Normal sleep/wakefulness in adults has distinct stages numbered 1 to 4, REM sleep, non-REM sleep (NREM) and consciousness. The deeper stages (3 to 4) of REM sleep are required for the physically restorative effects of sleep, and in pre-adolescents are the focus of release for human growth hormone. Stages 2 and REM, which combined are 70% of an average person's total sleep time, are more associated with mental recovery and maintenance. During REM sleep in particular, muscle tone of the throat and neck, as well as the vast majority of all skeletal muscles, is almost completely attenuated, allowing the tongue and soft palate/oropharynx to relax, and in the case of sleep apnea, to impede the flow of air to a degree ranging from light snoring to complete collapse. In the cases where airflow is reduced to a degree where blood oxygen levels fall, or the physical exertion to breathe is too great, neurological mechanisms trigger a sudden interruption of sleep, called a neurological arousal(electroencephalographic arousal). These arousals rarely result in complete awakening, but can have a significant negative effect on the restorative quality of sleep. In significant cases of obstructive sleep apnea, one consequence is sleep deprivation due to the repetitive disruption and recovery of sleep activity. This sleep interruption in stages 3 and 4 (also collectively called slow-wave sleep), can interfere with normal growth patterns, healing, and immune response, especially in children and young adults.
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Showing posts with label Sleep Apnea. Show all posts
Showing posts with label Sleep Apnea. Show all posts
Wednesday, March 31, 2010
Pathophysiology of obstructive sleep apnea
In obstructive sleep apnea, breathing is interrupted by a physical block to airflow, despite the effort to breathe. It is characterized by pauses in breathing during sleep. These episodes, called apneas (literally, "without breath"), each last long enough that one or more breaths are missed, and occur repeatedly throughout sleep.
Prognosis
Sleep apnea has a strong association with several diseases, particularly those related to the heart and circulation.
Adverse Effects of Sleep Apnea on Heart and Circulation
Researchers are intensively investigating why a problem in the upper airways is associated with serious conditions of the heart and circulatory system. Here are some of their findings:
* Major known risk factors for hypertension and heart disease (obesity, smoking, and alcohol abuse) are associated with sleep apnea. These factors, however, do not explain all cases of higher heart-related risks in people with sleep apnea. For example, among overweight people, those who have sleep apneas have a greater risk of heart problems than those without them.
* When breathing stops during episodes of apnea, carbon dioxide levels in the blood increase and oxygen levels drop. This effect may trigger a cascade of physical and chemical events that can then increase risk for heart problems.
* Apnea also causes decreased levels of the gas nitric oxide (NO), a potent substance that causes blood vessels to be elastic and expand. NO plays a crucial role in blood pressure control and heart health.
* Apnea may also increase levels of a substance called angiotensin-converting enzyme (ACE), which is known to play a role in high blood pressure and congestive heart failure.
* Researchers have reported high levels of certain immune factors called tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) in people with sleep apnea, particularly those who are obese. High levels of TNF-alpha and IL-6 produce a damaging inflammatory response, which can harm cells in the body, including those in the arteries. Elevated TNF-alpha may be associated with fatigue, shortness of breath, and a diminished heart-pumping action.
At this time, however, evidence of a clear causal relationship with any of these health problems is still weak. Some studies have found no significant independent risk for heart disease from obstructive sleep apnea. The following are some discussions on the possible effects of apnea on specific health problems.
Adverse Effects of Sleep Apnea on Heart and Circulation
Researchers are intensively investigating why a problem in the upper airways is associated with serious conditions of the heart and circulatory system. Here are some of their findings:
* Major known risk factors for hypertension and heart disease (obesity, smoking, and alcohol abuse) are associated with sleep apnea. These factors, however, do not explain all cases of higher heart-related risks in people with sleep apnea. For example, among overweight people, those who have sleep apneas have a greater risk of heart problems than those without them.
* When breathing stops during episodes of apnea, carbon dioxide levels in the blood increase and oxygen levels drop. This effect may trigger a cascade of physical and chemical events that can then increase risk for heart problems.
* Apnea also causes decreased levels of the gas nitric oxide (NO), a potent substance that causes blood vessels to be elastic and expand. NO plays a crucial role in blood pressure control and heart health.
* Apnea may also increase levels of a substance called angiotensin-converting enzyme (ACE), which is known to play a role in high blood pressure and congestive heart failure.
