Obstructive Sleep Apnoea

Question 1

What is obstructive sleep apnoea (OSA)?

Answer 1

Sleep-disorder breathing due to upper airway collapse leading to obstructive apnoea and hypopnoeas with desaturation.

Question 2

Most common people getting OSA.

Answer 2

Middle aged overweight men.

Question 3

Risk factors of OSA.

Answer 3

Age

Menopause

Obesity

Endocrine conditions such as acromegaly and hypothyroidism.

Question 4

When might OSA occur in children?

Answer 4

Enlarged tonsils of trisomy 21.

Question 5

Pathophysiology of OSA.

Answer 5

During sleep (especially REM) respiratory muscle activity is reduced. In REM only diaphragm is working.

Airway at back of the throat is sucked close (e.g. due to excessive neck fat) when breathing in during sleep in OSA.

Genioglossus and palatal muscles which keep the upper airway open when we are awake become hypotonic.

If there is complete occlusion this causes apnoea.

The apnoea leads to hypoxia and increasingly strenuous respiratory efforts.

The combination of hypoxia and effort to overcome obstruction wakes the patient up.

The awakening is so brief it’s not noticeable for the patient. This occurs throughout the night.

Question 6

Symptoms of OSA.

Answer 6

Most common highest up…

Loud snoring

Daytime sleepiness

Unrefreshed sleep

Restless sleep

Morning headache

Nocturnal choking

Reduced libido

Mroning drunkenness

Ankle swelling

Question 7

Causes of OSA.

Answer 7

Encroachment of pharynx such as obesity (fatty infiltration of pharyngeal tissues), large tonsils, craniofacial abnormalities and extra submucosal tissue (myxoedema)

Nasal obstruction like nasal deformities, rhinits, polyps and adenoids.

Respiratory depressant drugs like alcohol, sedatives, strong analgesics

Neuromuscular disease

Question 8

How to diagnose OSA.

Answer 8

Relatives provide a snore-silence-snore cycle.

Symptom presentation such as poor concentration and waking up unrefreshed.

Patients are asked by Epworth Sleepiness Scale.

STOP BANG tool can be used to screen and differentiate from simple snoring.

Question 9

Once the diagnosis is suspected, what further investigations should be done?

Answer 9

Overnight pulse oximetry, monitoring pulse and O2 levels done at home.

Nocturnal polygraphy can also be done.

Question 10

What is the Epworth Sleepiness Scale?

Answer 10

A measure of excessive daytime sleepiness.

Broken into a chance of dozing from 0-3 when…

Sitting and reading,

Watching TV,

Sitting inactive in a public place,

Lying down to rest in the afternoon,

Sitting and talking to someone,

Sitting quietly after lunch,

In a car, while stopped for a few minutes in traffic.

Question 11

What is a normal Epworth Sleepiness score?

Answer 11

<9

>9 might suggest OSA.

Question 12

Explain the STOP BANG tool

Answer 12

Snoring?

Tiredness?

Observed apnoeas

Pressure (high BP)?

BMI? (>35)

Age? (>50)

Neck size? (> 43 cm male, 41 cm female)

Gender? (male)

Question 13

Explain sleep-disordered investigation by overnight pulse oximetry, pulse monitoring and O2 levels.

Answer 13

Oximetry shows desaturations in a cyclical manner if OSA is suspected. The pattern is called sawtooth.

The oximetry desaturation index (ODI) measures the number of desaturations per hour.

This can determine the severity of sleep apnoea.

Question 14

Overnight oximetry cannot distinguish between central and obstructive sleep apnoea.

How is this done?

Answer 14

By nocturnal polygraphy.

Question 15

Explain nocturnal polygraphy.

Answer 15

Measures body posture, movements, breathing rate, EEG, and pulse oximetry.

This is only done when diagnosis is uncertain.

Question 16

How is severity of OSA defined?

Answer 16

By apnoea-hypopnea index (AHI)

Question 17

Explain AHI.

Answer 17

Number of episodes of apnoea or hypopnea per hour.

<5 is normal

5-15 is mild OSA

15-30 is moderate OSA

>30 is severe OSA

Question 18

What is treatment based on in OSA?

Answer 18

On symptoms and quality of life not on severity in sleep studies.

Question 19

Simple approach management of OSA.

Answer 19

Weight loss

Sleep decubitus instead of supine.

Avoid or reduce alcohol intake.

Question 20

Treatment of OSA for snorers and mild OSA.

Answer 20

Mandibular advancement devices

Pharyngeal surgery as last resort.

Question 21

Treatment of significant OSA.

Answer 21

Nasal CPAP

Gastroplasty/bypass

Very rarely tracheostomy

Question 22

Treatment of severe OSA and CO2 retention.

Answer 22

NIV prior to CPAP if acidotic.

Compensated CO2 may reverse with CPAP alone.

Question 23

What is CPAP?

Answer 23

Usually a nasal mask but can use mouth/nose masks as well.

Upper airways is splinted open with approx 10 cm H2O pressure.

This prevents the airway from collapsing.

Also prevents sleep fragmentation and ultimately daytime somnolence.

It also opens collapsed alveoli and improves V/Q mismatch.

Question 24

Treatment ladder of OSA

Answer 24

Lifestyle changes with weight loss, sleeping on the side instead of back and avoiding or reducing alcohol (respiratory depressant).

If this is not enough and the symptoms and QOL are severly affected then you might want to move on to CPAP.

If this is still not enough or the person is not tolerating CPAP then surgery such as uvulopalatopharyngoplasty (UPPP) can be done. This is however rare.

Question 25

Complications of OSA.

Answer 25

Can increase the risk of MI and stroke.