Sleep apnoea and neuromuscular respiratory failure Flashcards
what is obstructive sleep apnoea syndrome
Recurrent episodes of upper airway obstruction leading to apnoea (temporary cessation of breathing) during sleep - loud snoring
define apnoea
temporary cessation of breathing for at least 10 seconds
what are some daytime effects of sleep apnoea syndrome
Daytime somnolence /sleepiness Poor daytime concentration
which age group commonly have sleep apnoea
elderly
what 3 things combined cause repeated obstruction of the airways in a patient
muscle relaxation narrow pharynx obesity
what other health conditions is OSAS associated with? (3)
hypertension stroke heart disease
public health risk of apnoea?
road traffic accidents
how is OSAS diagnosed? (4)
Clinical history and examination Epworth Questionnaire Overnight sleep study
what things are looked at in a polysomnography sleep study? (3)
pulse oximetry - O2 saturation oronasal flow ECG Electromyography (EMG) chest - diagnostic procedure to assess muscle and the nerve cell function abdominal wall movement during sleep
what is the Epworth sleeping scale?
a scale where patients have to grade how likely they are to fall asleep in certain situations from 0= would never doze to 3= high chance of dozing
There are 8 situations. Some for example are:-
- Sitting and reading
- Watching TV
- sitting inactive in a public place ie cinema
- In a car while stopped for a few minutes in the traffic
what is an abnormal level on the Epworth chart?
>11
What is recorded in limited sleep studies
pick up strain in chest/ abdomen if they expand/move with bands video recordings pulse oximetry - O2 saturation oronasal flow
what is the gold standard OSAS study
polysomnography
what is used to measure the severity of sleep apnoea
AHI- Apnea–Hypopnea Index
how is OSAS treated/managed?
Mandibular repositioning splint - device worn in the mouth Continuous positive airways pressure (CPAP) - ie O2 via a nasal mask - recommended for moderate to severe sleep apnoea Identify exacerbating factors - weight, smoking, alcohol
exacerbating factors of OSAS (3)
weight gain/obesity alcohol endocrine disorders e.g. hypothyroidism - enlargement of the tongue or disruption of the muscles that control the upper airway. acromegaly - overreaction of pituitary gland - osseous and soft-tissue changes surrounding the upper airway - narrowing and subsequent collapse during sleep.
which is less intrusive? CPAP ro mandibular repositioning splint?
mandibular repositioning splint
what is CPAP?
a mask worn at night which is connected to a machine that blows air into the throat and this creates low pressure that keeps smooth muscle apart to prevent obstruction
what is mandibular repositioning splint
a mouthguard that brings the tongue forward
what is chronic ventilatory failure?
not enough oxygen passes from your lungs into your blood condition is associated with hypercapnia and low O2 for it to be chronic need to have normal blood pH and elevated bicarbonate
General causes of chronic ventilatory failure? (4)
Airways disease Chest wall abnormalities Respiratory muscle weakness Central hypoventilation syndrome - autonomic nervous system doesn’t control breathing properly
examples of airway diseases that lead to chronic ventilatory failure
COPD bronchiectasis OSA
typical symptoms of chronic ventilatory failure (6)
Breathlessness Orthopnoea ankle swelling - due to complications with chronic condition like pulmonary hypertension or cor pulmonale Morning headache - rise in CO2 - widening of blood vessels in the brain - more pressure in CSF Recurrent chest infections Disturbed sleep
what is orthopnoea
shortness of breath whilst lying flat
what 2 things should you really look out for in examination: chronic ventilatory failure
paradoxical abdominal wall motion in suspected neuromuscular disease - bilateral diaphragmatic paralysis causes abdominal wall to move inwards instead of out on inspiration Ankle oedema - sign of pulmonary hypertension or cor pulmonale
how do we investigate neuromuscular disease? (2)
lung function assessment of hypoventilation
treatment of neuromuscular disease? (2)
Non Invasive Ventilation (NIV) - mask on the face (different to CPAP) Oxygen therapy
narrow pharynx can be due to?
genetic inheritance
what does repeated closure of upper airway cause?
snoring oxygen desaturation apnoea and hypopnoeas
what is a hypopnoea
only partial blockage of the airway
what is snoring caused by at a physiological level?
tissues vibrating together
what is microarousal?
when your brain senses that you’re not breathing so it goes from a deep to light sleep and sometimes you even wake up
approx prevelence of sleep apnoea in adult men and women?
men- 2% women- 1%
what is pulse oximetery
monitoring the oxygen saturation of a patient’s blood and changes in blood volume in the skin whilst they sleep
what does a full polysomnography test include?
recorded in hospital: - brain waves - oxygen level in your blood - heart rate and breathing - eye and leg movements
limited sleep studies
home tests limited scope can include abdominal/thoracic bands to see movement/expansion nasal flow
Electromyography (EMG) shows?
skeletal muscle movement
what is narcolepsy
falling asleep uncontrollably in any situation very rare, can be familial
clinical features of narcolepsy
cataplexy- collapsing after strong emotion or laughter excessive daytime somnolence - need/ desire to sleep sleep hallucinations or paralysis
how is chronic respiratory failure linked with neuromuscular disease?
Brain sends signals to the respiratory muscles so if there is interference with this then it can cause respiratory muscle weakness and therefore insufficient ventilation or nocturnal hypoventilation
how is blood pH normal but with elevated bicarbonate in chronic ventilatory failure?
the kidney’s usually get rid of bicarbonate but in chronic V.F the kidneys retain it as a way of balancing the elevated PCO2 levels that occur.
acute ventilatory failure
rapid onset pH decreases because the kidney’s haven’t had time to react and retain bicarbonate
what is the desaturation rate for mild OSA
5-15 desaturations per hour ie no. of times per hour of sleep that the blood’s O2 level drops by a certain degree from baseline
what is the desaturation rate for normal OSA
0-5 per hour no. of times per hour of sleep that the blood’s O2 level drops by a certain degree from baseline
what is the desaturation rate for moderate OSA
15-30 per hour no. of times per hour of sleep that the blood’s O2 level drops by a certain degree from baseline
what is the desaturation rate for severe OSA
>30 per hour no. of times per hour of sleep that the blood’s O2 level drops by a certain degree from baseline
what is the link with neuromuscular disease and sleep apnoea?
Specific characteristics of neuromuscular disorders, such as pharyngeal neuropathy or weakness, macroglossia (enlarged tongue) or low lung volumes, predispose patients to the development of obstructive events ie OSAS
