History
Professor Colin Sullivan first developed the Continuous Positive Airway Pressure (CPAP) system at Royal Prince Alfred Hospital in Sydney, Australia, in 1981.
A continuous positive airway pressure (CPAP) machine was initially used mainly by patients for the treatment of sleep apnea at home, but now is in widespread use across intensive care units as a form of ventilation. Obstructive sleep apnea occurs when the upper airway becomes narrow as the muscles relax naturally during sleep. This reduces oxygen in the blood and causes arousal from sleep. The CPAP machine stops this by delivering a stream of compressed air through a hose to a nasal pillow, nose mask or full-face mask, this keeps the airway unobstructed(keeping it open under air pressure) so that unobstructed breathing becomes possible, reducing and/or preventing apneas and hypopneas. It is very important to understand, however, that it is the air pressure, and not the movement of the air, that prevents the apneas. When the machine is turned on, but prior to the mask being placed on the head, a flow of air comes through the mask. After the mask is placed on the head, it is sealed to the face and the air stops flowing. This has the additional benefit of reducing or eliminating the extremely loud snoring that sometimes accompanies sleep apnea.
The CPAP machine blows air at a prescribed pressure (also called titrated pressure). The necessary pressure is usually determined by a sleep physician after review of a study supervised by a sleep technician during an overnight study (polysomnography) in a sleep laboratory. The titrated pressure is the pressure of air at which most (if not all) apneas and hypopneas have been prevented, and it is usually measured in centimetres of water (cm H2O). The pressure required by most patients with sleep apnea ranges between 6 and 14 cm H2O. A typical CPAP machine can deliver pressures between 4 and 20 cm H2O. Specialized units can deliver pressures up to 25 or 30 cm H2O.
CPAP treatment can be highly effective in treatment of obstructive sleep apnea. For some patients, the improvement in the quality of sleep and quality of life due to CPAP treatment will be noticed after a single night's use. Often, the patient's sleep partner also benefits from markedly improved sleep quality, due to the diminishing of the patient's loud snoring.
Given that sleep apnea is a chronic health issue and doesn't go away, ongoing care is needed to maintain CPAP therapy. Based on the study of cognitive behavioral therapy, ongoing chronic care management is the best way to help patients continue therapy by educating them on the health risks of sleep apnea and providing motivation and support.
* APAP or AutoPAP or AutoCPAP (Automatic Positive Airway Pressure) automatically titrates, or tunes, the amount of pressure delivered to the patient to the minimum required to maintain an unobstructed airway on a breath-by-breath basis by measuring the resistance in the patient's breathing, thereby giving the patient the precise pressure required at a given moment and avoiding the compromise of fixed pressure.
Bi-level pressure devices
* VPAP or BiPAP (Variable/Bilevel Positive Airway Pressure) provides two levels of pressure: Inspiratory Positive Airway Pressure (IPAP) and a lower Expiratory Positive Airway Pressure (EPAP) for easier exhalation. (Some people use the term BPAP to parallel the terms APAP and CPAP.)
Modes
+ S (Spontaneous) - In spontaneous mode the device triggers IPAP when flow sensors detect spontaneous inspiratory effort and then cycles back to EPAP.
+ T (Timed) - In timed mode the IPAP/EPAP cycling is purely machine-triggered, at a set rate, typically expressed in breaths per minute (BPM).
+ S/T (Spontaneous/Timed) - Like spontaneous mode, the device triggers to IPAP on patient inspiratory effort. But in spontaneous/timed mode a "backup" rate is also set to ensure that patients still receives a minimum number of breaths per minute if they fail to breathe spontaneously.
What is Sleep Apnea?
The Greek word "apnea" literally means "without breath." There are three types of apnea: obstructive, central, and mixed; of the three, obstructive is the most common. Despite the difference in the root cause of each type, in all three, people with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night and often for a minute or longer.
