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Obstructive sleep apnea

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Obstructive sleep apnea (spelt "apnoea" in British English) is a "disorder characterized by recurrent apneas during sleep despite persistent respiratory efforts. It is due to upper airway obstruction. The respiratory pauses may induce hypercapnia or hypoxia. Cardiac arrhythmias and elevation of systemic and pulmonary arterial pressures may occur. Frequent partial arousals occur throughout sleep, resulting in relative sleep deprivation and daytime tiredness. Associated conditions include obesity; acromegaly; myxedema; micrognathia; myotonic dystrophy; adenotonsilar dystrophy; and neuromuscular diseases. (From Adams et al., Principles of Neurology, 6th ed, p395)."[1][2]


Polysomnography is the best test and abnormal is a apnea–hypopnea index (AHI) of 5 or greater. The American Academy of Sleep Medicine publishes a diagnostic manual.[3] and guidelines[4]. Moderate to sever OSA is a AHI of 15 or more episodes/hour. However, this test requires a patient to attend a sleep center and is not always required to diagnose sleep apnea.[5] A systematic review in 2000 concluded that the best alternative diagnostic test is not certain.[6]

Testing can be done at home.[7]

History and physical

Age, body mass index, male sex, and snoring are the best predictors of sleep apnea.[8] Obstructive sleep apnea is difficult to diagnose based on the history and physical examinations.[9]

  • A score of more than 5 on the Berlin Questionnaire has a sensitivity of 86% in one study.[10]
  • The Epworth Sleepiness Scale may help diagnose. The original cut-off was proposed to be 10. However, the optimal cut-off level may be 8[11] or 12 if combined with the BMI.[12].
  • The Wisconsin Sleep Questionnaire may help diagnose.[13]
  • Another clinical prediction rules may help diagnose sleep apnea.[14]


Oximetry, which may be performed overnight in a patient's home, is an easier alternative to formal sleep study (polysomnography.

  • In one study, normal overnight oximetry was very sensitive and so if normal, sleep apnea was unlikely.[15] In addition, home oximetry may be equally effect in guiding prescription for automatically self-adjusting continuous positive airway pressure.[16]
  • Another study found that overnight oximetry, defining abnormal as 15 or more 4% desaturations/hour, was very specific, but not sensitive.[17]
  • Sensitivty of overnight oximetry is improved by using a 3% desaturation in oxygen.[18] and lowering the ODI to 5 per hour.[19]
  • Oximetry may identify some patients whose outcomes are not improved by adding polysomnography.[5]


Treatment may lower blood pressure by about 3 - 5 mm Hg.[20][21]

Weight loss

Weight loss of 20 kg with a liquid very low energy diet(2.3 MJ/day) for seven weeks can reduce the AHI by 23 and lead to 20% of patients becoming disease free.[22]

Oral appliances

Regarding oral appliances (mandibular advancement device (MAD)), "CPAP appears to be more effective in improving sleep disordered breathing than OA. The difference in symptomatic response between these two treatments is not significant, although it is not possible to exclude an effect in favour of either therapy. Until there is more definitive evidence on the effectiveness of OA in relation to CPAP, with regard to symptoms and long-term complications, it would appear to be appropriate to recommend OA therapy to patients with mild symptomatic OSAH, and those patients who are unwilling or unable to tolerate CPAP therapy" according to the Cochrane Collaboration.[23]

More recent randomized controlled trials report:

  • Similar findings in that oral appliances (mandibular advancement device (MAD)) are easier to tolerate, but CPAP is reduces the apnea-hypopnea index (AHI) more. Quality-of-life indicators may be better with appliance.[24]
  • MAD may not affect quality of life or daytime sleepiness, though other benefits may occur, among patients with apnea-hypopnea index (AHI) lower than 30.[25]

Continuous positive airway pressure (CPAP)

Several trials have studied continuous positive airway pressure:

  • Patients with Epworth Sleepiness Scale score >10 has a reduction in daytime symptoms.[26]
  • Patients with Epworth Sleepiness Scale score <10 had no reduction in cardiovascular events.[27]

A randomized controlled trial of patients with central sleep apnea concluded "CPAP attenuated central sleep apnea, improved nocturnal oxygenation, increased the ejection fraction, lowered norepinephrine levels, and increased the distance walked in six minutes, it did not affect survival."[28].

Regarding research prior to these trials, the Cochrane Collaboration concluded "CPAP is effective in reducing symptoms of sleepiness and improving quality of life measures in people with moderate and severe obstructive sleep apnoea (OSA). It is more effective than oral appliances in reducing respiratory disturbances in these people but subjective outcomes are more equivocal. Certain people tend to prefer oral appliances to CPAP where both are effective"[29]

Continuous positive airway pressure can be automatically self-adjusting.[16][30]

Bi-level positive airway pressure (BiPAP) is often more tolerable, as it decreases the pressure when the patient exhales, reducing respiratory effort.[31] For both CPAP and BiPAP, there are a wide range of masks, nasal catheters called "nasal pillows", and it may take several devices and expert fitting to find the right appliance for individual patient."The optimum form of CPAP delivery interface remains unclear... nasal pillows or the Oracle oral mask may be useful alternatives when a patient is unable to tolerate conventional nasal masks" according to the Cochrane Collaboration.[29] A heated humidifier in the compressed air path also helps compliance by preventing drying of the nasal mucosa.

Eszopiclone, a sedative, used nightly for 14 nights may provide sustained increase in patient compliance[32]


Regarding medications, "there is insufficient evidence to recommend the use of drug therapy in the treatment of OSA" according to the Cochrane Collaboration.[33]

Oropharyngeal exercises

Oropharyngeal exercises my help.[34]


Regarding surgery, studies "do not provide evidence to support the use of surgery in sleep apnoea/hypopnoea syndrome, as overall significant benefit has not been demonstrated" according to the Cochrane Collaboration.[35]

Compression stockings

A small randomized controlled trial reported that compression stockings reduced the number of apneas and hypopnea, perhaps by "prevention of fluid accumulation in the legs during the day, and its nocturnal displacement into the neck at night."[36]


An AHI over 20 is associated with death.[37]


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