Sleep apnea, sometimes spelled "apnoea" - one of the most potentially dangerous sleep disorders - is when the patient stops breathing during regularly sleep. The term apnea literarily means "without breath". The period of stoppage is usually short (a few seconds) before breathing resumes. The seriousness of apnea varies considerably and depends on how long the sleep stoppages are how many happen. Experts estimate apnea affects 1 in 15 people or 18 million Americans. Men are more susceptible to sleep apnea than women. "All-cause" mortality risk increases significantly with apnea. The worse the apnea, the higher the risk of death from a number of factors.
There are three types of sleep apnea: central sleep apnea , obstructive sleep apnea and complex sleep apnea. Obstructive sleep apnea is the most common type.
Obstructive sleep apnea (OSA) is an obstruction of the airway passage that results in a decreased level of oxygen in the blood. The obstructions cause a choking or gasping along with loud snoring during sleep. These choking and gasping episodes briefly arouses the person and can happen as frequently as 20 to 30 times per hour. For this reason a person with sleep apnea cannot get a good night’s rest. Apnea can also cause a headache in the morning, a dry mouth, tiredness during the day, and reduced libido. Central sleep apnea has similar characteristics to OSA, but lacks the loud snoring aspect. In both cases the person awakes suddenly during the night choking or gasping for air.
The reasons why some people are afflicted with sleep apnea are not well understood. Researchers believe there are genetic components. Identification of a single gene is not likely and the current theory points to multiple genes as a plausible cause. One study demonstrated a correlation between obstructive sleep apnea and developing hypertension. The researchers followed individuals with OSA and those that had more than 15 obstructive wake-ups per hour were more likely to develop hypertension within the next 4 years. They also found that those who did not receive treatment had an increase risk for cardiovascular morbidity and mortality. A more recent study suggests that the relationship between apnea and hypertension is because of obesity. Obesity is a major factor in both conditions, while apnea might sometimes be the cause of the hypertension, this condition is more likely caused by high body weight and other factors. High blood pressure and apnea are "co-morbidities". People with moderate-to-severe OSA can have extensive brain changes, possibly because of the repeated hypoxia. A study presented at the International Stroke Conference in 2012 found that apnea patients have a higher risk of strokes and brain lesions. Many apnea patients also have abnormal swallowing while asleep, although this problem does not typically reach a magnitude where it is considered clinically significant.
Sleep deprivation and apnea can put stress on the body and raise blood pressure and cause the release of cytokines by the immune system, putting further strain on the cardiovascular system. Sleep-disordered breathing may cause abnormal lipid metabolism, and SDB and deprivation may be tied to metabolic syndrome, which affects tens of millions of Americans. Apnea increases the risk of hypertension, regardless of the person’s age, sex, or level of obesity. An article by Greek doctors even playfully called apnea and resistant hypertension “sparring partners”.
Obstructive sleep apnea is correlated with metabolic syndrome, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1978322/ although some of the components of metabolic syndrome – diabetes and high cholesterol – did not show correlation with apnea at levels high enough to be considered statistically significant.
Central sleep apnea is much less common, but potentially very dangerous. Central sleep apnea is caused by the failure of brain to transmit signals to the body to breathe, in contrast to obstructive sleep apnea is due to a physical block that obstructs air flow to the lungs.
Cheyne-Stokes respiration is when there is a crescendo - decrescendo pattern of respiration. It occurs in people with congestive heart failure or stroke. Drug or substance abuse, especially over consumption of a respiratory depressant drug may cause central sleep apnea. Alcohol, opiates, benzodiazepines, barbiturates, and some kinds of tranquilizers are respiratory depressants. Breathing at high altitude also causes sleep apnea. In some cases the causes are not known, these cases are “idiopathic central sleep apnea”.
People with certain heart and neuromuscular disorders are also in danger of central sleep apnea.
During an incident of central sleep apnea if the intervals in breathing are too spread apart, the oxygen level in the bloodstream falls below the normal level and the amount of carbon dioxide increases. Thess abnormal blood levels can cause negative effects on a range of organs; if oxygen level remains low for a long time it can lead to brain damage or even death. The severity of the apnea and the physical fitness of the patient are factors in how well the body can withstand the apnea. Lack of oxygen can cause seizures even in people who have no history of epilepsy and in people with diagnosed epilepsy, but who have it under control, it can cause seizures again and for people with heart diseases it can cause arrhythmias, angina or heart attack.