Sleep apnea (or sleep apnoea in British English) is a sleep disorder characterized by pauses in breathing during sleep. Each episode, called an apnea, lasts long enough so that one or more breaths are missed, and such episodes occur repeatedly throughout sleep.[1] The standard definition of any apneic event includes a minimum 10-second interval between breaths, with either a neurological arousal (a 3-second or greater shift in EEG frequency, measured at C3, C4, O1, or O2) or a blood oxygen desaturation of 3–4% or greater, or both arousal and desaturation. Sleep apnea is diagnosed with an overnight sleep test called a polysomnogram, or a "sleep study".
Clinically significant levels of sleep apnea are defined as five or more episodes per hour of any type of apnea (from the polysomnogram). There are three distinct forms of sleep apnea: central, obstructive, and complex (i.e., a combination of central and obstructive) constituting 0.4%, 84% and 15% of cases respectively.[2] Breathing is interrupted by the lack of respiratory effort in central sleep apnea; in obstructive sleep apnea, breathing is interrupted by a physical block to airflow despite respiratory effort. In complex (or "mixed") sleep apnea, there is a transition from central to obstructive features during the events themselves.
Regardless of type, the individual with sleep apnea is rarely aware of having difficulty breathing, even upon awakening. Sleep apnea is recognized as a problem by others witnessing the individual during episodes or is suspected because of its effects on the body. Symptoms may be present for years (or even decades) without identification, during which time the sufferer may become conditioned to the daytime sleepiness and fatigue associated with significant levels of sleep disturbance.
Obstructive sleep apnea (OSA) is the most common category of sleep-disordered breathing. The muscle tone of the body ordinarily relaxes during sleep, and at the level of the throat the human airway is composed of collapsible walls of soft tissue which can obstruct breathing during sleep. Mild occasional sleep apnea, such as many people experience during an upper respiratory infection, may not be important, but chronic severe obstructive sleep apnea requires treatment to prevent low blood oxygen (hypoxemia), sleep deprivation, and other complications. The most serious complication is a severe form of congestive heart failure called cor pulmonale.
Individuals with low muscle tone and soft tissue around the airway (e.g., because of obesity) and structural features that give rise to a narrowed airway are at high risk for obstructive sleep apnea. The elderly are more likely to have OSA than young people. Men are more likely to suffer sleep apnea than women and children are, though it is not uncommon in the latter two population groups.
The risk of OSA rises with increasing body weight, active smoking and age. In addition, patients with diabetes or "borderline" diabetes have up to three times the risk of having OSA.
Common symptoms include loud snoring, restless sleep, and sleepiness during the daytime. Diagnostic tests include home oximetry or polysomnography in a sleep clinic.
Some treatments involve lifestyle changes, such as avoiding alcohol or muscle relaxants, losing weight, and quitting smoking. Many people benefit from sleeping at a 30-degree elevation of the upper body or higher, as if in a recliner. Doing so helps prevent the gravitational collapse of the airway. Lateral positions (sleeping on a side), as opposed to supine positions (sleeping on the back), are also recommended as a treatment for sleep apnea, largely because the gravitational component is smaller in the lateral position. Some people benefit from various kinds of oral appliances to keep the airway open during sleep. "Breathing machines" like the continuous positive airway pressure (CPAP) may help. There are also surgical procedures to remove and tighten tissue and widen the airway.
As already mentioned, snoring is a common finding in people with this syndrome. Snoring is the turbulent sound of air moving through the back of the mouth, nose, and throat. Although not everyone who snores is experiencing difficulty breathing, snoring in combination with other conditions such as overweight and obesity has been found to be highly predictive of OSA risk.The loudness of the snoring is not indicative of the severity of obstruction, however. If the upper airways are tremendously obstructed, there may not be enough air movement to make much sound. Even the loudest snoring does not mean that an individual has sleep apnea syndrome. The sign that is most suggestive of sleep apneas occurs when snoring stops. If both snoring and breathing stop while the person's chest and body try to breathe, that is literally a description of an event in obstructive sleep apnea syndrome. When breathing starts again, there is typically a deep gasp and then the resumption of snoring.