* Researchers have reported high levels of certain immune factors called tumor necrosis factor-alpha (TNF-alpha) and interleukin 6 (IL-6) in people with sleep apnea, particularly those who are obese. High levels of TNF-alpha and IL-6 produce a damaging inflammatory response, which can harm cells in the body, including those in the arteries. Elevated TNF-alpha may be associated with fatigue, shortness of breath, and a diminished heart-pumping action.
At this time, however, evidence of a clear causal relationship with any of these health problems is still weak. Some studies have found no significant independent risk for heart disease from obstructive sleep apnea. The following are some discussions on the possible effects of apnea on specific health problems.
Sunday, March 28, 2010
Aetiology of OSA
Snoring is a result of incomplete pharyngeal obstruction.
In children :
OSA in children is usually due to large tonsils and adenoids. There is no relation, however, between tonsils and adenoid size and the degree of OSA. This is probably due to the combined effects of muscle tone, pharyngeal size and adenotonsillar hypertrophy.
High risk groups include children with craniofacial anomalies, cerebral palsy, muscular dystrophy and Down syndrome.
Children with OSA are not usually obese, but OSA does occur frequently in morbidly obese children and adolescents.
Source : The American Sleep Apnea Association (ASAA)
Turbulent airflow and subsequent progressive vibratory trauma to the soft tissues of the upper airway are important factors that contribute to the condition.
Anatomic obstruction leads to increased negative inspiratory pressure, which propagates further airway collapse, turbulence, and noise.
The imbalance between the forces that act to maintain airway patency (the force of the pharyngeal muscles) and the negative inspiratory forces generated by the diaphragm is thought to be the primary etiology of anatomic obstruction in OSA.
In OSA, the tongue contacts the soft palate and posterior pharyngeal wall in the presence of lateral collapse of the pharynx, generating occlusion.
Significant factors that contribute to this condition include
- obesity
- redundant tissue in the neck
- retrognathia
- craniofacial anomalies
- anatomic abnormalities of the nasal airway (eg, septal deviation, inferior turbinate hypertrophy, nasal-valve narrowing, adenoid hypertrophy)
- Alcohol and other sedatives may increase the severity of OSA.
- Data from a recent meta-analysis by Rada also suggested a causal relationship between OSA and head and neck cancer (which may first manifest as OSA).
In children :
OSA in children is usually due to large tonsils and adenoids. There is no relation, however, between tonsils and adenoid size and the degree of OSA. This is probably due to the combined effects of muscle tone, pharyngeal size and adenotonsillar hypertrophy.
High risk groups include children with craniofacial anomalies, cerebral palsy, muscular dystrophy and Down syndrome.
Children with OSA are not usually obese, but OSA does occur frequently in morbidly obese children and adolescents.
Source : The American Sleep Apnea Association (ASAA)
Treatment of Sleep Apnea
Whom to Treat
There is evidence obtained from robust randomized controlled trials (RCT) that treatment improves symptoms, sleepiness, driving, cognition, mood, quality of life, and blood pressure in patients who have an Epworth score of >11, troublesome sleepiness while driving or working, and >15 apneas + hypopneas per hour of sleep. For those with similar degrees of sleepiness and 5–15 events per hour of sleep, RCTs indicate improvements in symptoms, including subjective sleepiness, with less strong evidence indicating gains in cognition and quality of life. There is no evidence of blood pressure improvements in this group, nor is there is evidence that treating nonsleepy subjects improves their symptoms, function, or blood pressure. Thus, treatment cannot be advocated for this large group.
How to Treat
All patients diagnosed with OSAHS should have the condition and its significance explained to them and to their partner. This should be accompanied by provision of written and/or web-based information and a discussion of the implications of the local regulations for driving. Rectifiable predispositions should be discussed; this often includes weight loss and sometimes reduction of alcohol consumption to reduce caloric intake and because alcohol acutely decreases upper-airway dilating muscle tone, thus predisposing to obstructed breathing. Sedative drugs, which also affect airway tone, should be carefully withdrawn.
