Obstructive Sleep Apnoea

Question 1

Define obstructive sleep apnoea and obstructive sleep apnoea syndrome

Answer 1

• OSA = recurrent episodes of partial or complete upper airway obstruction during sleep, intermittent hypoxia and sleep fragmentation
• OSAS = manifests as excessive daytime sleepiness

Question 2

Describe the mechanism of OSAS

Answer 2

• decreased muscle tone results in pharyngeal narrowing
• causes a negative intra-thoracic pressure which causes arousal during sleep
• sleep disrupted (resulting in reduced QOL and sleepiness)
• BP surge (resulting in heart attacks and strokes)

Question 3

Describe how the airway of someone with OSA differs

Answer 3

• increased fat deposition/increased tonsil size
• decreased cross-sectional diameter of airway

Question 4

What are the symptoms of OSA?

Answer 4

• snorer
• witnessed apnoeas
• disruptive sleep (nocturia/choking/dry mouth/sweating)
• unrefreshed sleep
• daytime somnolence
• fatigue/low mood/poor concentration

Question 5

How do you assess a patient you suspect has OSA?

Answer 5

• history (+ partner history)
• weight/BMI
• BP
• neck circumference (increased risk >40cm)
• craniofacial appearance (retrognathia, micrognathia)
• tonsils
• nasal patency

Question 6

What questionnaire is used to measure daytime sleepiness?

Answer 6

Epworth sleepiness score

Question 7

What is the gold-standard investigation for OSAS?

Answer 7

Limited polysomnography:
- 5 channel home study
- O2 sats
- HR
- flow
- thoracic and abdominal effort
- position

Question 8

What are the advantages of a full PSG?

Answer 8

• ensures you are treating the correct patient
• accurate assessment of sleep efficiency
• sleep staging via EEG
• parasomnic activity measured - acting out dreams, sleep talking

Question 9

What investigations are used during the LPG to determine quality of sleep?

Answer 9

TOSCA (transcutaneous O2 satus and CO2 assessment)

Question 10

Define apnoea

Answer 10

• cessation or near cessation of airflow
• 4% O2 desaturation, lasting 10+ seconds

Question 11

Define hypopnoea

Answer 11

Reduction of airflow to a degree insufficient to meet the criteria of apnoea

Question 12

Define respiratory effort related arousals

Answer 12

Arousals associated with a change in airflow that does not meet the criteria for hypopnoea/apnoea

Question 13

How is the AHI and ODI calculated?

Answer 13

AHI (apnoea-hypopnoea index) = adding number of apnoeas and hypopnoeas and dividing by total sleep time in hours

ODI (oxygen desaturation index) = number of times per hour of sleep that SpO2 falls 4% or more from baseline

Question 14

What AHI results are indicative of OSA?

Answer 14

AHI = 15+ (OSA)
AHI = 16-30 (moderate OSA)
AHI = >30 (severe OSA)
* AHI = 5-15 + compatible symptoms can warrant a diagnosis

Question 15

Describe how you would manage OSAS

Answer 15

• aim: improve daytime sleepiness + QOL
• treat symptoms
• explain OSAS
• explain that weight loss and avoiding triggering factors eg. Alcohol/sedative medications can help
• treat underlying conditions (large tonsils, hypothyroidism, nasal obstruction)

Question 16

What is CPAP?

Answer 16

• continuous positive airway pressure
• a mask that lies over the nose and directs air into the throat to keep the airway open
• stops snoring and sleep fragmentation
• improves sleepiness during the day + QOL

Question 17

What is defined as compliance for CPAP?

Answer 17

> 4 hrs for >70 days

Question 18

When is MAD used?

Answer 18

• mandibular advancement device
• for mild-moderate OSAS unable to tolerate CPAP
• requires good dentition

Question 19

Describe a treatment for supine OSA

Answer 19

• sleep position trainer
• wear around the torso and it vibrates when the person is sleeping on their back
• takes weeks to change sleeping position

Question 20

What are the potential consequences of untreated OSAS?

Answer 20

• hypertension
• right heart strain
• CV disease + increased risk of CVA
• increased accidents at work/ poor concentration
• increased road traffic accident

Question 21

Describe the rules of OSAS and driving

Answer 21

• it is patient’s responsibility to contact DVLA about diagnosis of OSAS
• if OSA without daytime sleepiness, do not need to stop driving or contact DVLA unless previous history of vehicle crashes
• can hold category 1 license if compliant with treatment and daytime sleepiness improves (assessed every 3 years)