Complex sleep apnea is a combination of central and obstructive sleep apnea . During complex sleep apnea obstructive apnea and central apnea happen concurrently.
A related symptom some apnea sufferers get is sleep-related laryngospasm. The sleeper wakes up suddenly and feeling alarmed that he or she is suffocating. Any attempts to speak come out as a wheeze. People who have these spasms often have gastro-oesophageal reflux, too, leading doctors to hypothesize a connection where the stomach acids reach the larynx and irritate the tissue. It is also connected to surgery on the larynx.
Cleft lips and palates are the most common birth defects and may affect sleep breathing. Surgical repair of the airway can help, although sometimes people have apnea and other problems even after surgery.
Treatment of Obstructive Sleep Apnea
The most common treatment for obstructive sleep apnea is termed continuous positive airway pressure or CPAP. The positive pressure is generated by a machine that sits next to the bed and has a mask connected to it that the person wears while sleeping. It forces pressure into the nose and mouth so the airway does not collapse and the person sleeps without choking or gasping awakenings. While CPAP machines increase the quality of sleep, excessive sleepiness does not always go away, in these people modafinil or armodafinil may be used as a treatment. These drugs help to maintain wakefulness during the day.
CPAP is the most common treatment, but surgery called uvulopalatopharyngoplasty is also an option. Your physician may recommend weight loss, avoidance of alcohol/sedatives, or sleeping in a position other than the back. Removing the tonsils or adenoids also can relieve apnea, especially in children. During the diagnosis process there is a series of tests and the test scores as a measure of severity will determine which course of treatment should be taken. (A sample Berlin Questionairre can be seen here.) For those having trouble with CPAP upon exhaling against the positive pressure there is a modified machine called bilevel positive airway pressure or BPAP and this decreases the pressure during exhalation and increases the pressure during inhalation. There have been several pharmacologic treatments tested, but none of them have yielded results similar to treatment with positive airway pressure. If a person is unwilling or unable to use positive airway pressure machines, surgery is an option. The federal government publishes a guideline on "Diagnosis and treatment of obstructive apnea in adults."
Drugs are not used to directly treat apnea, but there is interest among researchers in developing pharmacological treatment that targets the anatomy and mechanism of the breathing system. A combination of domperidone (normally used to suppress vomiting and nausea) and the antihistimine pseudoephedrine has been tried in a study at a Department of Veterans Affairs hospital. There was also interest in replacing the pseudoephedrine with phenylephrine, a decongestant that is often used in place of pseudoephedrine. This idea was that these drugs would help open passageways for airflow.
Weight loss is often the best way to definitively reduce the effects of apnea, and one advantage is that the patient gets doesn't have to use the CPAP machine or a mouthguard, both of which tend to be abandoned by patients as being too bothersome.
In 2007 the professional journal Sleep featured a debate about whether mild apnea should be treated. The opposing view (that it should not be treated) rested on low patient compliance with CPAP and the fact that observations of people with mild to moderate apnea who do use the CPAP regularly do not show significant improvements in daytime sleepiness (objective or subjective) and blood pressure. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2564770/
The author of this article thinks mild apnea should be addressed by trying to get the sleeper to cut alcohol consumption, lose weight, and generally practice good sleep hygiene.
The article advocating treatment, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2564769/, stated that non-medical intervention is not sufficient and that measures of quality of life improvement due to CPAP are flawed.
Acetazolamide for Apnea
The drug acetazolamide is used to treat mountain sickness (which can include altitude insomnia) and research suggests it might help out people with 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. Apnea produces some of the same effects, and Swiss scientists found acetazolamide may help, although this is not yet an accepted treatment.
Treatment of Central Sleep Apnea
Numerous techniques can be used to treat central sleep apnea. . Reducing the consumption of respiratory suppressant drugs also helps. If the cause is due to a heart or a neuromuscular condition, treatment of the disorder can cure the apnea. Supplemental Oxygen and devices like CPAP machines, Bi-level positive airway pressure, Adaptive servo-ventilation help in supply of oxygen to the brain by aiding the respiratory process.
