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