Obstructive Sleep Apnoea

Question 1

Define obstructive sleep apnoea syndrome.

Answer 1

Recurrent episodes of partial or complete upper airway obstruction during sleep

Question 2

What are the diagnostic criteria for OSAS? (7)

Answer 2

Apnoea-hypopnoea index (AHI): 5+

Excessive day time fatigue

2+ of the following:

• Choking/gasping during sleep
• Recurrent awakening
• Unrefreshing sleep
• Daytime fatigue
• Impaired concentration

Question 3

What is the apnoea-hypopnoea index (AHI)?

What value is diagnostic of OSAS?

Answer 3

Def. “Number of apnoea and hypopnoea events per hour of sleep”

AHI for OSAS diagnosis: 5+

Question 4

List 8 risk factors for OSAS.

Answer 4

Male
Post-menopausal women
Age
Race
Snoring
Lifestyle factors (including smoking, alcohol, obesity)
Co-morbidities
Family history

Question 5

Describe the pathophysiology of OSAS. (4)

Answer 5

1. Pharyngeal narrowing leads to negative thoracic pressure
   a. This causes sudden arousal
2. Sudden arousal has two main effects:
   a. Sleep disruption
   b. Blood pressure surge
3. Sleep disruption causes:
   a. Excessive daytime sleepiness
   b. Reduced quality of life
   c. Increased risk of RTCs
4. Blood pressure surges cause:
   a. Increased risk of heart attack
   b. Increased risk of stroke

Question 6

List 6 symptoms of OSAS.

Answer 6

Snoring
Witness apnoeas (e.g. by partner)
Obesity
Non-restorative sleep
Apnoea events
Hypopnoea events

Question 7

Define an apnoea event.

Answer 7

At least a 90% reduction in airflow for at least 10 seconds, associated with blood desaturation

Question 8

Define a hypopnoea event.

Answer 8

At least a 30% reduction in airflow for at least 10 seconds, associated with at least 3% oxygen desaturation

Question 9

List 6 complications of OSAS.

HINT: there are 2 main categories.

Answer 9

NEUROLOGICAL CONSEQUENCES:
Motor vehicle accidents
Occupational accidents

CARDIOVASCULAR CONSEQUENCES:
Hypertension
CAD and MI
Stroke
Congestive heart failure

Question 10

What is the main investigation done for OSAS?

Answer 10

Sleep studies

Question 11

Describe 4 types of sleep study.

Answer 11

Type 1 - full attended overnight polysomnography (PSG)

Type 2 - full, unattended polysomnography (PSG)

Type 3 - sleep study with at least 4 channels

Type 4 - sleep study with 1 or 2 channels

Question 12

What are the 3 types of sleep apnoea?

Answer 12

Obstructive sleep apnoea
Central apnoea
Cheyne-Stokes respiration

Question 13

What causes central apnoea?

Answer 13

Lack of respiratory drive from CNS

Question 14

What is Cheyne-Stokes respiration?

Describe its features. (3)

Answer 14

Abnormal breathing pattern:

1. Progressively deeper and faster breathing
2. Gradual decrease in breathing, resulting in apnoea
3. Repeats in cycles, each one lasting 30 seconds - 2 minutes

Question 15

How do you treat OSAS? (5)

Answer 15

Continuous positive airway pressure (CPAP)
Weight loss
Mandibular advancement splints
Surgery
Adjuvant medical treatment

Question 16

How does continuous positive airway pressure (CPAP) work? (3)

Answer 16

Facial/nasal mask administers continuous airflow to patient

This creates a constant positive airway pressure

Therefore airways cannot fall closed

Question 17

List 3 indications for using mandibular advancement splints.

Answer 17

Snoring
Mild OSAS
Intolerance to CPAP

Question 18

List 7 examples of surgery to improve OSAS.

Answer 18

Bariatric surgery (for weight loss)
Tracheostomy
Jaw advancement surgery
Palatal surgery
Palatal implants
Adenotonsillectomy
Laser surgery

Question 19

Which drug might be used in adjuvant therapy for OSAS?

How does it work?

Answer 19

Modafinil

Decreases fatigue