Other indicators include (but are not limited to): hypersomnolence, obesity, large neck circumference (16 in (410 mm) in women, 17 in (430 mm) in men), enlarged tonsils and large tongue volume, micrognathia, morning headaches, irritability/mood-swings/depression, learning and/or memory difficulties, and sexual dysfunction.
The term "sleep-disordered breathing" is commonly used in the U.S. to describe the full range of breathing problems during sleep in which not enough air reaches the lungs. Sleep-disordered breathing is associated with an increased risk of cardiovascular disease, stroke, high blood pressure, arrhythmias, diabetes, and sleep deprived driving accidents.When high blood pressure is caused by OSA, it is distinctive in that, unlike most cases of high blood pressure, the readings do not drop significantly when the individual is sleeping. Stroke is associated with obstructive sleep apnea.Sleep apnea sufferers also have a 30% higher risk of heart attack or premature death than those unaffected.
In pure central sleep apnea or Cheyne-Stokes respiration, the brain's respiratory control centers are imbalanced during sleep. Blood levels of carbon dioxide, and the neurological feedback mechanism that monitors them, do not react quickly enough to maintain an even respiratory rate, with the entire system cycling between apnea and hyperpnea, even during wakefulness. The sleeper stops breathing and then starts again. There is no effort made to breathe during the pause in breathing: there are no chest movements and no struggling. After the episode of apnea, breathing may be faster for a period of time, a compensatory mechanism to blow off retained waste gases and absorb more oxygen.While sleeping, a normal individual is "at rest" as far as cardiovascular workload is concerned. Breathing is regular in a healthy person during sleep, and oxygen levels and carbon dioxide levels in the bloodstream stay fairly constant. The respiratory drive is so strong that even conscious efforts to hold one's breath do not overcome it. Any sudden drop in oxygen or excess of carbon dioxide (even if tiny) strongly stimulates the brain's respiratory centers to breathe.
In central sleep apnea, the basic neurological controls for breathing rate malfunction and fail to give the signal to inhale, causing the individual to miss one or more cycles of breathing. If the pause in breathing is long enough, the percentage of oxygen in the circulation will drop to a lower than normal level (hypoxaemia) and the concentration of carbon dioxide will build to a higher than normal level (hypercapnia). In turn, these conditions of hypoxia and hypercapnia will trigger additional effects on the body. Brain cells need constant oxygen to live, and if the level of blood oxygen goes low enough for long enough, the consequences of brain damage and even death will occur. Fortunately, central sleep apnea is more often a chronic condition that causes much milder effects than sudden death. The exact effects of the condition will depend on how severe the apnea is and on the individual characteristics of the person having the apnea. Several examples are discussed below.
In any person, hypoxia and hypercapnia have certain common effects on the body. The heart rate will increase, unless there are such severe co-existing problems with the heart muscle itself or the autonomic nervous system that makes this compensatory increase impossible. The more translucent areas of the body will show a bluish or dusky cast from cyanosis, which is the change in hue that occurs owing to lack of oxygen in the blood ("turning blue"). Overdoses of drugs that are respiratory depressants (such as heroin, and other opiates) kill by damping the activity of the brain's respiratory control centers. In central sleep apnea, the effects of sleep alone can remove the brain's mandate for the body to breathe. Even in severe cases of central sleep apnea, the effects almost always result in pauses that make breathing irregular, rather than cause the total cessation of breathing.
* Normal Respiratory Drive: After exhalation, the blood level of oxygen decreases and that of carbon dioxide increases. Exchange of gases with a lungful of fresh air is necessary to replenish oxygen and rid the bloodstream of built-up carbon dioxide. Oxygen and carbon dioxide receptors in the blood stream (called chemoreceptors) send nerve impulses to the brain, which then signals reflex opening of the larynx (so that the opening between the vocal cords enlarges) and movements of the rib cage muscles and diaphragm. These muscles expand the thorax (chest cavity) so that a partial vacuum is made within the lungs and air rushes in to fill it.
