Sleep And OSA Flashcards
(32 cards)
What are the 2 processes of the sleep model
Circadian rhythm
Homeostatic drive to sleep
How does the circadian rhythm regulate sleep
Light exposure
24 h cycle
Generated from the suprachiasmatic nucleus (SCN)
What is a zeitburger
Environmental agent providing stimulus for biological clock
Light is most important
What is homeostatic drive to sleep
Longer you are awake with neural activation there is a build up of adenosine which increases need to sleep
What is melatonin
Hormone that causes sleepiness
What effects melatonin release?
Light or dark
Light at correct time strengthens circadian rhythm
Effect of blue light on melatonin
May switch it off
Stages of sleep
Stage 1 (5%)
Stage 2 (50%)
Stage 3 (slow wave/deep sleep)(20%)
REM sleep (25%)
How are sleep stages measured
Brain activity on EEG during sleep
Each stage of sleep exhibits different waveforms
What is a hypnogram
Graphical representation of sleep stages
What conditions do you see in a sleep service
OSA
Upper airway resistance syndrome(UARS)
Obesity hypoventilation syndrome
(OHS)
Central sleep apnea (CSA)
Neurological disorders
What is OSA?
Periodic narrowing and obstruction of the upper airways during sleep despite ongoing effort to breath
What happens during OSA episode
Reduction in O2 to brain increase CO2
Brain responds by making pt rouse
Airways reopen
Adrenaline response and surge in BP and HR
Risk factors for OSA
Fhx
Male
> 40
Crowded/narrow pharynx
Obesity
Symptoms of OSA
ESS >10
Snore
Apnoeas
Restless/unrefreshing sleep
Cause of OSA
Multi factorial
Mainly due to muscle relaxation, so there is a loss of contraction of pharyngeal dilators leading to narrowing/collapse
Can also be more likely due to someone’s anatomy
Most common contributory factor for OSA
Obesity
Sleep investigations for OSA
Pulse oxim
Resp polygraphy
Full polysomnography
Poligraphy results for OSA
Apnoea - hypopnoea index >5 per hour
O2 desat >5 per hour (3% drop)
Snore
HRV
Maybe slight reduction in resp effort
Clinical impact of OSA
Hypertension
Atherosclerosis
Diastolic dysfunction
HF
Stroke
Arrhythmia
Diabetes
What is upper airway resistance syndrome (UARS)
Similar symptoms to OSA but normal test results ie <5 episodes per hour
Leads to OSA
Treatment for OSA
Lifestyle changes
Mandibular advancement device
Mainly CPAP
Sometimes ENT surgery if appropriate
What is obesity hypoventilation syndrome (OHS)?
Nocturnal alveolar hypoventilation due to obesity
Defined as combo of obesity and daytime hypercapnia (PCO2 >45mmHg or >6kPa
