Snoring and Obstructive Sleep Apnoea



OVERVIEW



  • SRBD is a spectrum of conditions ranging from simple snoring to severe OSAHS that develops with increasing reduction in airflow and has a major impact on patient life (socially and medically)
  • A major risk factor is obesity and effective strategies to achieve long-term weight loss are desperately needed to curtail the concurrent epidemics of obesity and obstructive sleep apnoea
  • The gold standard for diagnosis is polysomnography but this is not always available and other sleep studies are used in conjunction with a detail history (with the patient’s partner)and thorough examination
  • Treatment of the SRBD depends on its severity and ranges from lifestyle changes and simple surgery amongst simple snorers to mild OSAHS patients whilst patients with moderate to severe OSAHS benefiting from CPAP
  • SRBD is common in children and the most common treatment choice for paediatric OSAHS is adenotonsillectomy




Snoring and obstructive sleep apnoea syndrome (OSAHS) are different degrees of a broadly identified disorder; sleep-related breathing disorder (SRBD). Identifying SRBDs is important as they have a major impact on a patient’s life. The medical implications of SRBDs such as increased risk of stroke, hypertension and other cardiovascular conditions such as arrhythmias and myocardial ischaemia are well-documented. Daytime somnolence poses a risk to the individual and public with respect to road traffic accidents. Lastly, marital and relationship disharmony can occur as a consequence of simple snoring; significant improvement in the quality of life is achieved with successful surgery.


Spectrum of the condition


SRBD results from partial or total obstruction of the upper airway. The pathogenesis is multifactorial; reduced muscle tone during sleep and certain anatomical variations in the upper airway predisposing to the condition. Increasing upper airway resistance results in progressive worsening of the disease. SRBD is a spectrum of conditions (Figure 19.1) ranging from simple snoring to severe OSAHS that develops with increasing reduction in airflow.



Figure 19.1 The continuum of sleep-disordered breathing. UARS, upper airway resistance syndrome; OSA, obstructive sleep apnoea; OSAHS, obstructive sleep apnoea hypopnea syndrome.

19.1

Depending on the degree of obstruction and associated symptoms, individuals are categorised into one of the following categories:



Simple snoring is categorised by disruptive low frequency sound produced during partial obstruction and vibration of the upper airway without impact on the patient’s sleep pattern. This usually arises from soft palate, but the tonsils, epiglottis and the base of the tongue may also contribute in up to 30% of cases. Twenty-five per cent of the population are habitual snorers.

Upper airways resistance syndrome (UARS) is categorised by increased sleep disruption and excessive daytime sleepiness (EDS) without evidence of obstructive apnoeas or de-saturations.

Obstructive sleep apnoea hypopnoea syndrome (OSAHS) is categorised by the coexistence of EDS and interrupted and repeated upper airway collapse during sleep with associated desaturations.

Progression of airway collapse and obstruction leads to either complete with total cessation of airflow (apnoea) or partial with significant hypoventilation (hypopnoea). Severity of OSAHS is determined by frequency of the apnoeas and hypopnoea called the apnoea/hypopnoea index (AHI) (Table 19.1).


Table 19.1 Categories of severity of OSAHS.















Severity of OSAHS AHI (apnoea/hypopnoea events per hour)
Mild 5–14
Moderate 15–30
Severe greater than 30

Clinically significant OSAHS is only likely to be present when the AHI is greater than 15 events per hour in association with unexplained EDS.


Aetiology


The airway between the posterior end of the nose and the larynx is unprotected by cartilaginous or bony structures and reliant on muscle tone for its patency. SRBD only occurs during sleep when pharyngeal muscle tone falls progressively as sleep condenses to deeper levels. This phenomenon is present in all humans and yet not all humans have SRBD. Abnormalities in both “upper airway” size and muscle activity appear to contribute to its pathogenesis.


Factors found to increase the risk of SRBD are:



Gender—Men have between a twofold and a fivefold increased risk of OSAHS compared with women matched for age and weight. Sex hormones influence upper body obesity and are probably why OSAHS is less common in premenopausal women than postmenopausal women or in men.

Obesity—This is the most important risk factor, and prevalence of SRBD has been shown to directly correlate with the body mass index (BMI). Seventy per cent of individuals with a BMI of 40 or greater suffer with OSAHS. Central obesity indicators such as neck circumference index and waist : hip ratio are recognised as better predictors of OSAHS than BMI.

Obstructive upper airway anatomy—Craniofacial abnormalities are associated with a higher prevalence of SRBD. Features such as retrognathia, tonsillar hypertrophy, enlarged tongue or soft palate, inferiorly positioned hyoid bone, maxillary and mandibular retroposition, and decreased posterior airway space can narrow upper airway dimensions and promote the occurrence of OSAHS during sleep. Decreased nasal airway due to turbinate hypertrophy, septal deviations or nasal polyposis increases upper airway resistance and can contribute, but is unlikely to be the sole cause for SRBD.

Other risk factors—given in Table 19.2.

Table 19.2 Other associated risk factors of OSAHS.



























Risk factor Associations Salient points
Age Progressive increase in prevalence of SRBD in 6-7th decades Narrower and possibly more collapsible upper airways seen with increasing age
Hereditary Two- to fourfold greater In first degree relatives
Medical history

Hypothyroidism

Acromegaly

Neuromuscular diseases

Chronic lung disease* (*not a direct risk for SRBD)

Due to craniofacial anomaly

Central apnoeas are more likely

OSAHS is more severe with deeper events de-saturation due to hypo-ventilation and lower lung reserve
Social history

Smoking

Alcohol
Drugs

Hypnotics

Opioids
 Central depression increase the risk of SRBD

Consequences of sleep-related breathing disorders

Related posts:

  1. Facial Pain
  2. Acoustic Neuromas and Other Cerebellopontine Angle Tumours
  3. Hoarseness and Voice Disorders
  4. Swallowing Problems

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Jun 4, 2016 | Posted by in OTOLARYNGOLOGY | Comments Off on Snoring and Obstructive Sleep Apnoea

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