, some patients prefer a dental device to CPAP. Side effects of dental devices are generally minor but may include changes to the bite with prolonged use.
• Surgical treatment — Surgery is an alternative therapy for patients who cannot tolerate or do not improve with nonsurgical treatments such as CPAP or oral devices.  The most common surgical procedures for sleep apnea:
  • ​​Nasal surgery: Correction of nasal problems such as a deviated septum.
  • Uvulopalatopharyngoplasty (UPPP): A procedure that removes soft tissue on the back of the throat and palate, increasing the width of the airway at the opening of the throat. UPPP alone has limited success rates (less than 50 percent) and people can relapse
  • ​Mandibular maxillomandibular advancement surgery: Surgery to correct certain facial problems or throat obstructions that contribute to sleep apnea. MMA may have a higher success rate, particularly in people with abnormal jaw (maxilla and mandible) anatomy, but it is the most complicated procedure.

References:
https://www.uptodate.com/contents/sleep-apnea-in-adults-beyond-the-basics?search=sleep%20apnea&topicRef=7683&source=see_link
https://open.alberta.ca/publications/level-i-and-level-iii-sleep-studies
Canadian Thoracic Society Guidelines: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3070752/pdf/crj18025.pdf
American Academy of Sleep Science: http://jcsm.aasm.org/ViewAbstract.aspx?pid=31513

https://www.health.harvard.edu/blog/weight-loss-breathing-devices-still-best-for-treating-obstructive-sleep-apnea-201310026713

https://aasm.org/brain-damage-caused-by-severe-sleep-apnea-is-reversible/

https://www.webmd.com/sleep-disorders/sleep-apnea/sleep-apnea
STOP-Bang Questionnaire. Property of University Health Network, for further info: www.stopbang.ca modified from Chung F., et al. Anesthesiology. 2008. Vol. 108: 812-821; Chung F., et al. British Journal of Anaesthesia. 2012. Vol. 108:768-75; Chung F., et al. Obesity Surgery. 2013. Vol. 23: 2050-2057; Chung F., et al. Journal of Clinical Sleep Medicine. 2014.