Sleep Apnoea Flashcards
What is the definition of obstructive sleep apnoea?
Recurrent episodes of partial or complete upper airway obstruction during sleep with intermittent hypoxia and sleep fragmentation.
What is the definition of obstructive sleep apnoea syndrome?
Sequalae of OSA. It manifests of excessive daytime sleepiness
Explain the mechanism of obstructive sleep apnoea syndrome
- Pharyngeal narrowing occurs when there is decreased muscular tone during sleep. This can cause negative thoracic pressure causing arousal.
Arousal can lead to blood pressure surges which increases risk of MIs and strokes. It also leads to sleep disruption which reduced quality of life and increases risk of road traffic accidents
What are the symptoms of obstructive sleep apnoea?
- Snoring,
- Witnessed apnoeas,
- Disrupted sleep (chocking, dry mouth, sweating),
- Unrefreshed sleep,
- Daytime somnolence,
- Fatigue,
- Low mood,
- Poor concentration
What is involved in the assessment of obstructive sleep apnoea
- History (history from bed partner is very important),
- Clinical examination: Look at weight, BP, neck circumference (if over>40 then bad), craniofacial appearence (retrognathia/micrognathia), tonsils and nasal patency.
What is used to assess daytime sleepiness?
The Epworth Sleepiness score
What is the gold standard investigation for obstructive sleep apnoea?
Limited polysomnography (limited sleep study)
It is a 5 channel home study which measures oxygen saturations, heart rate, flow, thoracic and abdominal effort and body position.
What is method of investigating sleep apnoea which requires overnight stay in a sleep clinic?
Full Polysomnography (EEG which does sleep staging) Its advantages are the ensures correct patient, it accurately assesses sleep efficiency, it allows for sleep staging and parasomnic activity (acting out dreams or sleep talking)
What investigation of sleep apnoea should be conducted when a patient complains of headaches?
- Transcutaneous oxygen saturations and carbon dioxide assessment (used to look for CO2 retention headaches)
What is the definition of apnoea in a sleep study?
Cessation or near cessation of air flow which either results in a drop of O2 sats by 4% or lasting for 10 seconds
What is the definition of hypopnoea in a sleep study?
A reduction in airflow to a degree insufficient to meet the criteria for an apnoea
What is the definition of respiratory effort related arousal in a sleep study?
Arousal associated with a change in airflow that does not meet the criteria for apnoea or hypopnoea.
What is the Apnoea-Hypopnoea Index?
It is calculated by adding the number of apnoea’s and hypopnea’s 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 below 94%
What are the different classes of sleep apnoea?
Normal sleep - AHI <5
Mild sleep apnoea - AHI 5-15,
Moderate sleep apnoea - AHI 16-30
Severe sleep apnoea - AHI > 30