Sleeping in the lateral position on the back has been found to be helpful in cases of central sleep apnea. Medications like acerazlamide and theophyllinr lower the pH level of the blood and helps in respiration are used by some doctors to treat sleep apnea patients. People who display symptoms of central sleep apnea should consult a physician at the earliest since delays in treating this disease may lead to life threatening conditions.
Diagnosis and Warnings
Sleep apnea is highly undiagnosed. According to a National Health Institute estimate, only 25 percent of Americans with apnea symptoms sought medical attention over a 4-year period. Indeed, one of the goals of the government's Health People initiative is to raise this percentage.
A polysomnography is done to detect sleep apnea. In the test the heart, brain and lung activities are tested during sleep to check any abnormality. Oximetry might also be done to check the blood oxygen level during sleep. In some cases MRI might also be done.
If a person is experiencing excessive daytime tiredness along with frequent night arousals accompanied by a choking or gasping for air feeling, they should talk to their clinician about sleep apnea. Excessive tiredness can lead to many side effects such as endangering your life or others when driving. Severe mood changes, mental dysfunction, and libido reduction are also associated with sleep apnea.
The Apnea-Hyponea Index was created to quantify the severity of apnea. There are difference indices; the simplest counts the number of breathing stoppages per hour, with under 5 considered normal (no apnea). Mild apnea is 5 to 15 incidences per hour, moderate 15-30, and severe greater than 30. There is some controversey because different ways of measuring apnea lead to different results; this is an area where diagnostic standards could be improved.
State laws may require that doctors who know about excessivly sleepy people (clincal name for condition: excessive daytime sleepiness) report them to the motor vehicle bureau. The American Thoracic Society (a professional medical group) does not recommend physicians interfere with driving privileges unless the patient has been in a crash or some other event indicates particularly high risk. The society recommends doctors report patients only if they have been in an accident, has apnea that cannot be treated, or refuses treatment within two months of diagnosis.
Neurogenic tachypnea is a disorder of breathing - is when people breath fast and shallow. Neurogenic tachypnea is sometimes the beginnings of neurodegenerative disease. Which is why it is important that your doctor check you out.
Recent epidemiological work has shown that apnea symptoms are worse during the winter. Part of the the increase in disordered breathing 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) make apnea worse. Colds and general irritation of the respiratory system are worse in the winter, which can exacerbate apnea symptoms.
The University of Michigan made this video that gives a good overview of apnea:
The website UpToDate has an article covering diagnosis and treatment.
Pagel, J., 2008, The Burden of Obstructive Sleep Apnea and Associated
Excessive Sleepiness, The Journal of Family Practice, 57(8):S3-S7
Riha, R., Diefenbach, K., Jennum, P., McNicholas, W., 2008, Genetic Aspects of Hypertension and Metabolic Disease in the Obstructive Sleep Apnoea-Hypoponea, Sleep Medicine, 12:49-63
Smith, I., Lasserson, T., Wright, J., 2006, Drug Therapy for Obstructive Sleep Apnea in Adults, Cochrane Database of Systematic Reviews, Issue 3
Black, J. and Hirshkowitz, M., 2005, Modafinil for Treatment of
Residual Excessive Sleepiness in Nasal Continuous Positive Airway
Pressure-Treated Obstructive Sleep Apnea/Hypopnea Syndrome, 28(4):464-471
A 2007 article in the Journal of the American Academy of Pain Medicine talks about the connection between opioid medication and sleep apnea. Researchers looked at patients taking opioids for chronic pain and found they had a higher incidence of apnea. This is not surprising as opioids relax the muscles and that includes the throat area. However, these patients did not have the crescendo-decrescendo breath size pattern characteristic of people with central sleep apnea.
There is some evidence that the antidepressant medication mirtazapine (Remeron) helps relieve apnea. This is the most effective drug for apnea found so far, but the evidence is based only on a small trial. Mirtazapine is not used widely in apnea treatment.
Apnea also leads to memory problems. For a long time doctors thought the decline in short term memory ability was due to sleep deprivation. New findings indicate the apnea actually causes shrinkage in areas of the brain important to memory. Use of CPAP machines and regular exercise seems to help.
"O Sleep, rest of all things, mildest of the gods, balm of the soul..."
(Iris to Hypnos. Ovid, Metamorphoses)