Sleep Apnea:

What is Sleep Apnea (SA), or 'Apnoea'?

SA is a sleep disorder characterised by abnormal pauses in breathing, or instances of abnormally low breathing, during sleep; each pause in breathing is called an Apnea and can last from a few seconds to minutes, and may occur from 5 to more than 30 times an hour; each abnormally low breathing event is called an 'Hypopnea'; there are three forms of SA, Central SA (CSA), Obstructive SA (OSA) and Complex SA (ComSA) or Mixed SA (MSA), which is a combination of CSA and OSA; in CSA breathing is interrupted by a lack of respiratory effort; in OSA breathing is interrupted by a physical block to airflow despite respiratory effort and snoring is common.

Regardless of the type, an individual with SA is rarely aware of having difficulty breathing, even upon awakening; SA is usually recognised as a problem by others witnessing the individual during episodes, or is suspected because of its effects on the body 'Sequelae'; symptoms may be present for years without identification, during which time the sufferer may become conditioned to the daytime sleepiness and fatigue associated with significant levels of sleep disturbance; SA affects not only adults but some children as well.
OSA is the most common category of Sleep Disordered Breathing (SDB) the muscle tone of the body normally 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 SA (MOSA), such as many people experience during an upper respiratory infection, may not be important, but Chronic Severe Obstructive SA (CSOSA) requires treatment to prevent low blood oxygen 'Hypoxemia', sleep deprivation and other complications.

Central Sleep Apnea (CSA) or Cheyne Stokes Respiration (CSR):

In pure CSA, 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 'Hyperpnea' 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 CSA, 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, CSA 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 SA is and on the individual characteristics of the person having the SA.

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 and turns the skin bluish; 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 CSA, the effects of sleep alone can remove the brain's mandate for the body to breathe.

Normal Respiratory Drive:

After exhalation, the blood level of oxygen decreases and that of carbon dioxide increases; the 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 Sleep Apnea (CSA):

During CSA, 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 CSA on the body depend on how long the failure to breathe endures; at worst CSA 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 SA.

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; it also causes a slight struggling that the person is not aware of; if not recognised by anyone awake it may lead to death, or any other problems; this is similar to an Asthma attack but not quite the same, it gives you a feeling as if you are being strangled by someone.

Mixed Apnea and Complex Sleep Apnea, a mix of (Obstructive Sleep Apnea (OSA) and Central Sleep Apnea (CSA):

Some people with SA have a combination of both types; when the OSA syndrome is severe and longstanding, episodes of CSA 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 SDB; in some cases, a side effect from the lack of sleep is a mild case of EDS where the subject has had minimal sleep and this extreme fatigue over time takes its toll on the subject; the presence of CSA without an obstructive component is a common result of chronic opiate use, or abuse, owing to the characteristic respiratory depression caused by large doses of narcotics.

What are the Symptoms of Sleep Apnea (SA)?

The risk of OSA rises with increased body weight, active smoking and age; in addition, patients with Diabetes are up to three times more likely to suffer from OSA; people with low muscle tone and soft tissue around the airway, such as with those who are clinically obese, and structural features that give rise to a narrowed airway are at high risk of OSA and the elderly and men are more likely to have OSA than young people and women; although unfortunately, it is not uncommon in women and children.

Common symptoms include loud snoring, restless sleep and sleepiness during the daytime and sufferers complain about EDS, fatigue and impaired alertness, a slower reaction time and vision problems; early reports of OSA in the medical literature described individuals who were very severely affected, as often being affected with severe Hypoxemia, Hypercapnia and Congestive Heart Failure.

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 the SA syndrome; the sign that is most suggestive of SAs occurs when the snoring stops.

Due to the disruption in daytime cognitive state, behavioral effects are also present, which include moodiness and belligerence, as well as a decrease in attentiveness and drive; these effects become very hard to deal with, thus the development of depression may transpire and unfortunately, due to the many factors that could lead to some of the effects previously listed, some patients are not aware that they suffer from SA and are either misdiagnosed, or just ignore the symptoms altogether.

