Central sleep apnoea

Overview

Central sleep apnoea (CSA) is a serious condition that is most commonly seen in patients with heart failure (heart failure is an inability of the heart to pump adequate blood and oxygen around the body, often caused by enlarged, stiffened and damaged heart chambers). 30-80% of patients with heart failure have central sleep apnoea (approximately 4% of the population).

In CSA, respiratory effort and breathing are periodically compromised due to a complex combination of changes in the cardiovascular system and breathing control centres.

The Difference between Central and Obstructive Sleep Apnoea

It is very important to distinguish between central sleep apnoea and obstructive sleep apnoea, although the two conditions can be present at the same time.

Obstructive sleep apnoea (OSA) is characterised by repetitive episodes of obstructed breathing, usually due to a narrow, collapsible airway. In patients with OSA, the thoracic (chest) and abdominal (diaphragm) muscles still continue their efforts move air into and out of the lungs, despite the airway being obstructed. Oxygen and carbon dioxide levels in the blood stream reach dangerous levels if the airway comes obstructed for too long. The brain senses this and intervenes, stimulating the body to take deeper breaths and overcome the obstruction. Breathing then resumes again, but at the expense of disrupted sleep.

Central sleep apnoea is characterised by repetitive episodes of shallow or absent breathing, resulting from temporary loss of ventilatory effort. That is, breathing ceases because the thoracic and abdominal muscles lose their instruction from the brain to continue moving air to and from the lungs. Breathing usually commences again in time, once the blood oxygen and carbon dioxide levels change enough to stimulate breathing again, but this is often associated with arousal from sleep, leading to difficulties in sustaining sleep and daytime tiredness. Central sleep apnoea may occur in the absence or presence of obstructive sleep apnoea.

Signs and symptoms

Patients with central sleep apnoea often present with:

  • Daytime tiredness and fatigue
  • Waking unrefreshed, even after sleeping for many hours
  • Episodes where breathing appears gradually to wax and wane
  • Lack of energy and drive
  • Falling asleep during the day or a need for frequent naps
  • Symptoms of heart failure.

If you have been diagnosed with a heart problem (especially heart failure), discuss having an overnight sleep study with your treating medical practitioner to check for both central and obstructive sleep apnoea.

Causes of Central Sleep Apnoea

The causes of central sleep apnoea are complex, involving the cardiovascular system (heart), the pulmonary system (lungs) and the autonomic nervous system (brain and nerves).

The precise cause of central sleep apnoea is not yet completely understood. Several factors are thought to contribute to central sleep apnoea, including:

  • Impairment of the function of respiratory control centers in the brain
  • Impairment of the heart’s functional capacity to pump oxygenated blood around the body
  • Delayed cardiovascular information transfer times, caused by heart failure
  • Changes in blood chemical and gas concentrations
  • Changes in hormone and protein levels
  • Sleeping in a supine (compared with a lateral) position.

Diagnosis

Central sleep apnoea is diagnosed with a full (“Level 1”) overnight diagnostic sleep study or polysomnogram (PSG). Amongst other things, this type of PSG closely monitors brain waves, breathing, respiratory drive and oxygen levels to determine both if breathing ceases, and the severity of the problem.

Treatment

The treatment of central sleep apnoea is individualised, depending on the cause of the breathing instability – if the condition is secondary to a heart problem, the heart problem needs to be investigated and treated first. When obstructive sleep apnoea is also present, CPAP therapy may be introduced. There are also new types of CPAP machines which are designed to monitor breathing continuously and reduce the severity of abnormal breathing. The most appropriate device will be determined by one of our experienced Sleep Specialists.