* Physiologic effects of central apnea: During central apneas, the central respiratory drive is absent, and the brain does not respond to changing blood levels of the respiratory gases. No breath is taken despite the normal signals to inhale. The immediate effects of central sleep apnea on the body depend on how long the failure to breathe endures. At worst, central sleep apnea may cause sudden death. Short of death, drops in blood oxygen may trigger seizures, even in the absence of epilepsy. In people with epilepsy, the hypoxia caused by apnea may trigger seizures that had previously been well controlled by medications. In other words, a seizure disorder may become unstable in the presence of sleep apnea. In adults with coronary artery disease, a severe drop in blood oxygen level can cause angina, arrhythmias, or heart attacks (myocardial infarction). Longstanding recurrent episodes of apnea, over months and years, may cause an increase in carbon dioxide levels that can change the pH of the blood enough to cause a metabolic acidosis.
Mixed apnea and complex sleep apnea
Some people with sleep apnea have a combination of both types. When obstructive sleep apnea syndrome is severe and longstanding, episodes of central apnea sometimes develop. The exact mechanism of the loss of central respiratory drive during sleep in OSA is unknown but is most commonly related to acid-base and CO2 feedback malfunctions stemming from heart failure. There is a constellation of diseases and symptoms relating to body mass, cardiovascular, respiratory, and occasionally, neurological dysfunction that have a synergistic effect in sleep-disordered breathing. The presence of central sleep apnea without an obstructive component is a common result of chronic opiate use owing to the characteristic respiratory depression caused by large doses of narcotics.
Complex sleep apnea has recently been described by researchers as a novel presentation of sleep apnea. Patients with complex sleep apnea exhibit OSA, but upon application of positive airway pressure the patient exhibits persistent central sleep apnea. This central apnea is most commonly noted while on CPAP therapy after the obstructive component has been eliminated. This has long been seen in sleep laboratories and has historically been managed either by CPAP or BiLevel therapy. Adaptive servo-ventilation (ASV) modes of therapy have been introduced to attempt to manage this complex sleep apnea. Studies have demonstrated marginally superior performance of the adaptive servo ventilators in treating Cheyne-Stokes breathing; however, no longitudinal studies have yet been published, nor have any results been generated that suggest any differential outcomes versus standard CPAP therapy.
The most common treatment for sleep apnea is the use of a continuous positive airway pressure (CPAP) device, which 'splints' the patient's airway open during sleep by means of a flow of pressurized air into the throat. The CPAP machine assists only inhaling, whereas a BiPAP machine assists with both inhaling and exhaling and is used in more severe cases.
In addition to CPAP, dentists specializing in sleep disorders can prescribe Oral Appliance Therapy (OAT). The oral appliance is a custom-made mouthpiece that shifts the lower jaw forward, opening up the airway. OAT is usually successful in patients with mild to moderate obstructive sleep apnea.OAT is a relatively new treatment option for sleep apnea in the United States, but it is much more common in Canada and Europe. Its use has led to increasing recognition of the importance of upper airway anatomy in the pathophysiology of OSA
In mild cases of obstructive sleep apnea, use of a specially shaped pillow or shirt may reduce sleep apnea episodes, usually by causing users to sleep on the side instead of on the back or in a reclining position instead of flat. In an individual with either central, obstructive or mixed sleep apnea, these low doses may be enough to cause life-threatening irregularities in breathing or collapses in a patient’s airways. Use of analgesics and sedatives in these patients postoperatively should therefore be minimized or avoided.
Sleep apnea patients undergoing any medical treatment must make sure his or her doctor and/or anesthetist are informed about their condition. Alternate and emergency procedures may be necessary to maintain the airway of sleep apnea patients. A 2005 study in the British Medical Journal found that learning and practicing the didgeridoo helped reduce snoring and sleep apnea as well as daytime sleepiness. This appears to work by strengthening muscles in the upper airway, thus reducing their tendency to collapse during sleep.
