Wake-up call: OBSTRUCTIVE SLEEP APNOEA

Daytime sleepiness is a major incapacitating symptom, which can have serious consequences. It can affect relationships, work, education and alertness – which can lead to accidents.1 Obstructive sleep apnoea (OSA) is one of the causes of disruptive sleep, resulting in daytime sleepiness.

Sleep apnoea can be defined as the cessation of breathing during sleep. There are three main types: obstructive, central and mixed apnoea. However, OSA is the most common form.2

A person suffering from OSA will experience episodes of heavy snoring that begin soon after falling asleep. The snoring proceeds at a regular pace for a period of time, often becoming louder, but is then interrupted by a long silent period without any breathing [apnoea]. The apnoea is then interrupted by a loud snort and gasp, and the snoring returns to its regular pace.

During the apnoeic stage, the sufferer is unable to inhale oxygen and exhale carbon dioxide, resulting in increased levels of carbon dioxide in the blood. The reduction in oxygen and the increase in carbon dioxide triggers transient arousal to a lighter sleep or wakefulness. A few of these arousals do not matter, but where there are many, people with OSA can experience severe daytime sleepiness. This occurs during activities such as reading, watching television, or driving on motorways. However, when the sleepiness becomes worse, it begins to interfere with most activities, and the person can fall asleep while talking or even eating.

Central and mixed sleep apnoea

Central sleep apnoea is rare. It is defined as a neurological condition causing cessation of all respiratory effort during sleep, usually with reductions in blood oxygen saturation. The airway remains open, but the nerve signals controlling the muscles are not regulated by the brain, resulting in fluctuations in the levels of carbon dioxide in the blood (CO2). The lower CO2 can result in breathing becoming very slow or stopping altogether. The individual is then aroused from sleep by an automatic breathing reflex.

Mixed apnoea is a combination of OSA and central apnoea. An episode usually starts with a central component, and then becomes obstructive in nature.2

Who is affected?

OSA becomes more likely with increasing age. It has been estimated that up to 4% of middle-aged men and up to 2% of middle-aged women have the condition.3 Most patients are overweight and a significant proportion have short, thick necks with a circumference of 17 inches or more. They may also have associated structural narrowing of the upper airways or a receding jaw. Characteristics of OSA include morning headaches, poor physical and intellectual performance and irritability.

Effects on work

Obstructive sleep apnoea can have an effect on an individual’s work performance. Studies undertaken to assess the effects of sleep deprivation have found that innovative thinking and decision-making abilities have been reduced. Sleep loss can impair an individual’s ability to make flexible decisions or quick rational judgements during an unforeseen crisis.4 This is particularly relevant in safety-critical occupations, or for individuals who spend the majority of their working time driving.

Sleep loss can also affect an individual’s ability to recall facts quickly, and those deprived of sleep are less articulate, especially when vocalising thoughts. It would also appear to impair their ability to provide novel answers quickly.4 Sleepy individuals also have problems finding the right words and delivering ideas, which can have an impact on their communication skills.

The effects of sleep deprivation on our ability to think, communicate and make decisions can affect every aspect of our working life. Research into accident causation has found that in major disasters – such as the Exxon Valdez oil spill in 1989 – long working hours, coupled with a disturbed sleep pattern, contributed to a decision-making error.5

Relationships with colleagues can also suffer due to tiredness, fatigue and mood disturbance, which can affect team dynamics and working relationships.

Difficulties in sustained alertness should be taken into account when undertaking health screening/surveillance of workers in occupations where activities could be hazardous to individuals. Such workers can include airline pilots, air-traffic controllers, long-distance lorry drivers, and those who work with potentially dangerous machinery and processes. Those who are found to be at a high risk of reduced alertness should be suspended from duties until they start to respond to adequate treatment.

Diagnosis

The diagnosis for OSA is not straightforward, as there can be many reasons for disturbed sleep. Patients with suspected OSA should be referred by their GP to a respiratory physician for an overnight sleep study. This is undertaken in a sleep laboratory, where polysomnography (a diagnostic test) allows the detailed recording of abnormal breathing events during sleep, such as the electrical activity of the brain, eye movement, muscle activity, heart rate, respiratory effort, airflow, and levels of oxygen in the blood. The results will confirm the diagnosis of OSA.