Continuous Positive Airway Pressure (CPAP)
CPAP therapy works by blowing the airway open during sleep, usually with pressures of 5–20 cmHg. CPAP has been shown in randomized placebo-controlled trials to improve breathing during sleep, sleep quality, sleepiness, blood pressure, vigilance, cognition, and driving ability, as well as mood and quality of life in patients with OSAHS. However, this is obtrusive therapy, and care must be taken to explain the need for the treatment to the patient and his/her partner, and to support all patients on CPAP intensively, providing access to telephone support and regular follow-up. Initiation should include finding the most comfortable mask from the ranges of several manufacturers and trying the system for at least 30 min during the daytime to prepare for the overnight trial. An overnight monitored trial of CPAP is used to identify the pressure required to keep the patient's airway patent. The development of pressure-varying CPAP machines may make the in-lab CPAP night trial unnecessary, but treatment must be initiated in a supportive environment. Thereafter, patients can be treated with fixed-pressure CPAP machines set at the determined pressure or by a self-adjusting, intelligent CPAP device. The main side effect of CPAP is airway drying, which can be countered using an integral heated humidifier. CPAP use, like that of all therapies, is imperfect, but around 94% of patients with severe OSAHS are still using their therapy after 5 years on objective monitoring.
Mandibular Repositioning Splint (MRS)
Also called oral devices, MRSs work by holding the lower jaw and the tongue forward, thereby widening the pharyngeal airway. MRSs have been shown in RCTs to improve OSAHS patients' breathing during sleep, daytime somnolence, and blood pressure. As there are many devices of differing design with unknown relative efficacy, these results cannot be generalized to all MRSs. Self-reports of the use of devices long-term suggest high dropout rates.
Surgery
Four forms of surgery have a role in OSAHS, although it must always be remembered that these patients have a raised perioperative risk. Bariatric surgery can be curative in the morbidly obese. Tonsillectomy can be highly effective in children but rarely in adults. Tracheostomy is curative but rarely used because of the associated morbidity; nevertheless, it should not be overlooked in extremely advanced cases. Jaw advancement surgery—particularly maxillo-mandibular osteotomy—is effective in those with retrognathia (posterior displacement of the mandible) and should be particularly considered in young and thin patients. There is no robust evidence that pharyngeal surgery, including uvulopalatopharyngoplasty (whether by scalpel, laser, or thermal techniques) helps OSAHS.
Drugs
Unfortunately, no drugs are clinically useful in the prevention or reduction of apneas and hypopneas. A marginal improvement in sleepiness in patients who remain sleepy despite CPAP can be produced by modafinil, but the clinical value is debatable and the financial cost significant.
Choice of Treatment
CPAP and MRS are the two most widely used and best evidence-based therapies. Direct comparisons in RCTs indicate better outcomes with CPAP in terms of apneas and hypopneas, nocturnal oxygenation, symptoms, quality of life, mood, and vigilance. Adherence to CPAP is generally better than to an MRS, and there is evidence that CPAP improves driving, whereas there are no such data on MRSs, Thus, CPAP is the current treatment of choice. However, MRSs are evidence-based second-line therapy in those who fail CPAP. In younger, thinner patients, maxillo-mandibular advancement should be considered.
There is evidence obtained from robust randomized controlled trials (RCT) that treatment improves symptoms, sleepiness, driving, cognition, mood, quality of life, and blood pressure in patients who have an Epworth score of >11, troublesome sleepiness while driving or working, and >15 apneas + hypopneas per hour of sleep. For those with similar degrees of sleepiness and 5–15 events per hour of sleep, RCTs indicate improvements in symptoms, including subjective sleepiness, with less strong evidence indicating gains in cognition and quality of life. There is no evidence of blood pressure improvements in this group, nor is there is evidence that treating nonsleepy subjects improves their symptoms, function, or blood pressure. Thus, treatment cannot be advocated for this large group.
How to Treat
All patients diagnosed with OSAHS should have the condition and its significance explained to them and to their partner. This should be accompanied by provision of written and/or web-based information and a discussion of the implications of the local regulations for driving. Rectifiable predispositions should be discussed; this often includes weight loss and sometimes reduction of alcohol consumption to reduce caloric intake and because alcohol acutely decreases upper-airway dilating muscle tone, thus predisposing to obstructed breathing. Sedative drugs, which also affect airway tone, should be carefully withdrawn.
