Sleep Related Breathing Disorders

Sleep related breathing disorders are a group of disorders described by irregularities of respiration during sleep. The broad categories of sleep-related breathing disorders are Obstructive Sleep Apnea (OSA) syndromes, Central Sleep Apnea (CSA) syndromes, sleep-related hypoventilation syndromes, sleep-related hypoventilation resulting from a medical condition, and other sleep-related breathing disorders. Along with causing symptoms, these disorders may have long term adverse health consequences.    Correct diagnosis of the different types of sleep related breathing disorders is necessary in determining the approach to management. A sleep test is usally required to differentiate these conditions.

The dentist should diagnosis and manage these conditions in conjunction with a pulmonologist or sleep physician.

Sleep related breathing disorders are a group of disorders characterized by abnormalities of respiration during sleep. They are classified into 5 major groups.

Classification of sleep-related breathing disorders

  1. Obstructive sleep apnea syndromes
  • Adult obstructive sleep apnea (OSA)
  • Upper airway resistance syndrome (UARS)
  • Pediatric OSA
  1. Central sleep apnea syndromes
  • Primary central sleep apnea (CSA)
  • CSA resulting from Cheyne-Stokes breathing pattern (eg, in cardiac failure or stroke)
  • CSA resulting from high-altitude periodic breathing
  • CSA resulting from a medical condition
  • CSA resulting from a drug or a substance
  • Primary CSA of infancy
  1. Sleep-related hypoventilation resulting from a medical condition
  • Idiopathic sleep-related nonobstructive alveolar hypoventilation
  • Congenital central alveolar hypoventilation syndrome
  1. Sleep-related hypoventilation resulting from a medical condition
  • Obesity hypoventilation syndrome
  • Sleep-related hypoventilation resulting from pulmonary parenchymal or vascular pathology
  • Sleep-related hypoventilation resulting from lower airway obstruction
  • Sleep-related hypoventilation resulting from neuromuscular or chest wall disorders
  1. Other sleep-related breathing disorders

 Obstructive Sleep apnea

Obstructive Sleep Apnea (OSA) represents a spectrum of irregularity, ranging from upper airway resistance (UARS) to OSA syndrome. Described by the repetitive complete or partial collapse of the upper airway during sleep, causing apneas or hypopnea, OSA syndrome affects 2% to 4% of middle-aged adults.

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UARS is described by partial collapse of the upper airway, without the existence of obstructive apnea and hypopneas. UARS is thought to be an intermediate form of sleep related breathing disorder, between snoring and OSA. There is a rise in respiratory effort in an attempt to compensate for the decrease in airflow, which may lead to brief awakenings from sleep (cortical arousals) and other physiologic and clinical consequences similar to those seen in OSA. UARS is treated as part of the spectrum of OSA and not a separate entity.

Risk factors and consequences

Obesity is a major risk factor. However, OSA can also occurs in thin patients. Other important predisposing factors are male gender, family history of OSA, aging, craniofacial abnormalities, ethnicity, nasal obstruction, alcohol consumption, and cigarette smoking. Obstructive apneas and hypopneas result in irregular arterial blood gas abnormalities (hypoxemia and hypercapnia), brief awakening from sleep (cortical arousals), and surges of sympathetic nerve activity. These respiratory events can occur in any stages of sleep but are usually longer and associated with more sever oxygen desaturation when they occur in rapid eye movement (REM) sleep.

The symptoms of OSA include snoring, witnessed apnea, choking, nocturnal awakenings, and excessive daytime sleepiness, Insomnia, fragmented non-refreshing sleep, sweating during sleep, clouded intellect, poor concentration, depression and erectile dysfunction. OSA health consequences such a hypertension, metabolic dysfunction, cardiovascular disease, neurocognitive deficits, and motor vehicle accidents, sudden cardiac death, diabetes, obesity, atrial fibrillation, and stroke.

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Upper airway obstruction tends to unfold gradually over time as a result of factors such as obesity. As the severity of upper airway obstruction increases, so do the clinical consequences.

Diagnosis and management

The apnea-hypopnea index (AHI) refers to the total number of apnea and hypopnea episodes per hour of sleep. The AHI is derived from a sleep test and is the key measurement used to describe the presence and severity of OSA. The presence of OSA is defined by an AHI of more than 5 events per hour in association with symptoms (such as excessive daytime sleepiness). The American Academy of Sleep Medicine defines the following for level of sevitry of OSA based on AHI.

Mild is 5 to 15 events per hour

Moderate is 15 to 30 events per hour

Sever is more than 30 events per hour.

Treatment of OSA aims to reverse the clinical consequences and pathophysiology ramifications. The management options include weight loss, positional therapy, oral apnea appliances, continuous positive airway pressure (CPAP), and surgery.

Central Sleep Apnea

CSA is characterized by repeated episodes of absent or diminished respiratory effort, causing central apnea or central hypopneas. There is a problem with the communication from the brain to the respiration muscles.

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Risk factors and consequences

CSA is much less common in the general population that OSA.  CSA is more frequent in the elderly, in males, and in those with certain comorbidities (such as heart failure or stroke). Primary CSA can lead to insomnia and sleep fragmentation. Other symptoms include witnessed apneas, nocturnal awakenings, and excessive daytime sleepiness. However, a significant proportion of patients do not complain of these symptoms.

Diagnosis and management

The diagnosis of CSA normally requires overnight polysomnography. Cheyne-Stokes respiration is usually observed in patients with cardiac failure or stroke.

The management of CSA should be supervised by a pulmonologist, neurologist or sleep physician. The initial treatment of CSA should be directed at any casual or exacerbating factors.

Sleep-related Hypoventilation

Sleep-related hypoventilation is outlined by decreased alveolar ventilation, resulting in sleep-related oxygen desaturation and hypercapnia.

Risk factors and consequences

Sleep-related hypoventilation can be of an unknown cause or secondary to a medical condition (such as obesity, lower airway obstruction, pulmonary parenchymal or vascular pathology, lower airway obstruction, or neuromuscular or chest wall disorders). The secondary forms are much more common than the unknown origin forms.

Diagnosis and management

During overnight sleep test, sleep related hypoventilation is identified by sleep related oxygen desaturation and hypercapnia (abnormally elevated carbon dioxide (CO2) levels in the blood) in excess of the rise in PaCO2 (Partial Pressure of Carbon Dioxide in Arterial Blood) that occurs during sleep in normal subjects. It is more marked during REM sleep because of loss of muscle tone and impaired arousal mechanisms.

The management of sleep-related hypoventilation should be supervised by a pulmonologist or sleep physician. The initial treatment should be directed at any causal or exacerbating factors.

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