Herbal treatments for sleep apnea are also available. In 2008 herbalist Steve Frank applied to patent an "herbal preparation for relief of sleep apnea contains lobelia and/or lobelia extract material acting as a respiratory stimulant." Other herbs counteract nausea and further increase respiration during sleep. The treatment is taken in capsule form, circumventing the need for a CPAP machine and requiring no masks or oral appliances.
Epidemiology
It is estimated that 20 million Americans are affected by sleep apnea. That would represent more than 6.5%, or nearly 1 in 15 Americans, making sleep apnea as prevalent as asthma or diabetes. It is also estimated that 85-90 percent of individuals affected are undiagnosed and untreated. The Wisconsin Sleep Cohort Study found that, among the middle-aged, nine percent of women and 24 percent of men had sleep apnea.
The costs of untreated sleep apnea reach further than just health issues. It is estimated that the average untreated sleep apnea patient's health care costs $1,336 more than an individual without sleep apnea. If approximations are correct, 17 million untreated individuals account for $22,712 million,or almost 23 billion in health care costs.
History
The first reports in the medical literature of what is now called obstructive sleep apnea date only from 1965, when it was independently described by French and German investigators. However, the clinical picture of this condition has long been recognized as a character trait, without an understanding of the disease process. The term "Pickwickian syndrome" that is sometimes used for the syndrome was coined by the famous early 20th century physician, William Osler, who must have been a reader of Charles Dickens. The description of Joe, "the fat boy" in Dickens's novel The Pickwick Papers, is an accurate clinical picture of an adult with obstructive sleep apnea syndrome.
The early reports of obstructive sleep apnea in the medical literature described individuals who were very severely affected, often presenting with severe hypoxemia, hypercapnia and congestive heart failure. Tracheostomy was the recommended treatment and, though it could be life-saving, postoperative complications in the stoma were frequent in these very obese and short-necked individual.
The management of obstructive sleep apnea was revolutionized with the introduction of continuous positive airway pressure (CPAP), first described in 1981 by Colin Sullivan and associates in Sydney, Australia. The first models were bulky and noisy, but the design was rapidly improved and by the late 1980s CPAP was widely adopted. The availability of an effective treatment stimulated an aggressive search for affected individuals and led to the establishment of hundreds of specialized clinics dedicated to the diagnosis and treatment of sleep disorders. Though many types of sleep problems are recognized, the vast majority of patients attending these centers have sleep-disordered breathing.
Obstructive sleep apnea (OSA) is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses and closes during sleep. In central sleep apnea, the airway is not blocked but the brain fails to signal the muscles to breathe. Mixed apnea, as the name implies, is a combination of the two. With each apnea event, the brain briefly arouses people with sleep apnea in order for them to resume breathing, but consequently sleep is extremely fragmented and of poor quality.
Sleep apnea is very common, as common as adult diabetes, and affects more than twelve million Americans, according to the National Institutes of Health. Risk factors include being male, overweight, and over the age of forty, but sleep apnea can strike anyone at any age, even children. Yet still because of the lack of awareness by the public and healthcare professionals, the vast majority remain undiagnosed and therefore untreated, despite the fact that this serious disorder can have significant consequences.
Untreated, sleep apnea can cause high blood pressure and other cardiovascular disease, memory problems, weight gain,
In some people, the windpipe that brings air into the body is blocked during sleep. This keeps the lungs from getting enough air. This is called obstructive sleep apnea. People who have sleep apnea stop breathing for 10 to 30 seconds at a time while they are sleeping. These stops can happen up to 400 times every night. The consequences of these disturbances can be serious and sometimes life-threatening.
what happens when you
Stop Breathing During Sleep?
If you have sleep apnea, you stop breathing during sleep, and the balance of oxygen and carbon dioxide in the blood is upset. This imbalance stimulates the brain to restart the breathing process. The brain signals you to wake up so that the muscles of the tongue and throat can increase the size of the airway. Then, carbon dioxide can escape, and oxygen can enter the airway. These waking episodes are necessary to restart breathing (and to save your life), but you become sleep-deprived.
