VOL: 101, ISSUE: 23, PAGE NO: 34
Alison Malcolm, RN, BSc, is staff nurse, Royal Infirmary of Edinburgh
Obstructive sleep apnoea/hypopnoea syndrome affects around two per cent of middle-aged men and one per cent of middle-aged women (30-65 years), although the condition is thought to be under-reported. Thus its prevalence is likely to be similar to that of type 1 diabetes (SIGN, 2003).
Apnoea is defined as a 10-second breathing pause and hypopnoea as a 10-second event where there is continued breathing but ventilation is reduced by at least 50 per cent from the previous baseline during sleep (SIGN, 2003). Obstructive sleep apnoea causes excessive daytime sleepiness that interferes with cognitive function and the ability to cope with everyday life. In particular it affects driving ability - the latest UK accident figures suggest that around 20 per cent of major highway accidents are caused by drivers falling asleep at the wheel, a proportion of which are the result of sleep apnoea (SIGN, 2003).
People with the condition are obliged to inform the DVLA and to stop driving until treatment is successful. A University of Edinburgh study stated that, ‘the problem should be treated at least as seriously as drink driving and must therefore try to raise public awareness to the same level. Sleep apnoea can be effectively treated almost overnight - and the results of this project could go a long way to making our roads safer’ (Newby, 2004).
Daytime sleepiness is also a factor in accidents at work (SIGN, 2003) and affects relationships between people with the condition and their partners if both experience disturbed sleep.
The Sleep Apnoea Act 2004 aims to empower the National Institute for Clinical Excellence to draw up guidelines for the management of sleep apnoea within 12 months of the act coming into force. Primary care trusts in England will then have 12 months to implement the guidelines. Guidelines are already in place in Scotland, where over 2,500 people are receiving treatment for sleep apnoea and this figure is likely to increase (SIGN, 2003).
Obstructive sleep apnoea/hypopnoea
What happens during sleep
During deep sleep the muscles of the throat relax along with many other muscle groups. This relaxation causes the upper respiratory passage to narrow. Normally this does not cause any problems, but for some, especially those in middle age and those who are overweight, it may result in snoring. While this may be irritating for partners, it does not affect their health or ability to cope with daily life. Snoring can be reduced by avoiding sleeping on the back, losing weight, or in more severe cases using dental devices that pull the lower jaw forward and prevent the tongue and throat muscles from obstructing the respiratory passage.
However, for some people the muscle relaxation causes complete obstruction or severe restriction of the airway, leading to apnoea or hypopnoea (Fig 1). Blood oxygen levels start to fall and after 20-60 seconds of failed or restricted inspiratory effort the brain is alerted and the person wakes or moves into a lighter sleep phase, muscle tone is restored and breathing returns to normal. Fig 2 shows the cycle of events that repeat throughout deep sleep, sometimes hundreds of times a night. This disrupts the normal sleep pattern, which should progress through light sleep to a deeper, slow-wave, restorative sleep. The broken pattern results in unsatisfactory rest and daytime symptoms of excessive sleepiness.
The condition is diagnosed thorough a clinical examination and history. The involvement of a spouse or partner can be helpful as those with the condition are often unaware of the extent of the problem, since it occurs during sleep. A witness can describe the episodes and estimate their frequency. Examination should include measurement of height, weight and neck circumference and assessment of the size and shape of the jaw. There is an increased incidence of the condition where the neck is wider than 17in.
Patency of the nasal cavity, any obstructions and how the person breathes through the nose are also important. The mouth and throat should be examined for problems with tongue, teeth or tonsils and blood pressure taken. Completion of an Epworth Sleepiness Scale questionnaire by both the person with the condition and their partner will give an objective indication of the severity of the problem and a means of measuring the effectiveness of subsequent treatment (SIGN, 2003).
The Epworth Sleepiness Scale is a simple, self-administered questionnaire developed to measure the general level of sleepiness by the likelihood of falling asleep in eight common situations. The score for each question ranges from 0 (not likely to fall asleep) to 3 (highly likely to fall asleep). The scores distinguish normal subjects, including those who simply snore, from people with obstructive sleep apnoea, narcolepsy and other sleep disorders (Epworth, 1991).
