Great Ormond Street Hospital for Children NHS Foundation Trust: Information for Families

Sleep related hypoventilation (SRH)

This information sheet from Great Ormond Street Hospital (GOSH) explains the causes, symptoms and treatment of sleep related hypoventilation (SRH) and where to get help.

What is sleep related What causes sleep related hypoventilation? hypoventilation? Hypoventilation describes the state in which a SRH can occur as a part of various conditions: reduced amount of air enters the alveoli in the 1. where the main breathing muscles and in lungs, resulting in low blood levels of oxygen particular the diaphragm, are affected (for

(O2) and increased levels of the body’s waste example Neurological, Neuromuscular or

gas, carbon dioxide (CO2). Hypoventilation Obesity Hypoventilation syndromes) can be due to breathing that is too shallow, 2. where narrowed airways are prominent breathing that is too slow, obstructed airways (for example, in Obstructive Sleep Apnoea or restricted or damaged lungs. (OSA)) When children sleep, the stages of sleep 3. where the lung is damaged can be divided into either REM (rapid-eye 4. where the lung is restricted from moving movement sleep or dream sleep) or NREM (for example, with chest wall deformities) (non rapid-eye movement sleep). The muscles that help the body to breathe and keep the 5. where the brain’s control of breathing air passages open work fully in NREM sleep. is impaired (for example, in Congenital In REM sleep, however, these muscles relax Central Hypoventilation Syndrome (CCHS)) leading to shallower breathing. For this reason REM sleep is often the period when sleep- What are the signs and related hypoventilation occurs in children and young people with other underlying symptoms of sleep related medical problems. If the underlying disorder hypoventilation? deteriorates or worsens, then there may Signs and symptoms of SRH are related be further respiratory weakness, with to the higher levels of carbon dioxide hypoventilation developing in all sleep stages in the blood and to sleep disturbance. and even during the day. They include: morning headaches, restless sleep, daytime tiredness or sleepiness and difficulty concentrating at school. Recurrent respiratory problems can also be present including chest infections such as bronchitis, and shortness of breath. Although these signs and symptoms are common, they may not be recognised as signs of SRH.

Sheet 1 of 2 Ref: 2016F1852 © GOSH NHS Foundation Trust February 2017 How is sleep related at pressure to help the respiratory muscles, hypoventilation diagnosed? improve lung inflation and oxygen levels, as well as helping to remove CO2 during sleep. Several investigations may be needed to This treatment is not a cure for SRH as this is diagnose SRH. The daytime diagnostic often related to an underlying condition. tests which may be performed include: Scoliosis is often seen in children with lung function tests (blowing tests such as neuromuscular and neurological conditions. spirometry and peak cough flow), assessment As the curvature of the spine increases, the of respiratory muscle strength, measurement inflation of the lungs is restricted and this of daytime oxygen levels (oxygen saturations may increase SRH. This is not easily reversed, or SpO ) and capillary blood gas (a blood test 2 despite surgical correction but sometimes to measure the CO level in the blood). These 2 there will be a mild improvement of the daytime tests may suggest that your child has underlying SRH. SRH and if this is the case, a sleep study will need to be conducted. A sleep study usually means an overnight stay What happens next? in a sleep unit, where measurements of the If your child has been diagnosed with SRH child’s breathing during sleep are recorded and has been treated or if it was decided by technologists/physiologists experienced to wait and follow progress, a follow-up in working with children. The measurements sleep study will be arranged. This enables are recorded using stick-on or wrap-around the medical professionals to assess if the sensors and include respiratory rate, heart SRH has been successfully managed or if an rate, oxygen saturation, chest wall movement, alternative therapy is required. Treatment of

airflow, measurement of CO2, video and sound SRH in children and young people has been recording. The results are then interpreted by shown to improve quality of life, daytime a paediatric sleep consultant, who can make a function including learning, concentration diagnosis of SRH. and attention. There may also be less daytime fatigue, improvement in sleep quality, and How is sleep related fewer chest infections. hypoventilation treated? The decision to start treatment is made Further information on a case-by-case basis once SRH has been and support confirmed and will depend on the underlying The British Lung Foundation offers support reason for SRH. and advice to anyone affected by a breathing Positive Airway Pressure therapy (often in condition. Call their helpline on 03000 030 555 the form of BPAP = Bilevel Positive Airway from Monday to Friday from 9am to 5pm or Pressure, also known as non-invasive visit their website at www.blf.org.uk ventilation or NIV) is the usual treatment for The Sleep Apnoea Trust website SRH. This involves your child wearing a mask (www.sleep-apnoea-trust.org) contains over the nose and/or mouth while a positive information about all types of sleep apnoea. pressure is applied from a bedside device called a ventilator. This blows air into the lungs

Compiled by the Respiratory Medicine team in collaboration with the Child and Family Information Group Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London WC1N 3JH www.gosh.nhs.uk

Sheet 2 of 2 Ref: 2016F1852 © GOSH NHS Foundation Trust February 2017