Obstructive sleep apnoea Flashcards
What is the definition of obstructive sleep apnoea?
Recurrent episodes of partial or complete upper (pharyngeal) airway obstruction during sleep, intermittent hypoxia and sleep fragmentation
How does obstructive sleep apnoea syndrome manifest?
As excessive daytime sleepiness
Explain the mechanism of obstructive sleep apnoea
- Pharyngeal narrowing
- Negative thoracic pressure
- Arousal from sleep
- Blood pressure surge (heart attack and stroke risk) and sleep disruption (sleepiness, reduced quality of life and risk of RTAs)
Describe the epidemiology of sleep apnoea
- Men 2-3 >premenopausal women
- Average age of incidence 40-50 years
- Incidence is increasing with the obesity epidemic
- COPD overlap is estimated in 1% of adults
What are the symptoms of obstructive sleep apnoea?
- snorer
- witnessed apnoeas
- Disruptive sleep - nocturne/choking/dry mouth/ sweating
- Unrefreshed sleep
- Daytime somnolence
- Fatigue/low mood/poor concentration
What clinical examinations should be carried out in someone with a suspected sleep apnoea?
- Weight
- BMI
- BP
- Neck circumference
- Craniofacial appearance (retrognathia, micrognathia)
- Tonsils
- Nasal patency
What can be used to asses daytime sleepiness?
- Epworth sleepiness score
- The STOP-BANG questionnaire
- The Berlin questionnaire
What are the available investigations for sleep apnoea?
- Limited polysomnography
- Full polysomnography
- Transcutaneous oxygen saturations and carbon dioxide assessment
What is measured in a limited polysomnography?
- Oxygen saturations
- heart rate
- Flow
- Thoracic and abdominal effort
- Position
What are the investigations of a full polysomnogrpahy?
- EEG - sleep staging
- Video
- Audio
- Thoracic and abdominal bands
- Position
- Flow
- Oxygen saturations
- Limb leads
- Snore
What are the advantages of a full polysomnography over a limited polysomnography?
- Correct patient
- Accurate sleep assessment of sleep efficiency
- Sleep staging via EEG
- Parasomnic activity- acting out dreams, sleep talking
What is apnoea in regards to the results of sleep studies?
- The cessation, or near cessation, of airflow
* 4% oxygen desaturation, lasting >/10 seconds
What is hypopnea in regards to the results of a sleep study?
•Reduction of airflow to a degree insufficient to meet the criteria for an apnoea
What are respiratory effort related arousals?
Arousals associated with a change in airflow that does not meet the criteria for apnoea or hypopnoea
How is the apnoea-hypopnea index calculated?
Adding the number of apnoeas and hypopnoeas and dividing by the total sleep time (in hours)
What is the oxygen desaturation index?
The number of times per hour of sleep that the SpO2 falls >/4% from the baseline e
What apnoea-hypopnea score is diagnostic of obstructive sleep apnoea?
> /15 or >5 with compatible symptoms
What is a severe sleep apnoea as classified by AHI?
> 30
What would you see in a sleep study result in someone with a central apnoea?
- Cessation of airflow
- No abdominal movement
- No thoracic movement
What underlying conditions could worsen sleep apnoea?
- Tonsils
- Hypothyroidism
- Nasal obstruction
- Obesity
- Alcohol
What does CPAP do?
- Splints the airway open
- Stops snoring
- Stops sleep fragmentation
What compliance is required for CPAP to be effective?
> 4 hours for >70% of days
What is the treatment of OSAS in someone who can not tolerate the CPAP machine?
- Mandibular advancement device
* It moves the lower jaw forwards
What is a sleep position trainer?
- Only suitable for supine OSA
- Vibrates when patient is lying on their back
- Takes weeks to change the sleeping position
What are the risks of an untreated OSAS?
- Hypertension
- Right heart strain
- Cardiovascular disease
- Increased risk of CVA
- Increased accidents at work/poor concentration
- More likely to have a road traffic accident
