Sleep and Sleep disordered breathing in Cystic Fibrosis
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Chronic respiratory disease such as cystic fibrosis can be associated with sleep disturbance due to problems such as cough, wheeze, nasal obstruction or side effects of medication. In addition, due to limited pulmonary reserve, the normal physiological changes in sleep can cause significant gas exchange abnormalities leading to sleep fragmentation and adverse effects on daytime function. This is especially so in those with advanced lung disease, but can occur in those with stable lung disease. A study of children with cystic fibrosis between the ages of 6 months and five years reported 32% had mild to moderate sleep related behavioural problems, and in 22% the problems were more troublesome3.
Common sleep complaints in cystic fibrosis include :
- sleep onset insomnia
- frequent awakening
- nocturnal cough
- daytime somnolence
- frequent defaecation
Poor quality sleep is often multifactorial in children with cystic fibrosis.
Sleep may be disrupted by:
- nasal obstruction eg rhinosinusitis, polyps
- nocturnal cough and other respiratory symptoms
- musculoskeletal or abdominal pain
- frequent bathroom use for defaecation
- use of medications that may disrupt sleep eg b-2 agonists, theophyllines, corticosteroids
- diagnosis-related chronic anxiety
- poor sleep hygiene
Regardless of the severity of lung disease, all children with cystic fibrosis should be asked about sleep problems at outpatient review. This includes snoring but also hypoventilation (eg morning headaches, awakenings, tiredness). While sleep-disordered breathing is seen in adolescents and young adults with more advanced lung disease, there is only a weak correlation between the extent of desaturation during sleep and daytime oxygenation or pulmonary function. Progressive deterioration of lung function in cystic fibrosis may lead to significant hypoxaemia and hypercapnia. Subclinical pulmonary hypertension develops in a significant proportion of patients and is strongly correlated with hypoxaemia, independent of pulmonary function.
Respiratory support in cystic fibrosis
The indication for respiratory support during sleep in cystic fibrosis is not precisely defined. Respiratory support can be supplemental oxygen therapy, non-invasive ventilation (NIV), or both modalities in combination. While the decision to initiate home oxygen therapy is commonplace for many children with chronic lung disease, the decision to commence a child with cystic fibrosis on NIV requires more specialised clinical judgement, and should be made in conjunction with a Paediatric Sleep Medicine Specialist.
Nocturnal hypoxaemia in cystic fibrosis has been demonstrated for decades especially during acute respiratory exacerbations. Desaturation is often most pronounced during REM sleep due to a combination of ventilation/perfusion imbalance and hypoventilation. Oxygen therapy may be indicated for nocturnal hypoxaemia, and may improve cognitive function and schooling in young adults. Hypoxaemia (nocturnal or diurnal) may only be manifest during acute respiratory exacerbations. All children admitted for an acute exacerbation should have continuous overnight oximetry performed as soon as possible when in hospital. Oximetry should be performed in accordance with the current Starship Clinical Guidelines for oximetry.
Oxygen at home may be considered when the oxygen saturation is below 90% for more than 10% of the night, in a clinically stable period. Significant CO2 retention is unlikely in hypoxic children who are normocapnic during the day. With more advanced lung disease, marked nocturnal hypoventilation with high CO2 levels can be seen. Carrying out carbon dioxide monitoring (eg early morning capillary gas CO2 or if available, transcutaneous CO2 measurement) in conjunction with oximetry is recommended if oxygen therapy is to be considered.
All the studies in the Cochrane review on oxygen therapy7 compared low-flow oxygen to room air. There is no evidence to date regarding the utility of high flow nasal cannulae oxygen in children with either acute or advanced disease.
Non-invasive ventilation (NIV)
NIV may be indicated for a variety of reasons in cystic fibrosis. Children who have symptoms of sleep disordered breathing or sleep-related hypoventilation should be referred to centres with expertise in paediatric sleep medicine for consideration of a polysomnogram (PSG), especially if NIV is to be considered. Sleep disordered breathing may be of sufficient severity to necessitate use of respiratory support eg continuous positive airway pressure (CPAP) or NIV. There is evidence that NIV can unload respiratory muscles, and so improve alveolar ventilation and gas exchange.
While there are no empiric data to verify, suggested theoretical benefits for use of NIV in cystic fibrosis include :
- acceleration of recovery during an acute exacerbation
- improvement of quality of life
- improvement of nutritional status
- improvement of respiratory muscle performance
- stabilisation of lung function decline
- increased survival
When children with cystic fibrosis have advanced lung disease with high CO2 levels (hypercapnic respiratory failure,) NIV may improve sleep quality and health status which may be advantageous as a bridge for those awaiting transplantation, or can be used to enable optimal oxygenation without worsening CO2 levels, as well as achieve a reduction in associated symptoms and hence improve quality of life. Other studies have shown that in moderate to severe cystic fibrosis lung disease when NIV is used in addition to oxygen, this may improve gas exchange during sleep to a greater extent than oxygen therapy alone. These benefits of NIV have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remains unclear.
In summary, while NIV may be a useful adjunct to other airway clearance techniques for some patients with severe disease, to date there is no definitive evidence regarding the efficacy, safety and acceptability of NIV in CF.
- New Zealand Guidelines for the Assessment of Sleep Disordered Breathing in Childhood. Paediatric Sleep Medicine Clinical Network, New Zealand Child and Youth Clinical Networks.
- Elliot S Katz Cystic Fibrosis and Sleep Clin Chest Med 2014; 35: 495-504.
- Ward C et al. Arch Dis Child. 2009;94:341.
- Amin R et al. Chest. 2005;128:1357
- Faroux B, Khirani S. In Bush A, Bilton D, Hodson M (Eds). Hodson and Geddes' Cystic Fibrosis, Fourth edition. Boca Raton, FL. CRC Press. 2016.
- Elphick HE, Mallory G. (2013) Oxygen therapy for cystic fibrosis. Cochrane Database of Systematic Reviews Issue 7 DOI: 10.1002/14651858.CD003884.pub4
Document last reviewed April 2017
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