What is Obstructive Sleep Apnea?
Obstructive sleep apnea (OSA) is a common but significant sleep-related breathing disorder characterized by interruptions of sleep caused by partial or complete airway obstructions while sleeping. An apnea is a complete cessation of airflow. A hypopnea is a partial cessation of airflow.
The muscles and tissue within the upper airway relax and lose some of the muscle tension important for maintaining patency or remaining open while sleeping. As the tissue and muscles relax gravity often assists further and creates an obstruction or blockage for proper airflow to occur. Snoring develops as some of the relaxed tissue vibrate within the upper airway.
As the airway is obstructed (either partially or completely), air being inhaled cannot reach the lungs which can then cause a decrease in the level of oxygen within the blood. The decrease in blood oxygen levels is called hypoxemia. With oxygen levels beginning to decrease, the brain and heart react. Often a person’s heart rate increases as a means to try to increase the amount of blood being delivered and the brain experiences an arousal or brief awakening from sleep. Frequently those experiencing sleep apnea gasp or choke as a result from airway obstruction occurring; the body reacts by trying to regain normal breathing for proper oxygenation.
The repetitive cycle that occurs with obstructive sleep apnea (respiratory event, decrease in oxygenation, arousal from sleep) can leave a person feeling fatigued even following a full night’s sleep. Throughout the day a person may also experience morning headaches, difficulty concentrating or excessive daytime sleepiness. In addition, the chronic deficiency of oxygen during sleep can result in additional health risks such as high blood pressure, cardiovascular disease, stroke, diabetes, obesity and depression.
Symptoms of Obstructive Sleep Apnea
As a sleep-related breathing disorder, OSA shares symptoms with other disorders in this category, like central sleep apnea and complex sleep apnea. Complex sleep apnea is a combination of central and obstructive sleep apnea—breathing interruptions result from both airway obstruction and neuromuscular problems.
Sleep apnea can cause sleep-related laryngospasm, in which the sleeper wakes up suddenly with a feeling of suffocation. Any attempts to speak come out as a wheeze. People who have these spasms often have gastroesophageal reflux, which could indicate a link between these conditions.
Other symptoms of obstructive sleep apnea include:
Symptoms of sleep-related breathing disorders like OSA worsen during the winter. This may be due to allergies and seasonal weight gain (many people get heavier in the winter). Weather conditions such as high atmospheric pressure (more common in winter), high humidity (more common in summer) and carbon monoxide (more common in urban areas) can worsen sleep apnea symptoms. Cold and flu season peaks during the winter months, so seasonal increases in respiratory infections and irritation may trigger OSA symptoms.
Who has obstructive sleep apnea? Research suggests that around 40 million Americans experience obstructive sleep apnea. Men are more susceptible to sleep apnea than women. Nearly 20 percent of men and nine percent of women experience sleep apena at some point in their lives. Moderate-to-severe apnea affects nine percent of males and four percent of females. Two percent of children are also affected by sleep apnea, mostly infants under one year of age.
Experts attribute increasing rates of sleep apnea to improved diagnostics and increasing obesity rates. In the early 90s, approximately 3 percent of the general population had sleep apnea.
Sleep apnea is most prevalent in middle-aged males. Males are between two and three times as likely to develop apnea than women. Males typically have a larger neck circumference and a longer pharyngeal airway, which make them more susceptible to sleep apnea.
The incidence of obstructive sleep apnea increases with age and peaks between ages 40 and 60. After age 60, sleep apnea rates begin to decrease.
Pregnant women have higher rates of sleep apnea. Nearly 80 percent of pregnant women experience symptoms of sleep apnea at some point in their pregnancy, usually in the third trimester. This seems to be due to a combination if enlarged blood vessels, hormonal changes, and weight gain.
Smokers are three times as likely to develop apnea as nonsmokers, because smoking causes increased upper airway inflammation and fluid retention. The increased risk is reversible; once a smoker quits, their sleep apnea risk decreases.
Obstructive Sleep Apnea Risk Factors
Obstructive sleep apnea is often associated with carrying excess weight. Excess body weight expands soft tissues in the throat and mouth, which relax during sleep and obstruct the airway. Because OSA is linked to obesity, conditions that increase the risk of obesity, like metabolic syndrome and diabetes, are associated with an increased risk for OSA. People with cleft lips and cleft palates may have higher rates of sleep-related breathing disorders, including OSA.
In some cases, OSA exists without obesity or another related health condition. There may also be a genetic component to OSA risk.
Other Risk Factors
Neck circumference or size. For men neck circumference of 17 inches or more and for women 16 inches or more. Increased tissue around the neck can increase obstructive events while sleeping.
Age. Obstructive sleep apnea is most prevalent in middle aged people between the ages of 40-60 years old.
Gender. Males are 2-3 times more likely to develop obstructive sleep apnea than females; males typically have a larger neck circumference than females.
Family history/Anatomical component. Those with a direct relative are at risk for having obstructive sleep apnea. Anatomical structure also plays a part having sleep apnea. Some people may have large tonsils or a large tongue for their mouth which creates an environment for sleep apnea to be more prevalent. Other anatomical factors include having a recessed chin (craniofacial retrognathism), deviated septum, cleft lips, cleft palates or a large tongue.
Pregnancy. Women, particular in their third trimester are at a higher risk for sleep apnea due to additional weight
Opioid Use. Opioid use can greatly impact the presence of sleep apnea. Though more commonly found as a risk factor for central sleep apnea, opioid use can cause obstructive sleep apnea as well due to the relaxing of the soft tissues within the throat.
