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Obstructive sleep apnoea:a cause for concern

Carol Beckwith
RN DPNS BSc(Hons)
Nurse Specialist
Regional Sleep Service Wythenshawe Hospital
South Manchester University
Hospital Trust
Manchester
E:carol.beckwith@smuht.nwest.nhs.uk

Up to 40% of the adult population snore.(1) For some, snoring is so troublesome to them or their bed partners that they seek medical advice from their GP. Of these, more than one-third may have clinically significant sleep-disordered breathing. Simple screening at this stage, using the Epworth Sleepiness Scale (ESS), is a quick and validated method of assessing whether or not a patient is sleepy (see Table 1).(2) An ESS score can be used to clinically subdivide patients - normal ESS is 11 or less.(2) The score, together with body mass index (BMI) and measure of neck circumference, may be a sufficient assessment along with a detailed history before considering referral on to a specialist centre.

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Simple snoring without sleep-disordered breathing can be treated initially with weight loss and alcohol avoidance.(3) Changing sleep position to avoid sleeping on the back is also helpful in some cases. In normal-weight patients, fitting of an orthodontic appliance (anterior mandibular device), which repositions the lower jaw forward by a gum shield worn during sleep, can be considered. These are sometimes available within the NHS or can be purchased independently, fitted by orthodontists and some dentists. A referral to an ENT specialist may also be helpful to some patients.

What is obstructive sleep apnoea?

The most common treatable medical cause of excessive daytime sleepiness is obstructive sleep apnoea (OSA).(4) Four per cent of middle-aged men and 2% of middle-aged women are estimated to suffer from OSA.(5) An increase in obesity, together with earlier recognition of symptoms, and patient and GP awareness are some of the reasons why the demand for treatment of sleep disorders has risen in the UK. It is, however, estimated that 80% of patients with OSA remain undiagnosed and untreated.(6)
OSA is an intermittent collapse of the upper airway that occurs repeatedly during sleep. This collapse can be complete, with total obstruction of the airway, no respiratory airflow and oxygen desaturation.
An apnoea is defined in adults as a 10-second breathing pause when the patient is asleep and the muscle tone in the upper airway decreases. This disrupts airflow, leads to a decrease in oxygen within the blood and prompts an increase in respiratory effort in an attempt to overcome it. This leads to a transient arousal from deep sleep. This type of sleep fragmentation repeats throughout the night, and the patient awakes feeling unrefreshed; in turn this produces the symptoms of excessive daytime sleepiness, fatigue, poor concentration and a reduction in alertness. Because of restlessness and a disturbed sleep pattern the quality of the patient's sleep is poor. OSA may lead to nocturia and impotence, and patients are more likely to be irritable during the day.

Factors for sleep apnoea
In adults, the most common contributory factor is obesity. Fat is laid down in the neck in a greater extent in men than in premenopausal women, but individual variations in skeletal and soft tissue morphology may also determine those patients who are more likely to develop OSA. Patients with OSA often have a neck circumference of over 43cm. Micrognathia, retrognathia, large tonsils, acromegaly and some neuro-muscular conditions, such as previous poliomyelitis or motor neurone disease that weaken the dilator muscles in the pharynx, can lead to OSA. Other factors to consider in assessing the patient with excessive daytime sleepiness are shiftwork, poor sleep habits, alcohol and caffeine consumption, diabetes, hypothyroidism and drug therapies such as sedatives, ß-blockers and antidepressants.
The most serious potential consequences of untreated OSA are traffic accidents and accidents in the workplace.(7,8) Because of this, health professionals are responsible for advising those patients with excessive daytime sleepiness to refrain from driving until they have been successfully treated. Patients are required to inform the DVLA in Swansea following a diagnosis of OSA. Failure to do so may invalidate their insurance cover, and in the majority of cases the DVLA is happy to allow drivers to continue driving once they have been successfully treated.
There has been recent evidence that patients with OSA have an increased risk of high blood pressure and a greater risk of cardiovascular problems.(9,10)

Treatment
Treatment in its simplest form is to lose weight. As well as having an impact on OSA, in health terms, losing weight will also have a positive affect on hypertension and diabetes and reduce any cardiovascular risk.(5)
However, the evidence supports the treatment of choice for OSA as the use of nasal continuous positive airways pressure, or nasal CPAP.(11) CPAP is a gentle flow of pressurised air delivered via the nose or mouth by a soft silicone mask worn on the face when the patient is asleep.(11) This keeps the airway open, stops the throat from narrowing and prevents apnoea, oxygen desaturation and snoring. Long-term treatment and compliance with this type of treatment provides relief from excessive daytime sleepiness and other symptoms and good-quality sleep.(12) The treatment has been proven to be cost-effective and to improve the individual's quality of life.(13)
Establishing and initiating CPAP should be undertaken only after expert clinical evaluation at specialist centres that have a multidisciplinary approach to the treatment of sleep apnoea. The expertise within such units and centres will ensure that the patient receives rigorous assessment, the best advice and thorough explanation of the treatment options that are applicable to their level of symptoms.

