Daytime tiredness can have serious consequences so it is important to find the underlying cause, says Dr Peter Saul
Before I came across the recent SIGN guideline on obstructive sleep apnoea/hypopnoea syndrome (OSAHS) I was confident that I seldom saw a patient with the condition. However, the guideline has opened my eyes and made me realise that I probably see a considerable number but miss the diagnosis, perhaps too often attributing symptoms to psychological causes.
The guideline highlights the fact that OSAHS is fairly common, affecting 1-2% of middle-aged men,with around half that proportion of women affected. Perhaps GPs should now consider the condition in any patient complaining of daytime tiredness, especially those who smoke, are obese or take sedative drugs or alcohol.
The guideline provides a good reminder of the causes and pathophysiology. OSAHS results from partial or complete collapse of the upper airway for short periods. This causes the patient to wake briefly before returning to deep sleep, when the problem recurs. The normal sleep pattern is seriously disturbed, leading to daytime sleepiness.
Most GPs would recognise the importance of taking a history from the patientÍs partner as well as the patient, and this is reinforced in the guideline. I found the description of the Epworth Sleepiness Scale interesting. A questionnaire completed by patient and partner is used to assess the patientÍs tendency to fall asleep in various situations. High scores can raise the probability of OSAHS.
Evaluation by the GP will help to identify those most severely affected – those who suffer interference with their daytime occupation and those with COPD. It will also help to rule out many conditions that mimic OSAHS, and here the guideline offers a useful list of differential diagnoses.
The guideline makes assumptions about access to sleep clinics, but I suspect this is yet another area where there are serious deficiencies in resourcing. Diagnostic confirmation and treatment relies on these clinics.
To back up initial GP assessment, the guideline identifies a variety of investigations, ranging from imaging techniques through pulse oximetry to full polysomnography.These are definitely the realm of the specialist, but it is useful to know what they are.
As is usual in guidelines, the usefulness and evidence base of investigation and treatment are reviewed. It is no surprise to realise that there is no therapeutic quick fix for OSAHS.
Commonsense behavioural measures are identified, such as weight loss, smoking cessation and avoiding sleeping on the back, and these can be encouraged by GPs. However, more severe cases should be referred to the sleep clinic where continuous positive airways pressure is a mainstay of treatment.
Not surprisingly, many patients find this therapy unacceptable, and in less severe cases intra-oral devices, designed to open the upper airway by pushing the mandible forward, are an alternative. It is not the custom of guidelines to be rich in illustrations, but I would have liked to see examples of these devices.
Drastic measures such as tracheostomy can be successful, but in general it is pointless to refer patients for other surgical procedures.
Now that OSAHS has been highlighted I will be less ready to put symptoms of daytime tiredness down to psychological factors. I will try out the sleep questionnaire and find out about local access to a sleep clinic.
OSAHS is an important condition, not least because of the risks sufferers bear when driving or operating machinery. It is depressing that effective treatment is relatively invasive and needs to be lifelong.
SIGN 73. Management of Obstructive Sleep Apnoea/Hypopnoea Syndrome in Adults – A national clinical guideline can be downloaded free of charge from the SIGN website: www.sign.ac.uk