Sleep apnoea can cause serious morbidity, especially in patients with COPD, yet many cases remain undetected, says Dr Peter Hutchison

The prevalence of obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is estimated at 1-2% in men aged between 30 and 65 years old and 0.5-1% in women of the same age.1 An average GP list of 1800 patients is therefore likely to have as many as 15 cases, most of which are unrecognised.

OSAHS is a condition in which repeated episodes of upper airways obstruction disrupt natural sleep resulting in daytime sleepiness.

It causes substantial morbidity (Box 1, below) but, because the symptoms are of an ill-defined and vague nature, usually neither patient nor doctor spots the possible cause of the problem. Furthermore, in cases where the condition is suspected, there may be delays in getting the diagnosis confirmed as there is great variation in the provision of facilities for investigation and treatment.

Box 1: Features of OSAHS
  • Excessive daytime sleepiness
  • Impaired concentration
  • Snoring
  • Unrefreshing sleep
  • Choking episodes during sleep
  • Witnessed apnoeas
  • Restless sleep
  • Irritability/personality change
  • Nocturia
  • Decreased libido
  • Hypertension
  • Accidents - particularly when driving
  • It is important to consider OSAHS in problem patients who complain of being tired all the time or being irritable with poor concentration.

    Sleepiness is estimated to cause 20% of motorway accidents and is associated with both increased rates and severity of accidents.1 There is evidence for a 1.3 to 12-fold increase in accident rates among patients with OSAHS. The estimated cost of one fatal road traffic accident in the UK is around £1 250 000.2

    It is hoped that the SIGN guideline on the management of obstructive sleep apnoea/hypopnoea syndrome in adults will help to reduce the medical, social and financial costs of excessive sleepiness.

    Guideline methodology

    The guideline development group included GPs, respiratory physicians, ENT surgeons, nurses, scientific officers, representatives of the British Thoracic Society and lay representation.

    A systematic literature review was carried out using a search strategy devised by members of the guideline development group. Databases searched included Medline, Embase and the Cochrane Library. The Medline version of the main search strategies is available on the SIGN website (www.sign.ac.uk), in the section covering supporting material for published guidelines.

    The group then established levels of evidence for the various questions posed. Each article identified by the search was critically appraised and evidence tables were created. Recommendations were debated and graded according to the level of evidence (Figure 1, below). Following consultation at an open national meeting, specialist reviewers were asked to comment on the first draft of the guideline before publication of the final document in June 2003.

    Figure 1: Key to evidence statements and grades of recommendations

    Diagnosis of OSAHS

    In OSAHS, the upper airway collapses during sleep, becoming totally or partly obstructed. This produces an increase in inspiratory effort to try to overcome the narrowing of the airway. This in turn leads to a transient arousal from deep sleep to lighter sleep or wakefulness, when muscular tone returns to open up the airway. This occurs repeatedly, destroying the quality of sleep.

    Risk factors include increasing age, male gender, obesity, sedative drugs, smoking and alcohol consumption.4

    When a patient complains of feeling tired all the time it is important to ask if he or she means excessive sleepiness. This is a very subjective judgement, which can be quantified by the use of the Epworth Sleepiness Scale (Figure 2, below).5 In clinical practice this is a quick, easy and useful tool to try to identify just how the problem affects a patient’s life. Both the patient and his/her partner should complete it.

    Figure 2: The Epworth sleepiness scale
    How likely are you to doze off or fall asleep in the following situations in contrast to just feeling tired? This refers to your usual way of life in recent times. Even if you have not done some of these things, try to work out how they would have affected you.Use the following scale to choose the most appropriate number for each situation.

    0 = would never doze

    1 = slight chance of dozing

    2 = moderate chance of dozing

    3 = high chance of dozing

    Situation Chance of dozing

    Sitting and reading

     
    Watching TV  
    Sitting inactive in a public place (e.g. a theatre or a meeting)  
    As a passenger in a car for an hour without a break  
    Lying down to rest in the afternoon when circumstances permit  
    Sitting and talking to someone  
    Sitting quietly after a lunch without alcohol  
    In a car, while stopped for a few minutes in traffic  
    TOTAL (max. 24)
    Normal <11 points
    Mild subjective daytime sleepiness 11 to 14 points
    Moderate subjective daytime sleepiness 15 to 18 points
    Severe subjective daytime sleepiness >18 points

    Other causes of impaired sleep or daytime sleepiness, for example depression, shift work, drugs or hypothyroidism, must be borne in mind when making the diagnosis.

    Referral

    Investigating patients with suspected OSAHS involves a limited sleep study, measuring parameters such as oximetry, respiratory movement and airflow. This can be done at home but is more commonly performed in a sleep clinic, usually linked to a department of respiratory medicine.

    Severity of OSAHS is measured by the apnoea/hypopnoea index (AHI) – the number of apnoea/hypopnoea events per hour.6 Mild OSAHS is defined as from 5 to 14, moderate 15 to 30, and severe more than 30 per hour.

    Urgent assessment is recommended for patients with chronic obstructive pulmonary disease, who are at risk of decompensation with cor pulmonale or hypercapnic respiratory failure, and for individuals in whom daytime sleepiness puts them or others at risk, such as those who drive for a living.

