Post on 15-Apr-2017
transcript
Evaluation of OSA
Dr Manohar, Resident ENTINHS ASVINI
• Introduction
• Aetiopathogenesis
• Clinical Presentation
• Classification
• Definitions:
• Apnea
• Hypoapnea
• Physiology of sleep:
• Non-REM Sleep: four stages
• Stage I (2-5%)
• Stage II (45-55%)
• Stage III (3-8%)
• Stage IV (10-15%)
• REM Sleep
• 20-25%
• Dreaming activity
• Muscular activity
Respiratory physiology during normal sleep
• Regulated by:
• 1. Chemical factors: O2, CO2, acidosis
• 2. Mechanical signals from lung, airway, and chest
receptors
• REM sleep: decreased sensory and motor function
->impairment of ventilatory responses->
hypoventilation
Respiratory physiology cont...
Hypoxic and hypercapnic ventilatory response during sleep
• During sleep voluntary control of respiration
is lost
• Ventilatory responses to both low O2 and high Co2
levels blunted -> marked hypoxemia seen during
REM sleep
Respiratory physiology cont...
Effects of sleep on respiration
Arousal responses to respiratory alterations during sleep
• Isocapnic hypoxia
• Hypercapnia
• Increased airway resistance: Inspiratory resistance
and occlusion strong precipitants of sleep arousals
Classification of Obstructive Sleep-RelatedBreathing Disorders
• 1. Snoring
• 2. Upper Airway Resistance Syndrome
• 3. Obstructive Sleep Apnea Syndrome
• Snoring:
• sound generated by the vibration of the pharyngeal
soft tissues.
• 40% of men and 20% of women
Classification cont...
Upper Airway Resistance Syndrome
• UARS is characterized by respiratory effort–related
arousals (RERAs).
• A RERA is defined as a sequence of breaths over at
least 10 seconds with increasing respiratory effort
that terminates with an arousal.
Classification cont...
• Obstructive Sleep Apnea Syndrome
• Five or more respiratory events (apneas,
hypopneas,or RERAs) in association with excessive
daytime somnolence, waking with gasping, choking,
or breath-holding, or witnessed reports of apneas,
loud snoring, or both.
Classification cont...
• EPIDEMIOLOGY and RISK FACTORS
• Obesity and Metabolic syndrome
• Neck size
• Adults and children with Down Syndrome
• Children with large tonsils and adenoids
• Endocrine disorders such as Acromegaly and
Hypothyroidism
• Smokers
Aetiopathogenesis
• Nose
• Nasal blockage might:
• Reduce nasal afferent reflexes that help to maintain
muscular tone of the upper airway
• Augment the tendency for mouth opening
• Reduce humidification, increase mucus viscosity, and
increase surface tension forces
• Increase upstream airway resistance, predisposing to
downstream airway collapse.
Aetiopathogenesis contd...
• Upper airway dilating muscles
• Activated by negative airway pressure
stimulating nasal and laryngeal receptors
• Recurrent hypoxia impaired dilating muscle activity
Aetiopathogenesis contd...
• Oval upper airway (fat deposition)-> impair upper
airway dilator muscle function
• Upper airway oedema-> chronic vascular over
perfusion, mechanical trauma (snoring)
Aetiopathogenesis contd...
• Pharyngeal soft tissues:
• Supine position
• MRI volumetric studies->tongue
size as a major predictor
• Sagittally oriented airways that were speculated to
result in unfavorable muscular mechanics for reopening
the airway
Aetiopathogenesis contd...
• Oral to palatal airspace is smaller, and the posterior
airspace behind both the tongue and palate is
narrower.
• Cross-sectional shape of the airway- elliptical
• Biomechanically weaker structure that is more easily
collapsed at less negative pressures.
Aetiopathogenesis contd...
• Body/jaw position/gravity
• Structural considerations
• Balance of forces
Aetiopathogenesis contd...
Consequences of OSAH syndrome
Aetiopathogenesis contd...
