Obstructive Sleep Apnoea Flashcards
what is the definition of OSA
cessation of airflow for >10sec despite evidence of continued respiratory effort, due to repetitive collapse of upper airway.
OR
cyclical interruption of ventilation, each cycle lasting 15-90s and resulting in hyperaemia, hypercapnia, and resp acidosis terminating in an arousal from sleep followed by the resumption of normal ventilation, a return to sleep and so on.
Who are more likely to have OSA
Men are twice as likely as womrn
How common is OSA
~20 %
what is the pathophysiology of OSA
reduced upper airway size due ti excess surrounding soft tissue or a highly compliant airway.
what risk factors are there for OSA
obesity cranio-facial and upper airway soft tissue abnormalities genetic smoker (2x more likely) nasal congestion
What co-morbidities is OSA associated with?
Heart failure
stroke
COPD
interstitial pulmonary fibrosis
What are the classic features of OSA
- obstructive apneas, hypopnoeas, or respiratory effort related arousals
- Daytime symptoms - sleepiness, fatigue, poor concentration
- signs of disturbed sleep - snoring, restlessness or resuscitative snorts.
What objective scales can be used to measure OSA and its symptoms?
fatigue severity scale
epworth sleepiness scale
When would you perform a polysomnography/alt sleep study
complaints of snoring with daytime tiredness, or >2 clinical features, or mission-critical worker repeat a normal test if high clinical suspicion
what other symptoms may present with OSA
insomnia, sore/dry mouth, moodiness/irratbility, morning headaches, depression, dcr libido, poor concentration
what is polysomnography
full/split night, attended in lab
who would be a suitable candidate for home sleep studies?
Pt with high positive predictive probability and no com-morbities
What grades are there for OSA
mild/mod/severe
what is the definition of mild OSA
apnoea hypopnoea index: 5-15 events /hr,
asymptomatic
some day time somnolence, not affecting ADLS
30% respond to treatment
mx behaviourally
generally no assoc co-morbidities
what is the definition of moderate OSA
apnoea hypopnoea index 15-30 events /hr pt aware of daytime sleepiness - tries to avoid falling asleep HTN possible nil other assoc co-mrbidities responds to CPAP generally
what is the definition of severe OSA
apnoea hypopnoea index >30 events /hr and/or dcr sats to <90% for more than 20% of total sleep time
daytime sleepiness that interferes with daytime activities
multiple co-morbidities
Prompt Rx- CPAP, Surgery
tracheostomy in very severe cases with life threatening apnoeas
what is your differential for daytime sleepiness causes
periodic movements of sleep rotating shift workers narcolepsy upper airway resistance syndrome central sleep apnoeas respiratory disease primary snoring GORD
what are the driving regulations for someone who has OSA
For those with dx from a sleep study and excessive daytime sleepiness and thought to be at risk due to the level of sleepiness — NO licence
if they are compliant with treatment and have had a satisfactory response they can have a CONDITIONAL
License, subject to periodic review and if Dr thinks suitable.
what behavioural therapies for OSA are there?
weight loss >10% smoking cessation positional avoidance of alcohol and sleep deprivation medication review nasal obstruction
What pressure devices are there and what is the benefit
CPAP
BPAP
APAP
they reduce the number of apnoeas and improve QOL
what are the treatment options for OSA
behavioural
pressure
oral appliances
surgery
How do oral appliances in OSA work?
They push the mandible forward, or hold the tongue in a more anterior position
How affective are oral appliances
They decrease the frequency of respiratory evens
improve daytime sleepiness/QOL and neurocognitive function
Are there any drugs that can help OSA
no, none have been proven to be effective
when should you refer an OSA pt
socially disruptive snoring despite optimal behavioural management
snoring assoc with CV co-morbidities 0 HTN, IHD, stroke, TIA, Diabetes
Snoring assoc with MVA, excessive sleepiness, inattention at work impaired cognition.
what age does OSA plateau
55-65yrs