    Treatment

    Only two forms of treatment had evidence robust enough to warrant grade A recommendations. These were continuous positive airway pressure (CPAP) 7 and an intra-oral device (IOD).8

    There is level 1+ evidence of improvement in various parameters for functional status, including sleepiness while driving, following both CPAP and IOD therapy.

    Advice to stop smoking 4 and to lose weight 9 seems sensible although these measures show little correlation with improvement in the AHI. If obesity is thought to be a contributing factor, however, weight reduction is recommended because it may allow therapy to be discontinued (grade C – based on level 2+ case control or cohort studies). Medication 10 and surgical intervention, 11 for example uvulopalatopharyngoplasty, were shown not to be helpful. Indeed, palatal surgery, for example as a treatment for snoring, can prevent the successful use of CPAP,12 so snorers must be checked for OSAHS before any surgery of this type.

    CPAP is the treatment of choice, having the greatest effect on AHI. In CPAP therapy a gentle flow of air is applied through the nose via a sealed mask keeping the pressure in the throat above atmospheric pressure to maintain patency of the airway through the night.

    An IOD resembles a pair of gumshields worn on the upper and lower teeth, attached in such a way that the mandible is held slightly forwards in order to open up the airway.

    Although IOD is less effective than CPAP, some studies revealed a significant patient preference for an IOD, so this is a serious alternative for those who cannot tolerate the mask and pump. It is also an appropriate therapy for snoring. Although there is only a level 4 evidence base (i.e. expert opinion with no research backing), following general anaesthesia, a patient with severe OSAHS is more likely to need care in a high dependency or intensive care unit and intubation is more difficult.

    Figure 3a: Front of the quick reference guide
    Figure 3b: The reverse of the quick reference guide

    Patient information

    The guideline provides a useful section on information for patients and their families, explaining what the condition is and how it can be treated. Patients must be advised not to drive if sleepy. Falling asleep at the wheel is a serious criminal offence punishable by imprisonment.

    If OSAHS is confirmed, the patient’s GP must be informed and the patient must be told, verbally and in writing, to inform the DVLA. The patient should also inform his or her insurance company.

    Driving will be permitted once the patient has been satisfactorily treated; Group 1 drivers will have to submit a consultant’s report to the DVLA.

    Conclusion

    Our first task is to identify undiagnosed sufferers of obstructive sleep apnoea/hypopnoea syndrome, especially those most at risk, such as individuals with COPD, and those in whom the condition places them at particular risk of an accident because of the nature of their work, e.g. individuals operating dangerous machinery and drivers.

    We therefore need to consider OSAHS when faced with a patient who is "tired all the time” or irritable or who complains of impaired concentration. If the diagnosis of OSAHS is confirmed and treatment tolerated, substantial benefit may be gained.

    Referral for investigation and treatment will require a substantial increase in resources invested in sleep clinics. Research is also needed to strengthen the evidence base and answer questions about, for example, the association between OSAHS and hypertension.

    SIGN 73. Management of obstructive sleep apnoea/hypopnoea syndrome in adults can be downloaded free of charge from the SIGN website: www.sign.ac.uk

    References

    1. Young T, Palta M, Dempsey J, Skatrud J,Weber S, Badr S. The occurrence of sleep-disordered breathing among middle-aged adults. N Eng J Med 1993; 328:1230-5.
    2. Horne JA, Reyner LA. Sleep related vehicle accidents. Br Med J 1995; 310: 565-7.
    3. Department of Environment, Transport and the Regions. Highways economics note No 1. 1999. London: DETR, 2000.
    4. Jennum P, Sjol A. Epidemiology of snoring and obstructive sleep apnoea in a Danish population, age 30-60. J Sleep Res 1992; 1:240-4.
    5. Johns MW.A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep 1991; 14: 540-5.
    6. Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research.The Report of an American Academy of Sleep Medicine Task Force. Sleep 1999; 22: 667-9.
    7. Wright J, White J, Ducharme F. Continuous positive airways pressure for obstructive sleep apnoea (Cochrane Review). In: The Cochrane Library, Issue 1,2002. Oxford: Update Software.
    8. Ferguson KA, Ono T, Lowe AA, al Majed S, Love LL, Fleetham JA. A short-term controlled trial of an adjustable oral appliance for the treatment of mild to moderate obstructive sleep apnoea. Thorax 1997; 52: 362-8.
    9. Smith PL, Gold AR, Meyers DA, Haponik EF, Bleecker ER.Weight loss in mildly to moderately obese patients with obstructive sleep apnea. Ann Intern Med 1985; 103: 850-5.
    10. Hudgel DW, Thanakitcharu S. Pharmacologic treatment of sleep-disordered breathing. Am J Respir Crit Care Med 1998; 158: 691-9.
    11. Sher AE,Schechtman KB,Piccirillo JF.The efficacy of surgical modifications of the upper airway in adults with obstructive sleep apnea syndrome. Sleep 1996; 19:156-77.
    12. Mortimore IL, Bradley PA, Murray JA, Douglas NJ. Uvulopalatopharyngoplasty may compromise nasal CPAP therapy in sleep apnea syndrome. Am J Respir Crit Care Med 1996; 154: 1759-62.

    Guidelines in Practice, December 2003, Volume 6(12)
    © 2003 MGP Ltd
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