• Fujita classified ( Anatomical basis)
• Type I- collapse in the retropalatal region
• Type II- collapse in both retropalatal and retrolingual
regions
• Type III- collapse in the retrolingual region only
Starling resistor
Clinical Presentation:
• Snoring
• Fatigue
• Witnessed
breath-holds
• Gasping and choking
• ESS
• Fragmented sleep
• Reduced alertness
• Mood changes
• Nocturia
Clinical Presentation contd...
• BMI
• Neck circumference
• Complete head and neck examination
• Muller’s manoeuvre
Clinical Presentation contd...
Diagnosis
• Detailed history:
• Obtained in three settings
• First- routine health maintenance evaluation
• Second- evaluation of symptoms of OSA
• Third- comprehensive evaluation of patients of high
risk for OSA
• Overnight oximetry:
• Oxygen desaturation index
subject with ODI of 55, 4 percent oxygen dips per hour. This trace shows the whole night's data. Minimum oxygen saturation is approximately 45 percent
• Home multichannel testing:
• Advantages
• Disadvantages
Polysomnography
• Equipment
• Four types of sleep studies
• Level I:
• Standard PSG with a minimum of seven parameters
measured, including EEG, EOG, EMG, and EKG, as
well as monitors for airflow, respiratory effort, and
oxygen saturation.
• Level II:
• Comprehensive portable PSG studies are essentially
the same, except that a heart rate monitor can
replace the ECG
• Level III
• Modified portable sleep apnea testing is a
cardiorespiratory study in which a minimum of 4
parameters must be measured, including
ventilation , heart rate or EKG, and oxygen saturation
• Level IV:
• Continuous (single or dual) bioparameter recordings
where devices that measure a minimum of one
parameter, usually oxygen saturation are utilized
• EEG
• ECG
• EOM
• EMG
• Pulse oximetry
• Nasal and Oral airflow
Polysomnography contd...
• Sleep position
• Blood pressure
• Oesophageal pressure
Polysomnography contd...
Polysomnography contd...
• Polysomnography can also diagnose other sleep
disorders:
• Narcolepsy
• Periodic limb movements disorder (moving your legs
often during sleep)
• REM behavior disorder
Indices of Sleep-Disordered Breathing
• Apnea index- Number of apneas per hour of
total sleep time
• Hypopnea index- Number of hypopneas per hour of
total sleep time
• Apnea-hypopnea index Number of apneas and
hypopneas per hour of total sleep time
• Respiratory effort–related arousals (RERAs) index-
Number of RERAs per hour of total sleep time
• Respiratory disturbance index (RDI)-Number of
apneas, hypopneas, and RERAs per hour of total
sleep time
Indices of Sleep cont....
• Central apnea index- Number of central apneas per
hour of total sleep time
Indices of Sleep cont....
• Types
• Mild OSA: AHI of 5-15
• Involuntary sleepiness during activities that require little
attention, such as watching TV or reading
• Moderate OSA: AHI of 15-30
• Involuntary sleepiness during activities that require some
attention, such as meetings or presentations
Classification cont...
• Severe OSA: AHI of more than 30
• Involuntary sleepiness during activities that require
more active attention, such as talking or driving
Classification cont...
• Pulse transit time: interval between the R wave on an
electrocardiogram (ECG) and the arrival of the pulse
at the finger.
• Increased in increased respiratory effort and
decreased in the presence of tachycardia associated
with arousal.
Sleep nasendoscopy
• Rigid laryngobronchoscopy:
• Pathology distal to the glottis that may be
exacerbating the upper airway symptoms
Consequences of Untreated ObstructiveSleep Apnea
• He and colleagues- apnea index >20 increased
mortality
• Motor vehicle accidents by 2.5-fold
• Threefold increase in fatal and nonfatal
cardiovascular events
• Metabolic syndrome
• GERD
• Attention
• Working memory
Consequences cont....
References
• Scott-Brown’s 7th edition
• Cummings 5th edition
• OCNA
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