Other indicators include, but are not limited to, Hypersomnolence, Obesity BMI >30, 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 SDB is commonly to describe the full range of breathing problems during sleep in which not enough air reaches the lungs 'Hypopnea' and 'Apnea'; SDB 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 'Essential Hypertension', the readings do not drop significantly when the individual is sleeping.

How is Sleep Apnea (SA) Diagnosed?

The diagnosis of SA is based on the conjoint evaluation of clinical symptoms, such as excessive daytime sleepiness and fatigue, and of the results of a formal sleep study 'Polysomnography or a 'Reduced Channels Home Based test; the latter aims at establishing an objective diagnosis indicator linked to the quantity of Apneic events per hour of SA Hypopnea Index (SAHI) or Respiratory Disturbance Index (RDI), associated to a formal threshold, above which a patient is considered as suffering from SA and the severity of their SA can then be quantified.

Nevertheless, due to the number and variability in the actual symptoms and nature of Apneic events, such as Hypopnea vs SA and CSA vs OSA, the variability of patients' physiologies and the intrinsic imperfections of the experimental setups and methods, this field is opened to debate; within this context, the definition of an Apneic event depends on several factors, such as the patient's age, and account for this variability through a multi criteria decision rule described in several, sometimes conflicting, guidelines.

One example of a commonly adopted definition of an Apnea, for an adult, 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 to 4)% or greater, or both arousal and desaturation.

Oximetry, which may be performed overnight in a patient's home, is an easier alternative to formal sleep study 'Polysomnography; in one study, normal overnight oximetry was very sensitive and so if normal, SA was unlikely; in addition, home oximetry may be equally effective in guiding prescription for automatically self adjusting continuous positive airway pressure.

Patients are often examined using 'Standard Test Batteries' in order to further identify parts of the brain that are affected by SA; the tests have shown that certain parts of the brain cause different effects; the 'Executive Functioning' part of the brain affects the way the patient plans and initiates tasks; the part of the brain that deals with attention causes difficulty in paying attention, working effectively and processing information when in a waking state and the part of the brain that uses memory and learning is also affected.

How is Sleep Apnea (SA) Treated?

Some treatments involve lifestyle changes, such as losing weight, quitting smoking, avoiding alcohol or muscle relaxants, sleeping pills and other sedatives, which can relax throat muscles, contributing to the collapse of the airway at night; therefore, treatment often starts with behavioral therapy; for mild cases of SA, physicians often recommend sleeping on one's side, as opposed to on one's back, which can prevent the tongue and palate from falling backwards in the throat and blocking the airway; this probably works owing to changes in the pulmonary oxygen stores.

Many people also 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, such as sleeping on a side, as opposed to supine positions, sleeping on the back, are also recommended as a treatment for SA, largely because the gravitational component is smaller in the lateral position.

The management of OSA was revolutionised with the introduction of the Continuous Positive Airway Pressure (CPAP), or Automatic Positive Airway Pressure (APAP), device, 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 specialised clinics dedicated to the diagnosis and treatment of sleep disorders; though many types of sleep problems are recognised, the vast majority of patients attending these centers have SDB; CPAP is the most consistently safe and effective treatment for OSA, but it is not a Panacea and people are less likely to use it in the long term.

For moderate to severe SA, the most common treatment is the use of a CPAP device, which splints the patient's airway open during sleep by means of a flow of pressurised air into the throat; the patient typically wears a plastic facial mask, which is connected by a flexible tube to a small bedside CPAP machine; the CPAP machine generates the required air pressure to keep the patient's airways open during sleep; advanced models may warm or humidify the air and monitor the patient's breathing to ensure proper treatment; although CPAP therapy is extremely effective in reducing Apneas and less expensive than other treatments, some patients find it extremely uncomfortable and many patients refuse to continue the therapy or fail to use their CPAP machines on a nightly basis.

Some patients with complex SA exhibit OSA, but upon application of positive airway pressure exhibit persistent CSA; this CSA is most commonly noted whilst 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 ComSA.

In addition to CPAP, dentists specialising 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 OSA.

