Sleep Apnoea And Neuromuscular Respiratory Failure

Question 1

Describe sleep apnoea syndrome.

Answer 1

Recurrent episodes of airway obstruction leading to apnea during the night
(Obstruction is in the posterior pharynx)

Question 2

What is OSAS associated with?

Answer 2

Heavy snoring
Day time somnolence / sleepiness
Day time lack of concentration
Hypertension
Increased risk of stroke
Increased risk of heart disease

Question 3

What are the 3 main pathophysiological factors which cause repeated closure of the upper airways leading to apnea?

Answer 3

Muscle relaxation
Narrow pharynx’
Obesity

Question 4

What is the difference between apnea and hypapnea?

Answer 4

Apnea is when the obstruction lasts for at least 10 seconds

Hypapnea is when the obstruction is partial and incomplete

Question 5

What tests are carried out in the diagnosis of OSAS?

Answer 5

Clinical history and examination
Epworth questionaire
Overnight sleep study: full polysomnography, pulse oximetry, limited sleep studies

Question 6

In the diagnosis of OSAS, what is involved in the full polysomnography?

Answer 6

EEC, EMG, EOG,
orsonasal flow, thoracoabdominal flow,
audiovisual recording, body position and oximetry,

Question 7

How is the severity of OSAS scored?

Answer 7

It is based on the desaturation rate/ apnoea hypoxia level

0-5 = normal
5-15 = mild
15-30 = moderate
>30 = severe

Question 8

What is the treatment for OSAS?

Answer 8

Treat the exacerbating factors I.e. loose weight, avoid alcohol, diagnose and treat underlying neurological or endocrine disease.
Continuous positive airway pressure (CPAP)
Mandibular repositioning splint

Question 9

What are the clinical features of narcolepsy?

Answer 9

Cataplexy
Excessive day time somnolence
Hypnagogic hallucination
Sleep paralysis

Question 10

What is the treatment for narcolepsy?

Answer 10

Modafinil (stimulant)
Clomipramine (for cataplexy)
Sodium oxybate

Question 11

What are the pathological features of chronic ventilators failure?

Answer 11

Elevated PCO2 >6.0kPa
P02 < 8 kPa
Normal blood pH
Elevated bicarbonate

Question 12

What are the causes of chronic ventilator failure?

Answer 12

Most common is COPD and obesity hypoventilation syndrome
Chest wall abnormalities I.e. kyphoscoliosis
Respiratory muscle weakness I.e. motor neurons disease or muscular dystrophy

Question 13

What are the symptoms of chronic ventilator failure?

Answer 13

Breathlessness
Orthopnoea
Ankle swelling
Morning headache
Recurrent chest infection
Disturbed sleep

Question 14

In chronic ventilator failure, what is found on clinical examination?

Answer 14

It depends on the underlying disease
Paradoxical movement of abdomen wall in suspected neuromuscular disease
Ankle oedema in patient with hypoxia/cor pulmonale

Question 15

What is the treatment for chronic ventilator failure?

Answer 15

Domicillary non invasive ventilation (biPAP) - higher pressure than CPAP
Oxygen therapy
Tracheostomy ventilation (rarely used now)

Question 16

What is the normal sleeping hours/patterns for a;

1) 6 month?
2) 2 year old?
3) new born?

Answer 16

1) 14-16 hours with 1-2 daytime naps
2) 12 hours with 1 daytime nap
2) 16-18 hours, sleep/wake 3-4 hour cycles

Question 17

How can you asses sleep in children?

Answer 17

Polysomnography 
Direct behavioral observation
Time lapse video
Movement sensor in cot mattress
02/c02 monitoring

Question 18

What are causes of excessive sleepiness in children?

Answer 18

Insufficient sleep
Narcolepsy
Obstructive sleep apnoea syndrome

Question 19

How can OSAS cause death in children?

Answer 19

Failure to thrive
Neurocognitive defects
Systemic hypertension
For pulmonale

Question 20

What are the treatments for OSAS in children?

Answer 20

Adenotonsillectomy
Weight loss
CPAP
Avoid environmental tobacco smoke

Question 21

What are respiratory disorders associated with sleep apnoea in children?

Answer 21

Chronic neonatal lung disease
Cystic fibrosis
Asthma

Question 22

What are neurological disorders that are associated with sleep apnoea in children?

Answer 22

Cerebral palsy
Down’s syndrome
Prayer willi syndrome
Neuromuscular disease i.e. duchesses muscular dystrophy

Question 23

what sleep pattern/condition if on in:

a) down syndrome
b) Cystic fibrosis
c) chronic neonatal lung disease
d) prader willi syndrome

Answer 23

a) OSAS
b) less REM sleep/more awakenings
c) hyperaemia during REM sleep
d) excessive daytime somnolenece, they may be hypertonic

Question 24

what is the pathophysiology of chronic ventilatory failure?

Answer 24

Pa02 < 8kPa
PaC02 >6kPa
normal blood PH
elevated bicarbonate

Question 25

what are the symptoms of chronic ventillatory failure?

Answer 25

dyspnoea
orthopnoea
morning headache
recurrent chest infections
ankle oedema
disturbed sleep

Question 26

on examination of chronic ventillatory failure, what would you look for in suspected neuromuscular disease?

Answer 26

paradoxical abdominal wall motion

Question 27

how can chronic ventillatory failure cause ankle oedema?

Answer 27

chronic ventillatory failure due to hypoxic cor pulmonale causes hypertrophy of right ventricle resulting in inefficient pumping of the right heart so blood backs up in the systemic circulation.

Question 28

what are the investigation carried out for chronic ventillatory failure?

Answer 28

Lung function:

• nasal sniff inspiratory pressure
• lying and standing vital capacity

Assessment of hypoventilation:

• early morning ABG
• overnight oximetry
• transcutaneous C02 monitoring
• fluoroscopic screening of diaphragm