Obstructive Sleep Apnoea Flashcards
1
Q
What is OSA?
A
- Upper airway obstruction during sleep
- Upper airway narrowing, provoked by sleep causing sufficient sleep fragmentation = daytime symptoms usually excessive sleepiness
2
Q
Typical OSA patient
A
- Male
- Upper body obesity (collar size >17 inches)
- Relatively underesized mandible or set back mandible
3
Q
Pathophysiology of OSA
A
- Upper airway patency depends on dilator muscles activity - all muscles relax during sleep
- Some narrowing of upper airway is normal
Excessive narrowing can be due: - already small phargyneal size which then narrows a normal amount during sleep but causes critical narrowing
OR - excessive narrowing occuring with relaxation during sleep
4
Q
Cause of small pharyngeal size
A
- fatty infiltration of pharyngeal tissues and external pressure from increased neck fat and/or muscle bulk
- Large tonsils
- Craniofacial abnormalities
- Extra submucosal tissue eg myxoedema
5
Q
Causes of excessive narrowing of airway during sleep
A
- Obesity may enhance residual muscle dilator action
- Neuromuscular disease with pharyngeal involvement = loss of dilator muscle tone eg stroke, MND, myotonic dystrophy
- Muscle relaxants - sedatives. alcohol
- Increasing age
6
Q
Clinical effects of OSA
A
- Repetetive airway collapse with arousal needing to reactivate pharyngeal dilators –> hypoxia or hypercapnia
- Hyperfragmented sleep from arousals = unrefreshing sleep
- Excessive daytime sleepiness
- Every arousal = rise in BP of over 50mmHg, also daytime rise in BP, damage CVS unclear?
- Nocturnal sweating, reduced libido, oesophageal reflux - less common
7
Q
How is hypoxia and hypercapnia corrected?
A
- During the inter-apnoeic hyperventilatory period
8
Q
Who often witnessess OSA?
A
Partner - witnesses snoring and arousals
9
Q
What scale is used to measure sleepiness from OSA?
A
- Epworth sleepiness scale
10
Q
What is classed as excessive daytime sleepiness?
A
Epworth score of >9
11
Q
Epworth sleepiness scale point system
A
0 - would never dose
1 - slight chance
2 - moderate chance
3 - high chance
12
Q
What scenarios are asked to be scored in Epworth sleepiness scale?
A
- Sitting and reading
- Watching TV
- Sitting in public place eg theatre
- Passenger seat in car for 1hr
- Lying down to rest in afternoon
- Sitting and talking
- Sitting quietly after lunch without alcohol
- In a car, whilst stopped in traffic
13
Q
How is OSA diagnosed?
A
Sleep study
14
Q
Types of sleep studies
A
- Overnight oximetry alone
- Limited sleep study - oximetry, snoring, body movement, HR, oronasal flow, chest/abdo movements, leg movements
- Full polysomnography - limited study plus EEG, EMG
15
Q
Usual choice of study for diagnosing OSA
A
Limited sleep study
