Obstructive Sleep Apnoea - a GP quizzes a consultant to take a key condition beyond the textbook
GP Dr Alex Williams and
Dr David Halpin discuss referral criteria and advances in therapies
How is the initial diagnosis made?
What are the symptoms that suggest obstructive sleep apnoea?
Patients usually present with one of three symptoms. They may complain of excessive daytime tiredness, falling asleep at work or perhaps when driving.
Often it is anxious partners who bring them in, because they notice they stop breathing while they are asleep. Sometimes they are just referred because of snoring and during the course of the consultation it emerges that they are also tired.
Are there any aids to diagnosis?
The first thing is to take an adequate history. It's very revealing to talk to people about their sleep patterns. Excessive somnolence often relates to a lack of sleep at night because they go to bed late, or get up early, or are on shift work. Sometimes they are actually referred because they are insomniacs rather then hypersomnolent and that causes confusion.
If hypersomnolence leads to them falling asleep in unusual settings, such as when talking to someone or eating a meal, that is usually significant.
Once it is clear from the history there is a hypersomnolence associated with snoring, one of the most useful screening tests is the Epworth sleepiness scale (page 67). This is an eight-question scale where patients rate a number of situations on whether they would never doze or whether there was a slight, moderate or high chance of dozing.
Each of these is scored from zero (no chance of dozing) to three (high chance) and the total added up. A score above 10 is suggestive of a problem with excessive somnolence.
Confirming diagnosis with a sleep study
Which patients do you refer for a sleep study?
I refer anyone I suspect of having obstructive sleep apnoea, meaning they give a good clinical history and have a raised Epworth sleepiness scale score.
One or two patients perhaps don't give a good history but have other features such as acromegaly or are grossly obese who you think may be suffering from obstructive
What are significant results from performing a sleep study?
There are different technologies used to perform sleep studies, but essentially most look at some measure of oxygen levels, usually pulse oximetry combined with either nasal airflow or chest wall movement.
A positive study shows evidence of either hypoventilation or apnoeas associated with falls in oxygen saturation. If you are just using apnoeas and hypopnoeas then you are counting the total number of events and using that as the criteria for diagnosis.
Sometimes it is useful to actually inspect the trace and look for a pattern of hypoventilation associated with a dip and seeing that on a repetitive basis is highly suggestive of the diagnosis. In my experience most patients can actually sleep adequately when they are undergoing the sleep study, but if you find the process interferes with the pattern of their sleep, the study can give you a false negative.
By inspecting the recordings it is often possible to get an indication that the patient is suffering from obstructive sleep apnoea even if the numbers don't quite add up.
Which snorers do you refer to ENT?
Which patients with snoring do you refer to
your ENT colleagues?
Well in fact it is a bit of a two-way traffic. A lot of patients who have obstructive sleep apnoea are initially referred to ENT surgeons and in our local practice most of those are referred on to me for treatment with continuous positive airways pressure (CPAP).
If I see somebody whose principal complaint is snoring and I have excluded obstructive sleep apnoea through a sleep study, or the related condition of upper airways resistance syndrome also associated with somnolence, I would perhaps refer some of them to the ENT surgeons if the snoring is causing major problems.
Of course, there is the moral dilemma that snoring usually doesn't disturb the patient but does disturb their partner. To operate on someone for somebody else's benefit raises interesting questions.
Are there lifestyle changes that can affect symptoms?
One of the risk factors for obstructive sleep apnoea is obesity and attempts to lose weight can be beneficial. Unfortunately, many patients with obstructive sleep apnoea find it very difficult to lose weight.
There is physiological evidence there may be neuroendocrine changes that make it difficult for them to lose weight, so it is not just that they are not trying. Their symptoms may improve if they can succeed in losing weight.
The other things that can exacerbate sleep apnoea are alcohol drunk soon before going to bed (increases the muscle relaxation) and the use of sleep tablets, which again increases muscle relaxation.
Continuous positive airways pressure is treatment of choice
Which patients do you consider for continuous positive airways pressure?
I think all the studies show CPAP is the treatment of choice for obstructive sleep apnoea but the disadvantage is that patients have to wear a mask and headgear every night. Many don't like doing this, or at least don't like doing it until they see the benefits. I recommend that anyone who has a positive sleep study should have a trial of CPAP.
Most patients find it beneficial and are happy to continue with it. If they are not prepared to continue, occasionally I try other approaches such as mandibular advancement devices.
If all else fails then I sometimes refer them back to ENT surgeons for consideration of surgery.
I am always cautious about the long-term benefits of this approach.
Are there developments in technology to make masks more acceptable?
The mask is an area of research in obstructive sleep apnoea that is advancing rapidly. The basic principle of CPAP remains the same but the interface with the patient is changing.
Essentially there are full-face masks, which cover the nose and the mouth, that we tend not to use.
The masks that just cover the nose are the most common form and increasingly there are masks available that fit into the nostrils, reducing some of the claustrophobia and pressure effects.
Different companies are developing new masks all the time. If patients are having problems with their mask it is always worth trying one of the many varieties available.
Epworth sleepiness scale
How likely are you to doze off or fall asleep in the following situations?
Use the following scale to chose 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
· Sitting and reading
· Watching TV
· Sitting, inactive, in a public place
· Passenger in a car for an hour without a break
· Lying down to rest in the afternoon
· Sitting and talking to someone
· Sitting quietly after lunch with no alcohol
· In a car, while stopped for a few minutes in the traffic
What implications are there for driving?
Does obstructive sleep apnoea have any implications for driving?
Yes, this is one of the most important issues. There is good evidence for an increased incidence of road traffic accidents in patients who suffer from obstructive sleep apnoea.
The accidents themselves can be more damaging because there is no attempt to brake. Patients who have a diagnosis of obstructive sleep apnoea and who are somnolent when driving should not drive until their condition has been adequately treated. They should notify the DVLA and their insurance companies about this.
Would you consider treatment
of OSA a success?
Yes. It is one of the most satisfying conditions to treat. Patients come back with their lives transformed. They feel awake again, they can concentrate at work, they can enjoy life, they can drive and they feel new people as a result of the treatment.There aren't many conditions that you can treat and the result is such a positive outcome.