Week 5/6 - E - Obstructive sleep apnoea - snoring/definition, risk factors, features, complications, diagnosis, treatment

Question 1

What actually is snoring and what causes it?

Answer 1

Snoring is caused by the relaxation of the pharyngeal dilator muscles during sleep (especially during REM) The relaxation causes upper airway narrowing, leading to turbulent airwflow and vibration of the soft palate and tongue base

Question 2

What is obstructive sleep apnoea? What is apnoe defined as?

Answer 2

Obstructive sleep apnoea is the intermittent upper airway collapse in sleep causing apnoeic episodes during sleep Can result in recurrent arousals during sleep/sleep fragmentation (apnoea = cessation of airflow for at least 10 seconds)

Question 3

What are the risk factors for sleep apnoea?

Answer 3

Enlarged tonsil/adenoids Obesity Oropharyngeal deformity Sedative medication

Question 4

What is the typical patient for OSA to occur in? What are the clinical features of OSA?

Answer 4

Typically occurs in an obese, middle aged man Clinical features: Loud snoring Witnessed apnoeas or choking noises while sleeping. Excessive daytime sleepiness (daytime somnolence) Poor sleep quality Morning headache Decreased libido Major impact on daytime function

Question 5

What are the complications of OSA?

Answer 5

Complications include * Pulmonary hypertension (due to hypoventilation, decreased oxygen causing pulmonary vasoconstriction to meet the V/Q mismatch) * Type 2 respiratory failure * Impaired glucose tolerance –> diabetes * Hypertension

Question 6

Diagnosis of OSA What is the questionnaire used that can indicate an abnormal level of daytime sleepiness? What score indicates this?

Answer 6

An Epworth sleepiness questionnaire, which measures perception of sleepiness, is helpful in the diagnosis of obstructive sleep apnoea syndrome (OSAS). The Epworth Sleepiness Score (ESS) is calculated using eight questions, each scored 0–3, which assess the tendency of a person to fall asleep in a variety of situations A total score of >10 indicates abnormal daytime sleepiness

Question 7

Diagnosis of OSA - What simple studies may be carried out to diagnose OSA? What investigation may be carried out at night and what does it monitor? (carried out after referral to ENT/Respiratory)

Answer 7

Simple studies such as pulse oximetry or video recordings may be all that is required for diagnosis Full polysomnography is diagnostic - * monitors O2 sats, * airflow at the nose and mouth, * ECG, * EMG chest and * abdominal wall movements during sleep

Question 8

What is needed for a diagnosis of OSA after a polysomnography is carried out? What is mild, moderate and severe OSAS graded as? Both of these use the AHI (apnoea/hypopnoea index (apnoea/hypopnoea episodes per hour))

Answer 8

The diagnosis of OSAS requires at least five episodes of apnoea, hypopnoea, or both events per hour of sleep. The severity of OSAS is based on the number of apnoea/hypopnoea episodes per hour (apnoea-hypopnoea index [AHI]). * Mild: AHI 5–14 per hour. * Moderate: AHI 15–30 per hour. * Severe: AHI more than 30 per hour.

Question 9

What is the most effective therapy for treating obstructive sleep apnoea? What patient does NICE recommend it to?

Answer 9

CPAP - continuous positive airway pressure - keeps the airway open Nice recommends CPAP to patients with moderate or severe OSA Moderate: AHI 15–30 /hour. Severe: AHI > 30 /hour.

Question 10

In patients with mild OSA or with normal daytime alertness, what treatment can be used?

Answer 10

Mandibular advancement device - moves the lower jaw forward and helps to prevent snoring Used in mild OSA (AHI 5-15/hr)