Introduction

Sleep apnoea (aka Obstructive Sleep Apnoea or OSAdescribes a condition in which there are multiple (often frequent) pauses in respiration (“apnoeas”) during sleep, as a result of upper airway collapse, usually at the level of the oropharynx.

The apnoeas in sleep apnoea can range from a few seconds, up to 90 seconds, and cause hyperaemia, hypercapnia and even respiratory acidosis. These resulting clinical effects stimulate the patient to awaken (often unnoticed or not remember by the patient), which re-establishes the airway.

This pattern of frequent apnoeas, following by frequent, brief periods of awakening result in extremely poor quality of sleep, often causing symptoms of tiredness, and in severe cases, the patient falling asleep during the day (e.g. whilst driving).

Typically a result of obesity, mainly in middle age and older patients (although can be seen at any age), it is also seen in children with large tonsils and adenoids.

Sleep apnoea is associated with an increased risk of cardiovascular disease, atrial fibrillation, hypertension and death.

Diagnosis is usually by polysomnography (“sleep study”) in which the respiratory rate and pattern, as well as oxygen saturations are measured whilst the patient is asleep. True polysomnography often also includes EEG monitoring (for phases of sleep), airflow monitoring at the nose and mouth, and electro-occulography to assess for rapid eye movement (REM) sleep.

Management involves weight loss and / or use of CPAP (positive airways pressure) at night to keep the airway open. In children, sleep apnoea is a indication for tonsillectomy.

It is thought that the majority of cases are undiagnosed.

Epidemiology & Aetiology

  • Prevalence about 4% (in men) and 2% (in women) in developed nations
    • Some speculate it may be as high as 9%
  • Incidence is increasing in line with the incidence of obesity
  • Strongly associated with diabetes
  • Risk factors:
    • Obesity – 7% as common in patients with BMI >30
    • Fat deposition around the neck
      • >48cm neck circumference is high risk
      • <37cm is low risk
    • Male
    • Smoking
    • Alcohol
    • Sedative drugs
    • Family history – possibly genetic factors related to shape of jaw
  • Nasal obstruction accounts for about 10% of cases
    • Assess for nasal deformity, polyps, nasal septal deviation

Presentation

  • Excessive daytime sleepiness
    • Consider assessing this using a scale – such as the Epworth Sleepiness Scale
    • Consider investigations with a score >10
    • Urgent referral to sleep specialist (usually respiratory physicians) if score >18 or any recent road traffic accident or near miss
  • Sleep symptoms
    • Snoring
      • Present in 85% of cases of OSA
      • Most people who snore do not have sleep apnoea
    • “Thrashing”
    • Feeling of choking during sleep
    • Most patients are not aware of their sleep symptoms – these symptoms are usually reported by a partner. Partners may report noticing long periods without a breath being taken
  • Waking with a headache
  • Irritability / personality change
  • Decreased libido
  • Difficulty concentrating
  • Partner or other relative may witness apnoeas

Differentials

  • Insufficient sleep (!)
    • Including shift work
  • Hypothyroidism
  • Narcolepsy
  • Depression
  • Drugs
  • Excess alcohol

Diagnosis

Diagnosis of OSA requires a sleep study. The definition of sleep apnoea requires at least five apnoeas per hour recorded on a sleep study, plus symptoms of OSA. A true apnoea is usually defined as >10 seconds without breathing.

  • Mild OSA – 1-14 apnoeas per hour
  • Moderate OSA – 15-30 apnoeas per hour
  • Severe OSA – >30 apnoeas per hour

The gold stand test is polysomnography. This involves an EEG, electro-oculogram (to measure eye movements / REM sleep), and and electromyogram to monitor muscle movement. However, this is expensive and not always available. An appropriate alternative more frequently used is a respiratory monitor and pulse oximetry. It is likely that home testing kits which measure these two metrics only will become more widely used in future.

Associated Diseases

OSA is important because it is associated with a wide range of serious diseases:

Complications

  • Accidents at home, at work and whilst driving due to sleepiness
  • Increased cardiovascular disease risk, and cardiovascular complications such as HTN, coronary artery disease and CCF
  • Irritability, depression and other mood distrubance
  • Increased risk of T2DM

Management

The goal of treatment is to reduce day-time sleepiness and improve day time functioning.

Note that symptom reduction has no correlation with reduction in risk for cardiovascular disease, but that CPAP (and weight loss) has been proven to reduce cardiovascular disease risk.

Management options include:

  • Weight loss – aim for 10-15% of body weight. Can result in complete resolution of OSA. The most effective treatment. Is difficult to achieve.
  • Regular exercise – advise 150 minutes per week of moderate intensity (equivalent to a brisk walk) exercise
  • Avoidance of triggers
    • Cease any drugs suspected of having an effect
    • Advise alcohol within safe drinking limits and no alcohol in the three hours before bed
    • Smoking cessation
  • Sleep advice
    • Practice good sleep hygiene – e.g. similar, regular bed time each night, no food or drink in the last 2 hours before bed, no caffeine after 2pm, avoid looking at screens in the 1 hour before bed
    • Avoid lying on back (supine) – encourage lying on the side
  • CPAP – Continuous positive airways pressure
CPAP Machine

CPAP Machine

 

    • A machine at the bedside which pumps air through a face mask covering the nose, mouth or the entire face. Can be noisy and uncomfortable.
    • CPAP is the mainstay of treatment for most patients – however, many cannot tolerate the mask
    • Can be nasal mask or full face mask
    • Positive pressure keeps the airway open
    • Needs to be worn for 8 hours each night
    • Side effects include:
      • Claustrophpbia
      • Rhinitis
      • Nasal Irritation
    • Symptoms usually recur within a few days of cessation of use of the face mask
    • Successful treatment can reduce blood pressure and greatly reduce the risk of cardiovascular disease
    • Proven to reduce all cause mortality in patients with OSA and hypertension
    • Compliance is poor
A nasal CPAP mask

A nasal CPAP mask

  • Surgery
    • Most commonly in children – for removal of tonsils
    • Occasionally in adults for the same
    • Sometimes used to correct nasal structural defects or other anatomical defects and should be considered first line treatment if an anatomical abnormality is identified
    • Other surgical options include:
      • Uvulopalatopharyngoplasty (UPPP)
      • Radiofrequency ablation of the tongue base
      • Suspension of hyoid bone
      • Advanced of mandible with Maxillofacial surgery (rare)
  • Medication
    • Not usually recommended
    • Steroid nasal sprays may be useful for rhinitis, and oral sprays for large tonsils
    • Amitriptyline may help to increase REM sleep in patients with OSA who cannot tolerate a CPAP mask
  • Oral appliances
    • Commonly used and appear to be safe
    • Common example is a mandibular advancement splint – attach to upper and lower teeth and pull the mandible forwards
    • Can cause arthralgia, tooth pain, excessive salivation and dry mouth
    • Are becoming more widely accepted
    • Evidence is not conclusive, but probably as effective as CPAP in mild to moderate cases
    • Less effective in severe cases

Driving

  • Patients with day-time sleepiness may need to cease driving (depending on the severity)
  • Include a thorough assessment of sleepiness in any driving assessment

References

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