Obstructive Sleep Apnoea Flashcards
What is the definition of obstructive apnoea?
Recurrent episodes of partial or complete upper airway obstruction during sleep
- causes excessive daytime sleepiness
2 or more of the following symptoms indicate sleep apnoea.
Choking or gasping during sleep Recurrent awakenings from sleep Unrefreshing sleep Daytime fatigue Impaired concentration
What are the risk factors for sleep apnoea?
Male/post menopausal state Obese - 10% weight gain associated with six-fold increase risk of OSA Snorer Hypertensive Diabetic Increasing age Race Craniofacial anatomy Genetics Alcohol consumption Smoking
What are the forces being exerted on the throat at all times?
Promotion of airway collapse - negative pressure on inspiration - extralumenal positive pressure - fat deposition - small mandible Promotion of airway patency - pharyngeal dilator muscle contraction - lung volume (longitudinal traction)
What is the cause of sleep apnoea?
Imbalance of forces on the airway
- increase in forces promoting airway collapse
Describe the mechanism of obstructive sleep apnoea hypopnoea syndrome.
Pharyngeal narrowing -> negative thoracic pressure -> arousal
When the person wakes, their sleep is distrupted
- sleepiness
- reduced quality of life
- road accidents
When the person wakes, there is a blood pressure surge
- heart attacks
- strokes
What are the signs and symptoms of OSA?
Snoring Witnessed apnoeas Obesity Hypertension EDS Family history Non-restorative sleep
What are the four different types of investigations into sleep apnoea?
Type 1 - full attended overnight PSG
Type 2 - Full unattended PSG
Type 3 - at least 4 channels
Type 4 - one or two channels
What is the difference between apnoea and hypopnoea?
Apnoea - reduction in airflow of greater than 90% of the baseline for at least 10 seconds
Hypopnoea - reduction in airflow of greater than 30% of baseline for at least 10 seconds, associated with a greater than 3% desaturation from pre-event basline
What is the difference between central sleep apnoea and obstructive sleep apnoea?
Central sleep apnoea is a disorder where your breathing rapidly stops and starts during sleep
Obstructive sleep apnoea is when you can’t breathe normally because of upper airway obstruction
What is Cheyne-Stokes respiration?
An abnormal pattern of breathing characterised by progressively deeper and sometimes faster breathing, floowed by a gradual decrease that results in a temporary stop in breathing.
How is sleep apnoea treated?
CPAP - continuous positive airway pressure
Weight reduction
Mandibular advancement splints
Surgery
How does CPAP work?
A mask is strapped over the nose (and mouth) of the patient.
This mask is attached to a machine that blows air into the tube
The air being blown in during the night keeps a higher pressure inside the upper airway than outside it - and so it remains open
What are the health benefits of CPAP use?
Improves
- sleepiness
- cognition
- health status
- driving
- blood pressure (therefore reduces risk of stroke)
How does weight reduction help obstructive sleep apnoea?
A 20% reduction in weight can result in an almost 50% reduction in the apnoea-hypopnoea index.
If a person weighs less, then there is less weight pressing on the upper airway, and so it is less likely to close
