Sleep-related hypoventilation or hypoxemia disorders

Description

The primary feature of these disorders is insufficient sleep related ventilation, resulting in abnormally elevated arterial partial pressure of carbon dioxide (PaCO2) during sleep. Sleep-related hypoxemia is diagnosed when overnight monitoring reveals sustained (> 5 minutes) decline in oxygen saturation to ≤ 88% in adults (or ≤ 90% in children) for ≥ 5 minutes. Note: A definitive diagnosis requires objective evidence based on polysomnography as well as carbon dioxide (CO2) monitoring during sleep (by arterial, end-tidal or transcutaneous measures). [1]

Subcategories

• 7A42.0 Obesity hypoventilation syndrome

  Obesity hypoventilation syndrome is characterised by obesity (in adults, Body-Mass-Index > 30 kg/m²) and daytime hypercapnia indicated by arterial partial pressure of carbon dioxide (PaCO2) > 45 mm Hg that cannot be fully attributed to an underlying cardiopulmonary or neurologic disease. Hypercapnia worsens during sleep and is often associated with severe arterial oxygen desaturation. Obstructive sleep apnoea is also present in the majority of cases and should be diagnosed in addition to obesity hypoventilation. Note: A definitive diagnosis requires demonstration of daytime hypercapnia and objective evidence based on polysomnography, with carbon dioxide (CO2) monitoring (by arterial, end-tidal or transcutaneous measures). [1]

• 7A42.1 Congenital central alveolar sleep-related hypoventilation

  Congenital central alveolar hypoventilation syndrome (CCHS) is a disorder of autonomic dysfunction, primarily the failure of automatic central control of breathing, caused by a mutation of the PHOX2B gene. CCHS is characterised by hypoventilation, which is worse during sleep than wakefulness. Onset is usually at birth, and CCHS most commonly presents in an otherwise normal-appearing infant who is noted to have cyanosis, feeding difficulties, hypotonia or, less commonly, central apnoea. Severity is related to the specific mutation present. Individuals with milder variants of the disorder may not present for clinical attention until adulthood. Note: A definitive diagnosis requires demonstration of PHOX2B mutation and objective evidence based on polysomnography with carbon dioxide (CO2) monitoring (by arterial, end-tidal or transcutaneous measures). [1]

• 7A42.2 Non-congenital central hypoventilation with hypothalamic abnormalities

  Non-congenital central hypoventilation with hypothalamic dysfunction is a disorder of central control of ventilation. Patients are usually healthy until early childhood (often 2-3 years of age) when they develop hyperphagia and severe obesity, followed by central hypoventilation, which often presents as respiratory failure. Hypothalamic endocrine dysfunction may be characterised by increased or decreased hormone levels and may include one or more of the following: diabetes insipidus, inappropriate antidiuretic hormone hypersecretion, precocious puberty, hypogonadism, hyperprolactinemia, hypothyroidism, and decreased growth hormone secretion, or tumours of neural origin. Mood and behaviour abnormalities, sometimes severe, are often present. Developmental delay or autistic features may be present, but many patients are cognitively normal. Note: A definitive diagnosis requires objective evidence based on polysomnography with carbon dioxide (CO2) monitoring (by arterial, end-tidal or transcutaneous measures). [1]

• 7A42.3 Idiopathic central alveolar hypoventilation

  Idiopathic central alveolar hypoventilation is defined as the presence of decreased alveolar ventilation resulting in sleep related hypercapnia and hypoxemia in individuals with presumed normal mechanical properties of the lung and respiratory pump. Chronic hypoventilation during sleep exists without any readily identifiable impairments of respiration, such as pulmonary airway or parenchymal conditions, neurologic, neuromuscular or chest wall abnormalities, severe obesity, other sleep related breathing disorder, or use of respiratory depressant medications or substances. Diurnal as well as nocturnal hypoventilation is believed to be due primarily to blunted chemoresponsiveness to carbon dioxide (CO2) and oxygen (O2). Patients may complain of morning headaches, fatigue, neurocognitive decline and sleep disturbance, or may be entirely asymptomatic. Note: A definitive diagnosis requires objective evidence based on polysomnography with carbon dioxide (CO2) monitoring (by arterial, end-tidal or transcutaneous measures). [1]

• 7A42.4 Sleep-related hypoventilation due to a medication or substance

  Sleep-related hypoventilation due to a medication or substance is characterised primarily by chronic hypoventilation and hypercapnia due to prolonged use of medications or substances known to depress ventilatory drive and/or impair respiratory muscle mechanics (e.g. long-acting narcotics, anesthetics, sedative compounds, and muscle relaxants). Hypoxemia is commonly present as well. Hypercapnia may also be present during wakefulness in some patients. Patients can either be asymptomatic or present with complaints of dyspnea, chest tightness, or fatigue. Note: A definitive diagnosis requires objective evidence based on polysomnography with carbon dioxide (CO2) monitoring (by arterial, end-tidal or transcutaneous measures) in the context of medication or substance use that is judged to be causing the symptoms. [1]

• 7A42.5 Sleep-related hypoventilation due to medical condition

  Sleep-related hypoventilation due to medical condition is characterised by sleep-related hypoventilation due to lung airway or parenchymal disease, chest wall disorders, pulmonary hypertension, or neurologic and neuromuscular disorders. Daytime hypercapnia may also be present. Sleep related hypoxemia may be severe. Patients can either be asymptomatic or present with complaints of dyspnea, chest tightness, or fatigue. Note: A definitive diagnosis requires objective evidence based on polysomnography with carbon dioxide (CO2) monitoring (by arterial, end-tidal or transcutaneous measures) in the presence of a medical condition that is judged to be causing the symptoms. [1]

• 7A42.6 Sleep-related hypoxemia due to a medical condition

  Sleep related hypoxemia due to a medical condition is characterised by sustained declines in SpO2 (oxygen saturation measured by pulse oximeter) (≤ 88% in adults or ≤ 90% in children for ≥ 5 minutes) during sleep. The condition is attributable to a medical or neurological disorder. The presence of hypoxemia is not better explained by another sleep related breathing disorder (e.g., obstructive sleep apnoea). Although some amount of obstructive or central apnoea may be present, these disorders are not thought to be primarily responsible for the hypoxemia during sleep. Some patients with sleep related hypoxemia also exhibit hypoxemia during wakefulness. If the presence of hypercapnia has been established, a diagnosis of sleep-related hypoventilation should be made, rather than sleep-related hypoxemia. Note: A definitive diagnosis requires objective evidence based on polysomnographic monitoring of oxygen saturation in arterial blood (SaO2) in the presence of a medical condition that is judged to be causing the declines in SaO2. [1]

References

1. World Health Organization. International Classification of Diseases, 11th Revision, for Mortality and Morbidity Statistics (ICD-11 MMS), 2026-01 release. World Health Organization; 2026.

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