Sleep apnea is highly underdiagnosed. According to the National Institutes of Health, only 25 percent of adults with sleep apnea symptoms sought medical attention. Indeed, one of the goals of the government’s Healthy People 2020 initiative is to raise this percentage. People experiencing symptoms of obstructive sleep apnea like excessive daytime tiredness, frequent night arousals accompanied by a choking or gasping, or unexplained weight gain should talk to a doctor about sleep apnea.
There are two kinds of sleep studies for which a person can undergo for accurate data collection.
Overnight Lab Test
The first is an in-lab overnight sleep study and provides extensive information for the sleep physician to review. An overnight polysomnogram includes a stay in a sleep facility for a night where specially trained technicians apply numerous electrodes for monitoring purposes. The technician observes the patient throughout the night paying close attention to brain activity, heart rate, oxygen levels as well as possible respiratory events such as hypopnea or apnea indicative of obstructive sleep apnea.
In addition, the sleep technician monitors any muscle movements that may occur and snoring. In-lab overnight sleep studies are often used in patients that have more complex past medical histories or a previous diagnosis of sleep apnea.
The second kind of sleep study is a home sleep apnea test. As the name implies, this test can be conducted within the patient’s home without the need of an overnight stay in a sleep facility.
For patients without complicated medical histories and a high risk for obstructive sleep apnea, a home sleep test may be a viable option. Home sleep studies are not as comprehensive an an in-lab test but can provide sleep physicians the necessary data needed for proper diagnosis of obstructive sleep apnea.
Following the sleep study the physician reviews the information and can make an accurate diagnosis. The Apnea-Hypopnea Index (AHI) was developed as a means to quantify the severity of sleep disordered breathing in patients.
The AHI is the sum of how many apneas and hypopneas the patient experienced on average per hour during the sleep study. An AHI less than 5 is considered to be within normal parameters. Mild sleep apnea is categorized by an AHI of 5-15. Moderate sleep apnea is within an AHI of 15-30 and severe sleep apnea is an AHI greater than 30. The numerical value indicates how many times on average the patient experienced an apnea or hypopnea; an AHI of 17 means the patient had difficulties breathing an average of 17 times per hour.
The most common treatment for obstructive sleep apnea is continuous positive airway pressure, known as CPAP. In CPAP therapy, a bedside machine generates a continuous flow of positive air pressure. The machine connects to a mask worn on the face overnight. The machine supplies positive airway pressure that keeps the airway open during sleep, reducing or eliminating apneas (breathing interruptions) during sleep.
Masks come in a wide variety of styles and sizes to allow for some personalization. There are nasal masks (those that just go over the nose) nasal pillows (small cushions that rest just inside the nostrils) as well as full face masks (a mask that allows for nose or mouth breathing). Machines come with a humidifier chamber to allow for humidified air to prevent drying while using the device.
An alternative to CPAP is BiPAP, or bilevel positive airway pressure. BiPAP utilizes two different pressures rather than one continuous flow of pressure like CPAP. For some people breathing out against a set pressure can be difficult or uncomfortable so BiLevel machines allow for users to breathe out against a lower pressure and breathe in with a higher set pressure. Both pressures work to resolve hypopnea and apnea and any desaturations that occur during sleep.
Dental devices are another option for some people with mild obstructive sleep apnea or for those with primary snoring. Dental devices are custom fit to the person and require a specially trained dentist or orthodontist. Most dental devices work by helping to better align the lower jaw as a means to aid in maintaining an open airway while asleep. These devices are called mandibular advancement devices and look very similar to a standard mouthguard. Other devices work to splint the tongue so as to prevent it from causing obstruction in the airway.
Surgery for obstructive sleep apnea is available and includes uvulopalatopharyngoplasty or UPPP which removes the soft tissues within the throat causing obstructions while sleeping.
Positional therapy includes avoidance of supine sleep. Suggestions include sewing a tennis ball or block of foam to the back of sleeping clothes to prevent a person from rolling supine and supporting side lying for reduction of snore and sleep related breathing.
Weight loss is a very effective sleep apnea treatment and overall health benefit to reduce risks of diabetes, cardiovascular disease and other disorders. However it is important that while working to lose weight, treatment for obstructive sleep apnea continues whether that be a dental device, CPAP or BiPAP. Following significant weight loss, the need for treatment can be re-evaluated but only while under the direction of a certified sleep physician or primary care physician or other medical professional with certified sleep experience.
Drugs cannot correct sleep-related breathing disorders, but may treat some of the underlying causes of sleep apnea, including narrowed or restricted airways. Domperidone (normally used to suppress vomiting and nausea) and decongestants pseudoephedrine or phenylephrine may help open airways to reduce sleep apnea symptoms.
The drug acetazolamide is used to treat altitude sickness, and research suggests it might benefit people with sleep apnea. The drug, sold under the brand name Diamox, helps increase oxygen levels in the bloodstream. When people ascend to alpine levels, they sometimes have trouble getting enough oxygen. Sleep apnea produces some of the same effects, and Swiss scientists found acetazolamide may help, although this is not yet an accepted treatment.
Research shows that melatonin may have beneficial effects for people with sleep apnea. Melatonin can help induce sleep and regulate sleep patterns. Per research, it may also help reduce oxidative stress in the body caused by sleep apnea.