If necessary the patient can be referred to a sleep centre for limited sleep study, which typically involves an overnight stay for observation. Oximetry, in which oxygen levels are recorded and examined, can be helpful where other diagnostic tools have proved inconclusive, but further measures are rarely needed. A four per cent reduction in SaO2 at a rate of more than 10 per hour is indicative of obstructive sleep apnoea/hypopnoea syndrome (SIGN, 2003).
The severity of the condition is measured by the Apnoea/Hypopnoea Index (AHI) or Respiratory Disturbance Index (RDI), which records the number of typical episodes experienced each hour. Three degrees of severity are normally identified:
- Mild (5-14 per hour);
- Moderate (15-30 per hour);
- Severe (30 per hour).
The moderate and severe degrees of the condition are clinically significant.
In studies of patients with obstructive sleep apnoea syndrome ESS scores correspond well with the AHI and oximetry tests measuring minimum SaO2 levels (SIGN, 2003).
Before a diagnosis of obstructive sleep apnoea/hypopnoea syndrome is made, an examination should exclude other possible causes of sleepiness and snoring. These include pathology of the upper respiratory tract, depression, narcolepsy, hypothyroidism, periodic limb movement disorder, drugs (both sedatives and stimulants), excess alcohol and neurological conditions such as a previous head injury or Parkinson’s disease.
The main features of obstructive sleep apnoea/hypopnoea syndrome are excessive daytime sleepiness, impaired concentration and snoring. People with sleep apnoea are also likely to have raised blood pressure, possibly due to common factors, such as obesity, age, gender, smoking and alcohol consumption. Other symptoms include choking episodes during sleep, restlessness at night, irritability, nocturia and decreased libido. These can lead to relationship difficulties.
Lifestyle change is an integral part of the treatment of sleep apnoea. Smoking cessation, weight loss, reduced alcohol intake (especially at night) and decreased use of sedatives will all help with both the condition itself and with general health and well being (SIGN, 2003). However, such changes are not always easy to make, especially if the person is under stress, while trying to achieve too many goals at the same time can be counterproductive. For example, it is common for people to put on weight when trying to stop smoking and this may exacerbate the condition.
While lifestyle changes can improve the condition, the most effective treatment is the use of a continuous positive airway pressure (CPAP) device overnight at home (SIGN, 2003). The device delivers air via a mask or nasal cannula, supporting the palate and inhibiting the collapse that leads to apnoeic episodes. Thus the obstructive sleep apnoea cycle (Fig 2) fails to establish itself and a more normal sleep pattern ensues. This leads to a reduction in daytime sleepiness and improved cognitive function and quality of life measures - both objective (ESS and AHI scores) and subjective (how the sufferer reports any changes).
In the largest randomised controlled trial to date the use of CPAP resulted in a reduction in average ESS scores from 15.5 to 7, compared with a reduction from 15 to 13 in those receiving sham CPAP (Chilcott, 2000). The study concluded that the cost of CPAP treatment was in line with other routinely funded NHS treatments. The use of CPAP devices was also found to reduce hypertension.
In severe cases treatment can also reduce blood pressure and decrease cardiac risk. However, there are problems with this form of treatment in that compliance with the CPAP device may be difficult, especially as it must continue long term, possibly for life (SIGN, 2003).
Sleep apnoea is largely dealt with in primary care, with people with the condition approaching their GP for advice and treatment. However, nurses in the community may become involved if they detect problems during domicilary visits or surgery appointments, where patients may mention unusual sleepiness in themselves or their partners.
Questions about sleep patterns can also be asked at check-up appointments or during lifestyle discussions. Excessive daytime sleepiness with associated relationship problems or reduced motivation will almost certainly affect the way people act and approach other factors in their lives and nurses need to be sensitive to this.