Several inpatient and outpatient procedures use sedation; many drugs and agents used during surgery to relieve pain and to depress consciousness remain in the body at low amounts for hours or even days afterwards; in an individual with either CSA, OSA or MSA, these low doses may be enough to cause life threatening irregularities in breathing or collapses in a patientís airways; use of analgesics and sedatives in these patients postoperatively should therefore be minimised or avoided.

The Pillar Procedure is a minimally invasive treatment for snoring and OSA; during this procedure, three to six+ dacron, the material used in permanent sutures, strips are inserted into the soft palate, using a modified syringe and local anesthetic; while the procedure was initially approved for the insertion of three 'Pillars' into the soft palate, it was found that there was a significant dosage response to more pillars, with appropriate candidates; after this brief and virtually painless outpatient operation, which usually lasts no more than 30 minutes, the soft palate is more rigid and snoring and SA can be reduced; this procedure addresses one of the most common causes of snoring and SA, the vibration or collapse of the soft palate, the soft part of the roof of the mouth; if there are other factors contributing to snoring or SA, such as the nasal airway or an enlarged tongue, it will likely need to be combined with other treatments to be more effective.

Surgical Treatments of Sleep Apnea (SA):

Several surgical procedures are used to treat SA, although they are normally a second line of treatment for those who reject CPAP treatment or are not helped by it; surgical treatment for OSA needs to be individualised in order to address all anatomical areas of obstruction; often, the correction of the nasal passages needs to be performed in addition to correction of the Oropharynx Passage; Septoplasty and Turbinate surgery may improve the nasal airway; Tonsillectomy and UvuloPalatoPharyngoplasty (UPPP or UP3) are available to address Pharyngeal Obstruction; Base of Tongue advancement by means of advancing the Genial Tubercle of the Mandible may help with the Lower Pharynx; a myriad of other techniques is available, including Hyoid Bone Myotomy and Suspension and various Radiofrequency technologies.

Other surgery options may attempt to shrink or stiffen excess tissue in the mouth or throat; procedures done at either a doctor's office or a hospital; small shots or other treatments, sometimes in a series, are used for shrinkage, while the insertion of a small piece of stiff plastic is used in the case of surgery whose goal is to stiffen tissues.

Maxillomandibular Advancement (MMA) is considered the most effective surgery for SA patients, because it increases the posterior airway space; the main benefit of the operation is that the oxygen saturation in the arterial blood increases and overall risks of MMA surgery are low.

Surgery on the mouth and throat, as well as dental surgery and procedures, can result in postoperative swelling of the lining of the mouth and other areas that affect the airway; even when the surgical procedure is designed to improve the airway, such as tonsillectomy and adenoidectomy or tongue reduction, swelling may negate some of the effects in the immediate postoperative period; however, once the swelling resolves and the palate becomes tightened by postoperative scarring, the full benefit of the surgery may be noticed.

Other Treatments of Sleep Apnea (SA):

Clinical studies have suggested that strengthening the muscles around the upper airway may combat SA; a 2009 study published in the American Journal of Respiratory and Clinical Care Medicine found that patients who practiced a series of tongue and throat exercises for 30 minutes a day showed a marked decline in SA symptoms after three months and sufferers experienced an average of 39% fewer Apnea episodes after successfully completing the treatments.

A 2005 study in the British Medical Journal found that learning and practicing the didgeridoo helped reduce snoring and SA as well as daytime sleepiness; this appears to work by strengthening muscles in the upper airway, thus reducing their tendency to collapse during sleep.

NB. All SA 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 SA patients; if an individual suspects he or she may have SA, communication with their doctor about possible preprocedure screening may be in order.

Strokes are associated with obstructive Sleep Apnea:

In the June 27, 2008, edition of the journal 'Neuroscience Letters', researchers revealed that people with OSA show tissue loss in brain regions that help store memory, thus linking OSA with memory loss; using Magnetic Resonance Imaging (MRI), the scientists discovered that SA patients' mammillary bodies were nearly 20% smaller, particularly on the left side; one of the key investigators hypothesized that repeated drops in oxygen lead to the brain injury.

Sleep Apnea Related Information Leaflet

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