Sleep disorders Flashcards
What is Cheyne-Stokes respiration?
Central apnoea/hypopnoea alternating with respiratory phase of crescendo-decrescendo pattern of flow
What are risk factors for OSA and AHI>15?
- Elevated BMI (strongest risk factor)
- Male sex
- Older age
- Neck circumference (men >43cm, women >37cm)
- Snoring
- Witnessed apnoeas
- Menopausal women
- Craniofacialabnormalities
- High Mallampati score (2 fold increase in risk of OSA with each increase in MP score)
Pathophysiology of narcolepsy
Autoimmune destruction of hypothalamic neurones that produce hypocretin which regulates arousal and sleep/wake cycle
What is the definition of AHI?
Apnoea-Hypopnoea Index:
Number of these events per hour
What are the two types of sleep?
REM and non-REM
What proportion of total sleep does REM constitute?
~20%
What is the definition of apnoea?
Cessation of airflow for >= 10s
What is the definition of hypopnoea?
Reduction in airflow by 30% for >= 10 seconds followed by:
- desaturation of 4%, or,
- EEG arousal
Sleep Foundation Survey (Australia, 2016)
8.3% Australian Adults have OSA
What is RERA?
Respiratory effort related arousal:
Events of increased respiratory effort for >=10 seconds associated with EEG arousal but not meeting criteria for hypopnoea
What is RDI?
Respiratory disturbance index:
AHI plus RERAs
Approach to narcolepsy
Sleep study to exclude other causes Urine drug screen Mean sleep latency test (MSLT) -series of naps set 2 hours apart -MSLT of <8 minutes associated with onset of REM periods is highly suggestive of narcolepsy
What constitutes non-REM sleep?
Divided into N1/N2/N3
Progressively “deeper” sleep
What is the treatment for narcolepsy?
Dexampheatmines or modafinil / armodafinil
Treat cataplexy with SSRI/SNRI
What is narcolepsy?
Intrusion of REM-sleep into wakefulness
OSA treatments
Risk factor modification CPAP Oral appliances Surgery (tonsillectomy, bariatric surgery) Maxillofacial surgery - rarely used
What is a sleep epoch?
30 seconds of sleep recording
What are the types of narcolepsy?
Type 1 - Excessive daytime sleepiness for >3months and either:
- cataplexy and positive mean sleep latency test (MSLT) or
- low CSF hypocretin
Type 2
Excessive daytime sleepiness >3 months
Cataplexy is absent
Positive MSLT with normal CSF hypocretin
Requires exclusion of other causes of sleepiness
What is the treatment for OHS?
CPAP or NIV
consider NIV up-front if primary ventilatory failure without significant OSA
How many types of sleep study are there? What do they entail?
4 types
Type 1 - polysomnography (lab study), measures over 7 metrics
Type 2 - home study, measures at least 7 metrics
Type 3 and 4 - limited studies for screening for OSA
Can you use the Epworth slepiness scale to diagnose OSA?
No, it measures sleepiness
What sleep disordered breathing types occur in heart failure?
OSA and cheyne stokes respiration
What is central sleep apnoea?
Reduction / cessation in airflow due to absent or reduced respiratory effort
What is STOP BANG?
Screening tool for OSA Snoring Tiredness Observed apnoeas Blood Pressure BMI Age Neck circumference Gender