Hospital nurses have a unique opportunity to observe patients sleeping, particularly at night, though clues may be discernible during the day. Any unusual patterns of waking or snoring should be explored with the patient to establish if there might be an underlying problem. Sleep patterns should be explored on admission and during any subsequent discussion on lifestyle (Kron, 1987).
A nurse’s understanding of the condition, its diagnosis and treatment may help patients to manage it while in hospital. For example, they may be reluctant to bring CPAP equipment to hospital, thinking it might disturb other patients or that there will not be room for it by the bed.
The nurse role in the use of the CPAP device will differ from that in its use in acute respiratory settings. Here the emphasis is on ensuring the patient can manage the device at home. This would include an explanation and demonstration of how the device works and how to prevent potential problems such as chafing from the mask or nasal cannula, particularly around the nose and ears or conjunctivital oedema. Dehydration or nausea can also cause problems (Mallett and Dougherty, 2000).
Key areas on which to focus in the manage- ment of people with obstructive sleep apnoea/hypopnoea syndrome include:
- Asking appropriate questions;
- Observing sleep patterns;
- Advising on lifestyle choices;
- Explaining and demonstrating;
- Helping with symptom management.
Narcolepsy is a rare disorder, the main symptom of which is excessive daytime sleepiness. It is otherwise quite different from obstructive sleep apnoea/hypopnoea syndrome, which has physiological causes. Narcolepsy is a neurological condition affecting the control of wakefulness and sleep. Whatson (2004) describes it as ‘the intrusion of the dreaming state (called REM or rapid eye movement) into the waking state’. It is typified by:
- Irresistible daytime sleepiness, which may occur anywhere and any time. For example, while walking, talking or eating;
- Cataplexy causing sudden muscle weakness, which sometimes appears to be triggered by emotional reactions such as laughing or crying;
- Hallucinations on falling asleep or waking;
- Interrupted nocturnal sleep.
Narcolepsy affects young people, with symptoms commonly manifesting for the first time in teenagers, whereas other sleep disorders like sleep apnoea and periodic limb movement disorder are more common in middle age.
Cataplexy accompanying daytime sleep attacks makes a clinical diagnosis of narcolepsy easy. However, this combination is uncommon, so diagnosis usually involves study in a sleep centre to record nocturnal sleep patterns.
It may also include a multiple sleep latency test, which involves several ‘power naps’, during which brain activity, muscle tone and eye movement are studied. Again use of the Epworth Sleepiness Scale score and a full history are essential, as is the elimination of alternative diagnoses such as epilepsy.
Although there is no cure for the condition, the symptoms of narcolepsy can be dramatically improved. Stimulant drugs may be prescribed for excessive daytime sleepiness, while certain tricyclic antidepressant drugs such as clomipramine can improve cataplexy. These reduce the tendency to sleep at inappropriate times. Scheduling daytime naps can also improve alertness.
Periodic limb movement disorder
Periodic limb movement disorder and the frequently associated disorder of restless leg syndrome cause distressing sensations in the legs and an irresistible urge to move.
The symptoms occur during rest, either sitting or lying down and are relieved by moving around. Although symptoms initially occur at night, as the syndrome progresses, they start to occur earlier in the day and become more intense at night.
- This article has been double-blind peer-reviewed.
For related articles on this subject and links to relevant websites see www.nursingtimes.net
Each week Nursing Times publishes a guided learning article with reflection points to help you with your CPD. After reading the article you should be able to:
- Know how obstructive sleep apnoea/hypopnoea syndrome is diagnosed.
- Understand the problems the syndrome causes through daytime sleepiness.
- Be familiar with the treatments available.
- Understand the nurses’ role in diagnosis and management of obstructive sleep apnoea/hypopnoea syndrome.
Use the following points to write a reflection for your PREP portfolio:
- Outline where you work and why this article is relevant;
- Summarise the main points on obstructive sleep apnoea/hypopnoea syndrome;
- Identify a new piece of information you have learnt about obstructive sleep apnoea/hypopnoea syndrome;
- Outline how you intend to use this information in your future practice and how you will follow up what you have learnt.