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A guide to the effective treatment of sleep apnoea

Rebecca Mullins
Clinical Nurse Specialist

Obstructive sleep apnoea (OSA) is a common but under-recognised condition. Rebecca Mullins explains how primary care nurses can be more alert to its signs and symptoms.

Obstructive sleep apnoea (OSA) is a common but under-recognised condition and we need to be more alert to its signs and symptoms. It is characterised by partial or total collapse of the upper airway during sleep, signalled by loud snoring and by apnoeas that result in hypoxaemia with sleep fragmentation, daytime sleepiness and diminished quality of life.

It can be caused by excessive fatty tissue around the neck - often associated with obesity - and by pharyngeal narrowing, craniofacial abnormalities, smoking, alcohol and sedative use.

The burden of OSA
OSA, also referred to as obstructive sleep apnoea/hypopnoea syndrome (OSAHS), is an important risk factor for cardiovascular disease (CVD) and hypertension; is associated with type 2 diabetes; and negatively impacts quality of life. In fact, many studies indicate that if the condition is left untreated, sufferers are at increased risk of hypertension, CVD, stroke, motor vehicle accidents and diminished quality of life.1-5

OSA is thought to be as prevalent as type 1 diabetes and approximately twice as common as severe asthma.6 Epidemiological studies have shown a high prevalence and severity of undiagnosed OSA, affecting 2-4% of adult men and about 1% of adult women globally.7 For these reasons, it is extremely important to assess these patients correctly and refer them for appropriate evaluation and treatment as necessary.

Left untreated, OSA has a far-reaching impact on the affected person and their partner's quality of life, due to sleep fragmentation and resulting excessive daytime sleepiness. This can impair concentration levels, leading to irritability, depression and poor work performance. As a result, patients are often treated for symptoms, such as depression and weight loss, rather than for OSA itself.

There are a number of common indicators of OSA:

  • Snoring.
  • Excessive daytime sleepiness.
  • Impaired concentration.
  • Obesity (BMI >30).
  • Collar size >17 inches.
  • Unrefreshing sleep.
  • Nocturnal choking.
  • Witnessed apnoeas.
  • Nocturia.
  • Morning headaches.

Any person who exhibits one or more of these may be at risk of OSA and should be considered for further screening. High numbers of patients are not identified as being at risk of OSA and hence are not treated.

In March 2008, the National Institute for Health and Clinical Excellence (NICE) released a Health Technology Appraisal (HTA) for the treatment of OSAHS and advised that CPAP (continuous positive airway pressure) treatment be made available to all moderate-to-severe OSA patients, along with the necessary funding. But first, the symptoms must be recognised by the GP.

Unfortunately, since the release of the NICE HTA there has not been a significant increase in referrals and this may be due to lack of training, not only on sleep apnoea in particular but also on sleep conditions in general. A study by Stores and Crawford (1998), published in the Journal of the Royal College of Physicians of London, found that undergraduates receive five minutes of sleep training, preclinical students receive 15 minutes and clinical students receive none, with limited focus on sleep disorders. As a result, this condition often goes unrecognised or misdiagnosed.

From March 2009, primary care trusts (PCTs) were required to implement the NICE guidelines and ensure a sleep service is available; but many GPs are not aware they exist and send these patients to ENT for potential tonsillectomies, and this is not the solution for OSA patients. Additionally, patients who have such surgery and later go on to obtain CPAP treatment then find it much harder to tolerate due to the surgery. Diagnosis of OSA is straightforward, and treatment is simple and cost-effective as demonstrated in the HTA.

Diagnosis and treatment
The Epworth Sleepiness Score (ESS) is a questionnaire that can be used to measure a patient's perception of sleepiness.6 It uses eight questions, each scored 0-3, to quantify the likelihood of falling asleep during daily activities. Total scores of greater than 10 indicate abnormal daytime sleepiness.

The score can be used to clinically subdivide patients into the normal range (ESS 18). The score should be completed independently by both the patient and their partner, as the patient may underestimate the severity of their sleepiness due to its insidious onset or to hide concerns over their driving ability.

Although the correlation between ESS and OSAHS severity is relatively weak, the ESS is the best available tool to guide the clinician as to the patient's perception of their sleepiness.6 Patients can also be screened using a technological device that incorporates a nasal cannula. The device is validated to measure nasal air flow and can be worn by patients at home overnight and can also include oximetry. The results indicate a person's risk of having OSA. Such tools are now commonly being used to carry out a diagnosis.

Following a positive finding for OSA, the options of NHS or a private sleep centre can be discussed and a referral made for an overnight sleep study to offer a definitive diagnosis. In some cases, this can also be carried out at home.
Once OSA has been diagnosed, treatment using CPAP is simple and successful. The CPAP device is worn at night, and gently blows air through the upper airway to prevent collapse, which, in turn, reduces sleep fragmentation. CPAP delivers pressurised air via a nasal or oronasal mask from a small device by the bedside.

Once patients are referred to their local sleep service they should be diagnosed and treated quickly and effectively by a team of trained and experienced sleep professionals. For example, experienced clinicians should provide individuals with comprehensive OSA screening, testing, treatment and aftercare, following guidelines for standards of care issued by the British Thoracic Society (BTS) and Association for Respiratory Technology and Physiology (ARTP) professional bodies.

Other treatments for OSA include lifestyle changes, such as weight loss (in milder cases), oral appliances and surgery. However, CPAP remains the gold standard for treatment in most moderate-to-severe OSA.

References
1. Pepperell JC, Ramdassingh-Dow S, Crosthwaite N et al. Ambulatory blood pressure after therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnoea: a randomised parallel trial. Lancet 2002;359:204-10.
2. Roux F, D'Ambrosio C, Mohsenin V. Sleep-related breathing disorders and cardiovascular disease. Am J Med 2000;108:396-402.
3. Dyken ME, Somers VK, Yamada T, Ren ZY, Zimmerman MB. Investigating the relationship between stroke and obstructive sleep apnea. Stroke 1996;27:
401-7.
4. Findley LJ, Suratt PM. Serious motor vehicle crashes: the cost of untreated sleep apnoea. Thorax 2001;56:505.
5. Jenkinson C, Stradling J, Petersen S. Comparison of three measures of quality of life outcome in the evaluation of continuous positive airways pressure therapy for sleep apnoea. J Sleep Res 1997;6:199-204.
6. Scottish Intercollegiate Guidelines Network (SIGN). Management of Obstructive Sleep Apnoea/Hypopnoea Syndrome in Adults. Edinburgh: SIGN; 2003.
7. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;328:1230-5.

Resources
Sleep Apnoea Trust
W: www.sleep-apnoea-trust.org

ResMed (information for patients)
W: www.osauk.org
0800 917 7091

ResMed (information for clinicians)
W: www.resmed.com
0800 917 7091

GP information
W: www.Doctors.net.uk