Continuous Positive Airway Pressure (CPAP)
CPAP therapy works by blowing the airway open during sleep, usually with pressures of 5–20 cmHg. CPAP has been shown in randomized placebo-controlled trials to improve breathing during sleep, sleep quality, sleepiness, blood pressure, vigilance, cognition, and driving ability, as well as mood and quality of life in patients with OSAHS. However, this is obtrusive therapy, and care must be taken to explain the need for the treatment to the patient and his/her partner, and to support all patients on CPAP intensively, providing access to telephone support and regular follow-up. Initiation should include finding the most comfortable mask from the ranges of several manufacturers and trying the system for at least 30 min during the daytime to prepare for the overnight trial. An overnight monitored trial of CPAP is used to identify the pressure required to keep the patient's airway patent. The development of pressure-varying CPAP machines may make the in-lab CPAP night trial unnecessary, but treatment must be initiated in a supportive environment. Thereafter, patients can be treated with fixed-pressure CPAP machines set at the determined pressure or by a self-adjusting, intelligent CPAP device. The main side effect of CPAP is airway drying, which can be countered using an integral heated humidifier. CPAP use, like that of all therapies, is imperfect, but around 94% of patients with severe OSAHS are still using their therapy after 5 years on objective monitoring.
Mandibular Repositioning Splint (MRS)
Also called oral devices, MRSs work by holding the lower jaw and the tongue forward, thereby widening the pharyngeal airway. MRSs have been shown in RCTs to improve OSAHS patients' breathing during sleep, daytime somnolence, and blood pressure. As there are many devices of differing design with unknown relative efficacy, these results cannot be generalized to all MRSs. Self-reports of the use of devices long-term suggest high dropout rates.
Surgery
Four forms of surgery have a role in OSAHS, although it must always be remembered that these patients have a raised perioperative risk. Bariatric surgery can be curative in the morbidly obese. Tonsillectomy can be highly effective in children but rarely in adults. Tracheostomy is curative but rarely used because of the associated morbidity; nevertheless, it should not be overlooked in extremely advanced cases. Jaw advancement surgery—particularly maxillo-mandibular osteotomy—is effective in those with retrognathia (posterior displacement of the mandible) and should be particularly considered in young and thin patients. There is no robust evidence that pharyngeal surgery, including uvulopalatopharyngoplasty (whether by scalpel, laser, or thermal techniques) helps OSAHS.
Drugs
Unfortunately, no drugs are clinically useful in the prevention or reduction of apneas and hypopneas. A marginal improvement in sleepiness in patients who remain sleepy despite CPAP can be produced by modafinil, but the clinical value is debatable and the financial cost significant.
Choice of Treatment
CPAP and MRS are the two most widely used and best evidence-based therapies. Direct comparisons in RCTs indicate better outcomes with CPAP in terms of apneas and hypopneas, nocturnal oxygenation, symptoms, quality of life, mood, and vigilance. Adherence to CPAP is generally better than to an MRS, and there is evidence that CPAP improves driving, whereas there are no such data on MRSs, Thus, CPAP is the current treatment of choice. However, MRSs are evidence-based second-line therapy in those who fail CPAP. In younger, thinner patients, maxillo-mandibular advancement should be considered.
Saturday, March 27, 2010
Sign and Symptoms of Sleep Apnea
Sign and Symptoms of Sleep Apnea
Signs:
1. Abnormal heart rhythm and increase blood pressure (caused by decrease oxygen levels in blood.)
2. Prolonged sleep apnea leads to heart failure and malfunction of the lungs
Symptoms:
1. Snore: loudest when sleep on the back and lessen when sleep on the side. (Prominent in Obstructive Sleep Apnea)
2. Observed episodes of breathing cessation during sleep (choking and gasping)
3. Abrupt awakenings accompanied by shortness of breath
4. Breathing become slow and shallow
5. Excessive daytime sleepiness especially when inactive (hypersomnia).
6. Morning headache
7. Memory and learning problems and not able to concentrate
8. Feeling irritable, depressed, or having mood swings or personality changes
9. Sex drives reduced.
10. Urination at night
11. A dry throat when you wake up
12. Difficulty staying asleep (insomnia)
p/s: partners or family members will notice these before the patient.
In children
1. Hyperactivity, poor school performance, and aggressiveness
2. Unusual sleeping positions, bedwetting, and may breathe through their mouths instead of their noses during the day.
References:
http://www.mayoclinic.com/health/sleep-apnea/DS00148/METHOD=print
http://www.nhlbi.nih.gov/health/dci/Diseases/SleepApnea/SleepApnea_Signs.html
The Merick Manual of Medical Information
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