Obstructive Sleep Apnoea (OSA)

 

Definition
  • obstructive sleep apnoea/hyponea syndrome can be defined as the co-existence of excessive daytime sleepiness and irregular breathing at night
  • repeated collapse of upper airway during sleep causing cessation of breathing despite inspiratory effort
  • obstruction may be complete, with total obstruction of the airway (apnoea) or partial (hypopnoea) causing hypoventilation
  • severity measured using the apnoea/hyponoea index (AHI)
Risk factors
  • overweight
  • smoker
  • alcohol
  • sedatives
  • older age group
  • hypothyroidism

 

Clinical features

Nocturnal symptoms

  • loud snoring, majority of snorers do not have OSA
  • choking and restlessness
  • nocturia
  • tiredness, headaches, impaired quality of life and social life, depression and hypersomnolence (falling asleep at inappropriate times) – 24% of people with OSA reported to fall asleep whilst driving at least weekly
  • nocturnal hypoxaemia if prolonged causes hypertension and cardiac problems

Diurnal symptoms

Medical symptoms

Diagnosis
  • history from pt and sleeping partner
  • overnight polysomnography in sleep laboratory or at home, measurements include traces of heart, brain and respiratory activity, oral and nasal airflow as well as sounds and body position
  • subjective assessment of daytime sleepiness using the Epworth Sleepiness Scale

 

Management
  • multidisciplinary care: involves respiratory/thoracic physicians, ENT, Maxillo-Facial surgeons and orthodontists

Management options involve:

  • behavioural modification – weight loss programmes, alcohol avoidance, alteration of sleeping position
  • eliminate aggravating factors – control of chronic obstructive airway disease, asthma, hypothyroidism

Non-surgical options:

  • continuous positive airway pressure (CPAP) delivers continuous air under pressure via tight fitting nasal mask (considered gold standard treatment); disadvantages – noisy, cumbersome and efficacy highly reliant on pt compliance
  • mandibular advancement appliances (MAA) offered as alternative to pts who cannot tolerate CPAP
  • review suggests MMAs have similar treatment efficacy for mild-moderate OSA as CPAP

Surgical options sometimes considered:

  • mandibular or bimaxillary advancement surgery
  • surgery to reposition hyoid
  • surgical correction of nasal and naso-pharyngeal obstructions (septal deviation, polpys etc)

 

Mandibular advancement appliances (MAA)
  • primary action – to increase and stabilize the oropharyngeal and/or hypopharyngeal airway space
  • many designs described, include vacuum formed devices, CoCr, cribbed activator, removable Herbst with intermaxillary elastics; 1 or 2 piece or adjustable appliances
  • resemble functional appliance with protrusive bite (75% maximum protrusion suggested) and as little vertical opening as possible
  • efficacy review identified 14 good quality trials compared MAAs of varying design with inactive devices or other MAAs in mostly mild-moderate OSA pts:

- all MAAs improved AHI

- comparison with inactive appliances and found that mandibular protrusion is crucial

- evidence for specific designs being more effective that others is conflicting, more research is required

  • compliance rate of 52-100% reported

 

References

Ahrens A et al., 2011, A systematic review of the efficacy of oral appliance design in the management of obstructive sleep apnoea, EJO, 33;318-324

Lim J et al., 2006, Oral appliances for obstructive sleep apnoea. Cochrane database of systematic reviews: CD004435

Scottish Intercollegiate Guidelines Network (SIGN), 2003, SIGN 73: Management of obstructive sleep apnoea/ hyponoea syndrome in adults