A detailed medical history is important in the diagnosis process, and should include the patient’s waking and sleeping habits. The Epworth Sleepiness Scale (ESS)6 – where the patient is asked to score the likelihood of falling asleep in eight different situations with different levels of stimulation – may be used to assess the severity of the sleepiness.

Clinical assessment covers measuring the patient’s height, weight, body mass index and neck circumference, and examining the face, mouth and throat for abnormalities that might affect their breathing.

Treatment

The primary aim of treatment for patients with excessive daytime sleepiness is to improve their daytime functioning and quality of life. Treatment is tailored to the individual, based on their medical history and the results of their physical examination. It should address any underlying causes, such as nasal polyps (abnormal lesions) or a receding lower jaw.

Patients should be encouraged to make lifestyle changes to help limit the effects of sleep apnoea, such as losing weight, quitting smoking, drinking less alcohol and avoiding sedatives. While this approach will be of benefit to many patients, there are other options.

Continuous positive airway pressure (CPAP) is the treatment of choice for many with moderate to severe sleep apnoea. The CPAP pump delivers air at low pressure to the upper airways via a plastic tube attached to a nasal mask. The pressure is constant and keeps the airway from collapsing and creating an obstruction. This form of treatment can prevent disrupted sleep and other clinical symptoms of sleep apnoea.7 However, patients commonly experience minor side effects, including nasal irritation, rhinitis, discomfort, claustrophobia and abdominal bloating.

Oral appliances are an alternative for those who are unable to tolerate CPAP therapy. They work by bringing the lower jawbone or tongue forward to keep the airway open. They can be effective at treating snoring and low-level upper airway obstructions, but they are less effective than CPAP.
Surgical techniques have been used for treating patients with obstructive sleep apnoea. Common procedures include the removal of tonsils, polyps and the correction of a deviated septum. However, in clinical trials, further surgery to increase the size of the airway has shown no clear evidence of effectiveness.8

The OH department has a positive role to play in both educating the individual as well as managing the effects of OSA. OH professionals can make a positive contribution by providing health information to those who wish to lose weight, quit smoking or drink less alcohol as part of a programme to limit the effects of sleep apnoea. Liaising with management to make temporary adjustments for employees in safety-critical roles while they are undergoing treatment can also be helpful.

Ann Ramsey (occupational health team manager), Hugh Scott (occupational health adviser), Jackie Kennaugh (occupational health practice nurse) and Hilary Doherty (occupational health practice nurse) all work at British Airways Health Services

Further information

British Snoring and Sleep Apnoea Association, 52 Albert Road North, Reigate, RH2 9EL www.britishsnoring.co.uk

References

1. Adrich M S (1989) Automobile accidents in patients with sleep disorders, Sleep 12: pp487-494
2. Linder D (1995) Sleep Apnoea FAQs, New Technology Publishing Inc. www.healthyresources.com/sleep/apnea/faq/index.html
3. Young T et al (1993) The Occurrence of Sleep-Disordered Breathing Amongst Middle-Aged Adults, New England Journal Medicine 328: pp1230-1235
4. Harrison A, Horne J (1998) Sleeplessness in Loughborough Sleep Deprivation and Cognitive Function, Loughborough Sleep Research Centre www.lboro.ac.uk
5. Hart R (2003) Sleep and the Transportation Industry, A Lecture to the International Association of Airline Nurses, (IAAN) Chicago
6. Johns MW (1991) A New Method for Measuring Daytime Sleepiness, The Epworth Sleepiness Scale (ESS), Sleep 14: pp540-545
7. Scottish Intercollegiate Guidelines Network (June 2003) Management of Obstructive Apnoea Syndrome in Adults, Guideline no. 73 www.sign.ac.uk/index.html
8. Managing Excessive Daytime Sleepiness in Adults (2004) Drugs and Therapeutic Bulletin, July Vol 42, No 7. p52



Comments are closed.