Sleep Apnoea and Narcolepsy Flashcards
What is obstructive sleep apnoea syndrome?
Recurrent episodes of upper airway obstruction leading to apnoea during sleep and is usually associated with snoring
What are the effects of OSAS on patients?
Typically unrefreshing sleep, daytime sleepiness and poor daytime concentration
What does somnolence mean?
Sleepiness
Explain the pathophysiology of OSAS?
Muscle relaxation, narrow pharynx and obesity can cause repeated closure of upper airway
This causes apnoeas and hypopnoeas which causes frequent microarousals
What is the outcome of repeated closure of upper airway?
Snoring
O2 desaturation
Apnoea and hypopnoea
Why is OSAS important?
Impaired QoL
Increased risk of road traffic accidents
Risk of hypertension, stroke and heart disease
How is OSAS diagnosed?
Clinical history and examination
Epworth questionnaire
Overnight sleep study
Explain the Epworth questionnaire?
Patients ranks questions 0-3 from would never doze to high chance of dozing
What is overnight oximetry measuring?
O2 saturation and pulse rate
What would oximetry look like if patient has sleep apnoea?
Repetitive desaturation
Pulse rate follows saturation
What equipment is in a limited sleep study (embletta)?
Thora movement, oximetry and nasal canula
What is central apnoea?
Less common
Not due to obstruction
Is lack of respiratory drive from brainstem
What is filled in when carrying out limited sleep study?
Sleep study report
Analysed by technician or computer
What is measured in a polysomnography?
Oronasal airflow, thorax movement, oximetry, body position, EEG, Audiovisual recording, EOG, EMG an ECG
What is an EEG?
Checks brain waves during the night - can tell if patient is actually asleep
What is an EOG?
AN electrooculogram measuring eye movement
What is EMG measuring?
Peripheral muscle
What is filled out after a polysomnography?
PSG report
Contains a hypnogram which shows the stage of sleep
What is the REM stage of sleep?
Dreaming stage so get rapid eye movements
What is stage 1-3 of sleep?
1and 2 are asleep and 3 is deep
What is W stage of sleep?
Wakefulness
How is OSA severity measured?
Desaturation rate/AHI
0-5 is normal
5-15 is mild
15-30 is moderate
>30 is severe
What is AHI?
Total no. of apnoeas in sleep divided by hours of sleep
What is the treatment for sleep apnoea?
Identify exacerbating factors
Continuous positive airways pressure (CPAM)
Mandibular repositioning splint
What are some exacerbation factors that can cause sleep apnoea?
Overweight
Alcohol
Endocrine disorder
Explain the mechanism of CPAM treatment?
Creates positive pressure so tissues in mouth don’t get stuck together in inspiration
How does mandibular repositioning splint help sleep apnoea?
Advance lower jaw forward so tongue is forward and creates more space at back of throat
Describe driving rules and sleep apnoea?
Advice patient to not drive or restrict driving
Inform DVLA
Once satisfactory treated should be allowed to drive
What is narcolepsy?
Rare long-term brain condition that causes a person to suddenly fall asleep at inappropriate times
Usually presents at younger age then apnoeas
What is narcolepsy associated with?
Can be familial
Associated with HLA types
Explain the clinical features of narcolepsy?
Cataplexy, excessive daytime sleepiness, hypnopompic hallucination and sleep paralysis
What is cataplexy?
Suddenly collapse during day and looks asleep
Person is kind of aware
Sudden muscle weakness
What investigations are used to diagnose narcolepsy?
Polysomnography
MSLT
Low CSF orexin tested by lumbar puncture
Explain MSLT investigation?
Multiple sleep latency test
Patient asked to sleep in dark room and time to get to sleep is measured
Under 6 mins is a sign
Explain the treatment of narcolepsy?
Modafinil
Dexamphetamine
Venlafaxine
Sodium Oxybate
Describe chronic ventilatory failure
Elevated pCO2 and pO2 is less than 8kPA
Type 2 resp. failure
Normal blood pH
Elevated bicarbonate
What are the causes of chronic ventilatory failure?
Airway disease, Chest well abnormalities, Respiratory muscle weakness, and central hypoventilation
What is airways diseases that cause chronic ventilatory failure?
COPD and bronchiectasis
What is a chest wall abnormality that cause chronic ventilatory failure?
Kyphoscoliosis
What are respiratory muscle weakness diseases that cause chronic ventilatory failure?
Motor neuron disease (ALS), muscular dystrophy and glycogen storage disease
What are central hypoventilation diseases that can cause chronic ventilatory failure?
Obesity hypoventilation syndrome and congenital central hypoventilation syndrome
What are typical symptoms of chronic ventilatory failure?
Breathlessness, orthopnoea, ankle swelling, morning headache, recurrent chest infection and disturbed sleep
Explain the term orthopnoea?
Breathlessness lying flat
Usually with muscular condition
What are some examination findings for chronic ventilatory failure?
Reflects underlying disease
Paradoxical abdominal wall motion in suspected neuromuscular disease
Ankle oedema
Explain paradoxical abdominal wall motion
Weakness of diaphragm
Wont contract properly so diaphragm drawn up
Chest wall then moves down
Opposite to normal
What investigations are done to diagnose neuromuscular disease?
Lung function
Assessment of hypoventilation
Fluoroscopic screening of diaphragm
What happens to FEV1 and FVC, and mouth pressure in neuromuscular disease?
FEV1 and FVC is reduced but ratio is higher as restrictive
Mouth pressure on inspiration and expiration is reduced
Explain the treatment for chronic ventilatory failure?
Domiciliary non invasive ventilation
O2 therapy
Tracheoscopy ventilation - 24hr
Not curable
