Obstructive Sleep Apnoea

Question 1

What is obstructive sleep apnoea?

Answer 1

A disease characterised by recurrent prolapse of the pharyngeal airway and apnoea (cessation of airflow for> 10 s) during sleep, followed by arousal from sleep. Also known as Pickwickian syndrome.

Question 2

What is the cause/ risk factors for OSA?

Answer 2

1. Occurs due to narrowing of the upper airways because of the collapse of soft tissues of the pharynx due to decreased tone of the pharyngeal dilators during sleep.  
2. Associated with: 
   - Weight gain 
   - Smoking 
   - Alcohol 
   - Sedative use 
   - Enlarged tonsils and adenoids in children 
   - Macroglossia- unusually large tongue (hypothyroidism, amyloidosis and acromegaly) 
   - Marfan’s syndrome 
   - Craniofacial abnormalities 
   - Family history
   - Hypothyroidism

Question 3

What presenting symptoms of OSA can be found in the history?

Answer 3

• Excessive daytime sleepiness/drowsiness (somnolence) 
• Unrefreshing or restless sleep 
• Morning headaches 
• Dry mouth 
• Difficulty concentration 
• Irritability and mood changes 
• Partner reporting snoring, nocturnal apnoeic episodes or nocturnal choking 
• Compensated respiratory acidosis 
• Other causes of respiratory acidosis: COPD, opiates, atelectasis 

Question 4

What signs of OSA can be found on physical examination?

Answer 4

• Large tongue 
• Enlarged tonsils 
• Long or thick uvula 
• Retrognathia (pulled back jaws) 
• Neck circumference 
  *More than 42 cm in males 
  *More than 40 cm in females 
• Obesity 
• Hypertension 

Question 5

What differentials may be associated with OSA?

Answer 5

1. Absence seizure (where you lose awareness of your surroundings for a short time)
2. Narcolepsy (sleep disorder that makes people very drowsy during the day)
3. Cataplexy - sudden physical collapse with intact consciousness, stimulated by strong emotion or laughter 

Question 6

What investigations are used to diagnose/ monitor OSA?

Answer 6

1. Assessment of sleepiness: video recording of episodes
2. Epworth sleepiness scale (questionnaire completed by patient/partner) (0-6 is normal, 9-24 points is abnormal sleepiness) 
3. Multiple sleep latency test- MSLT (measures how quickly one falls asleep, the sleepier you are the faster you should fall asleep) 
4. Sleep Study/polysomnography (PSG) - diagnostic 
   - Ranges from monitoring pulse oximetry at night, to full polysomnography (measures respiratory airflow, thoracoabdominal movement, EEG, ECG, capnography, snoring and pulse oximetry 
   DIAGNOSIS IF APNOEA-HYPOPNOEA INDEX (AHI) > 15 episodes/hour 
5. Portable multichannel sleep tests 
   - Used for patients with a higher probability of OSA 
   - DIAGNOSIS IF Respiratory-event index (REI) > 15 episodes/hour 
6. Awake fibreoptic endoscopy - performed to exclude nasal polyps/laryngeal/pharyngeal tumours 
7. Bloods 
   - TFTs - thyroid cancer could be pressing on and obstructing airways 
8. ABG - compensated respiratory acidosis 

Question 7

How is OSA managed?

Answer 7

• Weight loss 
• Smoking cessation
• Alcohol avoidance in the evening
• Continuous positive airway pressure (CPAP) is first line for moderate or severe OSAHS 
• Intra-oral devices (e.g. mandibular advancement) may be used if CPAP is not tolerated or for patients with mild OSAHS where there is no daytime sleepiness 
• the DVLA should be informed if OSAHS is causing excessive daytime sleepiness 
• limited evidence to support use of pharmacological agents 

Question 8

What complications can arise from OSA?

Answer 8

• Coronary artery disease 
• Impaired glucose metabolism
• Heart attacks 
• Heart failure  
• Strokes 
• Pulmonary hypertension
• Type II respiratory failure

Question 9

Describe the prognosis of OSA

Answer 9

Very good 

Question 10

Describe the epidemiology of OSA

Answer 10

• COMMON 
• 5-20% of men > 35 yrs 
• 2-5% of women > 35 yrs 
• Prevalence increases with age