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
What is N3, non-REM sleep also referred as?
Slow-wave sleep
What are the characteristics of REM sleep?
Atonia (detected by EMG)
Tonic/Phasic eye movements (detected by EOG)
PICKWICK trial
N 215, randomised to CPAP or NIV
3 years follow up
No significant difference in outcomes
What is the pathophysiology of OHS?
Reduced lung volumes, respiratory muscle weakness, reduced chest wall compliance, leptin resistance, serum bicarb
Results in blunted respiratory drive
What is the theshold for increased neck circumference?>
Men>43cm
Women >37cm
What is the all cause mortality of OHS at 2 years?
24%
What is the treatment for sleep disordered breathing in heart failure?
Optimise medical therapy
OSA - CPAP may improve EF, BP, exercise capacity and QOL
Cheyne stokes - CPAP, oxygen or BiPAP
**Adaptive servo ventilation (ASV) increases mortality in HF patients with cheynestokes
What is cataplexy?
Sudden, transient loss of skeletal muscle tone, usually triggered by laughter in narcolepsy type 1
What is sleep hypoventilation?
Uses transcutaneous CO2 monitoring
Rise of CO2 >=10mmHg to above 55mmHg above baseline
What are the benefits of CPAP?
Improved sleepiness, QOL, depression, cognitive function, reduced hypertension, reduces risk of MVA.
What percentage of people continue to use CPAP beyond 5 years?
65%
What is obesity hypoventilation syndrome?
OHS
Awake hypercapnia
BMI >30
Sleep disordered breathing without other lung disease
What is the increased risk of motor vehicle accidents in those with moderate/severe OSA?
4x increased risk
Does OSA increase all cause mortality?
Yes, 3x with severe OSA
What effect does OSA have on AF?
Higher symptom burden, antiarrythmic use, hospitalisation due to AF
No increase in AF related mortality
