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Obesity and OSAS

Detecting and treating sleep apnoea

Fewer bariatric patients had OSAS than expected
Sleep medicine includes a lot more conditions than OSAS
Treating sleeps disorders is cost effective, as is treating obesity
Dr Alwyn Foden consultant respiratory physician, County Durham and Darlington NHS Trust

Obstructive sleep apnoea syndrome (OSAS) is often associated with obesity, however, according to Dr Alwyn Foden consultant respiratory physician, County Durham and Darlington NHS Trust, obesity is not the only predisposing factor.

Foden also said that in their experience far fewer bariatric patients have OSAS than expected and they have not seen any surgical “cures” but there are definite improvements in the severity and ease of management.

Speaking at the 1st Annual Durham & Darlington Obesity & Bariatric Symposium, he outlined the prevalence of sleeping problems with one in three American adults experiencing sleep disorders. Sleep disorders are estimated to cost the US economy $100 billion per year.

“There is more to sleep medicine than snoring and possible associated apnoeas,” said Dr Alwyn Foden. “And not treating them is costly and potentially dangerous.”

According to Foden, there is a long list of sleep disorders - nearly 100 - including dyssomnias (intrinsic and extrinsic sleep disorders) parasomnias (arousal disorders, sleep-wake transition disorders) and sleep disorders with medical conditions (mental, neurological and other medical disorders).

OSAS, an intrinsic sleep disorder, is defined as daytime sleepiness not explained by other factors with two or more of loud snoring, choking/gasping during sleep, recurrent nocturnal awakening.  Predisposing factors include increasing age, male gender, obesity, sedative drugs and alcohol (SIGN Guideline #73)

The incidence of OSAS in the US and Europe is estimated to be between 25-40% of the adult population, although the condition is thought to be largely underdiagnosed, with only one in four patients having a diagnosis.

However, there are also associated links between obesity and daytime sleepiness with insomnia, uncontrolled diabetes, heart failure and hypothyroidism.


“There are no randomised trials that show weight loss, sleep hygiene and exercise are effective in OSAS, as shown by a Cochrane Review in 2001,” said Foden. “Alcohol and sedatives have been shown to both potentiate airway closure via enhanced airway collapsibility or depressed arousal.”

As a result, clinicians are largely left with aggressive weight loss measures such as bariatric surgery and CPAP treatment.

Clinical approach

When undertaking a clinical diagnosis, he said, it is important to differentiate daytime sleepiness from simple tiredness and exclude other causes of sleepiness. It is also essential to look for enlarged tonsils, a small jaw, nasal congestion, chronic obstructive pulmonary disease, asthma, respiratory failure and heart failure.

The Epworth Sleepiness Score (ESS), described by Johns et al, is a useful but not very sensitive scoring system, said Foden. ESS uses a scale of 0 to 3 to rate eight common activities, giving a maximum possible score of 24. Johns et al said a score over 11 was suggestive of sleep apnoea, although it is now accepted that a patient can have a low ESS score and have OSAS

Bariatric surgery

Foden also highlighted the paucity of evidence supporting the notion that bariatric surgery cures OSAS. “In a recent review of bariatric surgery by Hng Kn and Ang, the authors noted in the introduction that there is an epidemic of obesity and that it causes OSAS amongst a host of other conditions. However, OSAS is not mentioned in the paper again,” he said.  Although another study following patients up for two years post-bariatric surgery showed a significant decrease in OSAS symptoms and snoring.

A double blind randomised sham controlled trial showed no change in abdominal adipose tissue distribution after eight weeks of therapeutic continuous positive airway pressure (CPAP), supporting that CPAP helps OSAS but not weight loss

“In our experience, a lot of patients awaiting bariatric surgery don’t have OSAS, as evidenced by sleep studies even with high ESS,” said Foden. “Those that lose a lot of weight after bariatric surgery have a marked improvement in snoring, but the OSAS is not cured although it is easier to control. Obesity hypoventilation, without OSAS, would appear to be cured.

Any patient that the bariatric service or the GP thinks might have a sleep related breathing disorder is referred to the Sleep Clinic. If the study is positive for OSAS, they are prescribed a nasal CPAP regimen. Patients are them followed up to and beyond the surgery.

“Those that are positive for OSAS before surgery are probably going to be on CPAP for a long time but hopefully with lower pressures,” he said. Sometimes we will also involve the rhinology service, and occasionally to the maxilla-facial service.

He concluded by stating that sleep medicine includes a lot more conditions than OSAS and therefore sleepy patients in the bariatric service could also have anyone of the other conditions. Treating the disorders is cost effective, as is treating obesity.

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