Sleep apnoea and Neuromuscular Respiratory disorders

Question 1

Describe presentation of sleep apnoea.

Answer 1

Heavy snoring, typically unrefreshing sleep. Daytime somnolence/sleepiness. Poor daytime concentration.

Question 2

Describe consequences of untreated sleep apnoea.

Answer 2

Why OSAS is important - impaired quality of life, marital dysharmony, increased risk of RTA’s, associated with hypertension, increased risk of stroke and probably increased risk of heart disease.

Question 3

Describe management options for sleep apnoea

Answer 3

Treatment
- identify exacerbating factors such as weight reduction
- avoidance of alcohol
- diagnose and treat endocrine disorders
- Continuous positive airways pressure (CPAP)
- Mandibular repositioning splint.

Question 4

Describe investigations used to diagnose sleep apnoea.

Answer 4

Diagnosis of sleep apnoea -
- clinical history and examination,
- epworth questionnaire
- Also overnight sleep study - pulse oximetry, limited sleep studies, full polysomnography.

Question 5

Describe Pathophysiology of sleep apnoea.

Answer 5

Muscle relaxation, narrow pharynx or obesity can cause repeated closure of upper airways which in turn can cause snoring, oxygen desaturation and apnoeas and hypoaponeas.

Question 6

Describe clinical features of narcolepsy

Answer 6

Clinical features of narcolepsy
- cataplexy
- excessive daytime somnolence
- hypnagogic/hynopmpic hallucinations
- sleep paralysis.

Question 7

Describe investigations for narcolepsy.

Answer 7

Investigations of narcolepsy - PSG, MSLT and low CSF orexin.

Question 8

Describe treatment for narcolepsy.

Answer 8

Treatment for narcolepsy - modafinil, dexamphetamine, venlafaxine (for cataplexy) and sodium oxybate.

Question 9

Describe the difference between acute and chronic ventilatory failure and how they can be distinguished

Answer 9

Chronic ventilatory failure - elevated pCO2 (> 6.0 kPA). pO2 < 8kPA, normal blood pH. Elevated bicarbonate.

Acute ventilatory failure - acute rises in pCO2 and low blood pH.

Henderson Hasselbach equation can be used to distinguish between acute and chronic ventilatory failure.

Question 10

Describe aetiology of chronic ventilatory failure.

Answer 10

• Airways disease - COPD and bronchiectasis.
• Chest wall abnormalities - kyphoscoliosis.
• Respiratory muscle weakness - motor neurone disease, muscular dystrophy, glycogen storage disease. - Central hypoventilation - obesity hypoventilation syndrome, congenital central hypoventilation syndrome.

Question 11

Describe symptoms of chronic ventilatory failure.

Answer 11

Typical symptoms -
breathlessness,
orthopnoea,
ankle swelling,
morning headache,
recurrent chest infections,
disturbed sleep.

Question 12

Describe investigations for chronic ventilatory failure.

Answer 12

• lung function tests - lying and standing VC, mouth pressures/SNIP.
• Assessment of hypoventilation - Early morning ABG, Overnight oximetry, transcutaneous CO2 monitoring.

Question 13

Treatment for chronic ventilatory failure.

Answer 13

Treatment -
- domicillary non invasive ventilation (NIV),
- oxygen therapy, (t-IPPV).