The future of OSA in the UK
Service provision to patients varies tremendously across the UK. Most centres now find that they are underfunded by PCTs and severely restricted in service development, resources and expansion. The British Thoracic Society (BTS) intervened in 2004 to look at the inequity of services and to coordinate pressure on the Department of Health for further resources and funding for the treatment of sleep apnoea. From this the BTS Sleep Apnoea Consortium was convened. The group meets three to four times a year and consists of experts in the field of sleep apnoea - physicians, clinical scientists, respiratory nurse specialists, physiotherapists, patient group and industry representatives. I was asked to join as a nurse representative, and this has given me a great insight into the issues that surround sleep apnoea services, and the effect that this has on patient care.
The aim of the group is to raise the issues of underfunding and what amounts to "postcode" prescribing of treatment for sleep apnoea. The main focus now is  getting the National Institute for Health and Clinical Excellence (NICE) to accept the extensive and overwhelming amount of clinical evidence on OSA and produce substantive guidelines. This would give every centre recognition and reimbursement for services that allow patients equity and access to service provision.
Education and standards of care delivery have also been explored, and a group of experts are coordinating a "toolkit" of information that will soon be available on the BTS website. This is intended to be a cornerstone of good practice and useful to those staff working with sleep apnoea. This means that throughout the UK knowledge and skills will be updated and shared to generate up-to-date developments in the treatment of OSA by disseminating and sharing good practice.

Conclusion
Obstructive sleep apnoea can no longer be regarded as unimportant. Those of us who see the positive effect that nasal CPAP treatment has know only too well that it is a cost-effective treatment with an outcome that transforms each patient's life.

References

  1. Partridge M. Obstructive sleep apnoea syndrome. Airways J 2003;1(3):117-18.
  2. Johns MW. A new method of measuring daytime sleepiness; the Epworth Sleepiness scale. Sleep 1991;14:540-5.
  3. Stone P. When snoring requires serious attention. The Practitioner 1998;242:460-4.
  4. Stradling JR, Davies RJO. Sleep 1: Obstructive sleep apnoea/hypopnoea syndrome: definitions, epidemiology, and natural history. Thorax 2004;59:738.
  5. Scottish Intercollegiate Guideline Network. Management of obstructive sleep apnoea/hypopnoea syndrome in adults. SIGN Guideline no. 73. Edinburgh: SIGN; 2003. Available from http://www.sign.ac.uk
  6. Schneerson J. Sleep apnoeas. Primary Care Respiratory J 2002;1(4):114-16.
  7. George CF. Sleep apnoea and automobile crashes. Sleep 1999;22:790-5.
  8. George CF. Reduction in motor-vehicle collisions following treatment of sleep apnoea with nasal CPAP. Thorax 2001;56:508-12.
  9. Robinson GV, Stradling JR, Davies RJO. Sleep 6: Obstructive sleep apnoea/hypopnoea syndrome and hypertension. Thorax 2004;59:1089-94.
  10. Peppard PE, Young T, Palta M, Skatrud J. Prospective study of the association between sleep disordered breathing and hypertension. N Engl J Med 2000;342:1378-84.
  11. Wright J, White J, Ducharme F. Continuous positive airways pressure for obstructive sleep apnoea. (Cochrane review). In: Cochrane Library. Issue 2. Oxford: Update Software; 2002.
  12. Jenkinson C, Davies RJ, Mullins R, Stradling JR. Comparison of therapeutic and sub-therapeutic nasal continuous positive airways pressure for obstructive sleep apnoea: a randomised prospective parallel trial. Lancet 1999;353:2100-5.
  13. Douglas NG, George CF. Treating sleep apnoea is cost effective. Thorax 2002;57:93.

Resources
Association of Respiratory Nurse Specialists 
W:www.arns.co.uk
British Sleep Society
W:www.britishsnoring.co.uk
British Thoracic Society
W:www.brit-thoracic.org.uk
Sleep Apnoea Trust
W:www.sleep-apnoea-trust.org