Obstructive Sleep Apnea

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Obstructive Sleep Apnea
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What is OSA?

• OSA is a syndrome characterized by frequent
  episodes of upper airway obstruction during
  sleep, associated with recurrent arousals, oxygen
  desaturation, and daytime symptoms
• OSA is not a disease in itself, but rather a
  final common pathway of many disorders

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Prevalence of OSA
Self-reported hypersomnolence plus AHI gt5
Wisconsin Sleep Cohort Study 1993
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Prevalence of OSA
Self-reported hypersomnolence plus AHI gt5
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Wisconsin Sleep Cohort Study 1993
Indian data - 7.5
Udwadia et al, AJRCCM 2004
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Pathophysiology of OSA

• Interplay between three important factors
• Anatomic Structural narrowing of airway
• Neurologic Inadequate upper airway dilator
  muscle function
• Mechanical Altered upper airway collapsibility

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Anatomical narrowing

• Excessive adipose tissue around pharynx
• Increase in soft tissue volume (e.g. enlarged
  tonsils, macroglossia, acromegaly)
• Craniofacial anomalies (e.g. micrognathia,
  retrognathia, TM joint degeneration)
• Other minor abnormalities (e.g. differences in
  airway shape and orientation, inferiorly
  displaced hyoid bone, enlarged soft palate)

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Veasey, CCNA 2003
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Neuromuscular dysfunction

• Inadequacy of airway dilator muscles
• Tonic activity
• Phasic inspiratory activity
• Influenced by several factors (neural drive,
  chemical drive, lung volume, input from upper
  airway receptors)

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Airway dilators at work
Tensor Veli Palatini (V) Levator Veli Palatini (V)
Pharyngeal constrictors (X)
Genioglossus (XII) Geniohyoid (XII) Anterior
Digastric (VII)
Geniohyoid (XII) Styloparyngeus (IX)
Sternohyoid (XII) Omohyoid (XII) Sternothyroid
(XII) Mylohyoid (V)
CCNA 2003
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Pharyngeal luminal area
100
0
Airway suction
Dilator muscle tone
Proprioceptors
Inspiratory drive
Upper airway drive
Central breathing control
Peripheral chemoreceptors
Central chemoreceptors
Kryger 2000
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Increased airway compliance

• Retropalatal and retroglossal region
• Tendency of oropharyngeal closure at less
  negative airway pressures
• Disorders of connective tissue
• High negative intra-airway pressures during
  inspiratory air flow

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Sleep stage
Awake
I
II
III
IV
REM
2
0
4
6
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Sleep time (hours)
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The initial history

• Interview both patient and bed partner
• Majority of patients present with
• excessive daytime sleepiness
• neuropsychiatric symptoms
• cardiorespiratory features
• Diagnosis is often missed even though patients
  have had symptoms for years

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Excessive Daytime Sleepiness

• Sleep at night is fragmented
• Tendency to fall asleep during day
• In inappropriate settings
• At inappropriate times
• Without realizing
• Severity correlates with intensity of nocturnal
  apnea
• Epworth Sleepiness Scale (ESS)

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Epworth Sleepiness Scale

• How much do you feel like sleeping or do you
  sleep in the following states?
• Please answer without taking into consideration
  the feeling of tiredness (fatigue) that you might
  experience. We are concerned or we are referring
  to the daily way of life, during the recent
  period. Please answer the following and think
  about possible ways of influencing you, even if
  you have not experienced these states recently.
• You have to use the following rating scale for
  each of the following situations
• 0 I would never feel like sleeping
• 1 There is a small chance that I might feel
  like sleeping
• 2 Its quite probable that I might feel like
  sleeping
• 3 Its definite that I might feel like sleeping

Situation Probability (0-3)
I sit down and I do some reading ____
I am watching television ____
I am sitting in a public place, without doing anything specific (e.g. in a theater or meeting with other people) ____
I am in a car for a non-stop hour ____
I lie to bed to take some rest during the evening, provided that Ive got the chance ____
I am sitting and participating in a conversation with someone ____
I sit down in peace and quiet, after lunch, with no alcohol consumption ____
I am in the car, and I have to stop for a few minutes due to the traffic ____
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• Prevalence of habitual snoring is much higher
  than that of OSA
• Most individuals who snore do not have OSA
• Although common in patients with OSA, snoring is
  not essential for its diagnosis
• Character of snoring

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Common symptoms
Nocturnal Daytime
Snoring Sleepiness
Witnessed apnea Fatigue
Choking Morning headaches
Dyspnea Poor concentration
Restlessness Decreased libido
Nocturia Decreased attention
Diaphoresis Depression
Reflux Decreased dexterity
Drooling Personality changes
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Clinical examination

• Obesity (BMI gt28 kg/m2 )
• Neck circumference gt40 cm
• Enlarged nasal turbinates
• Deviated nasal septum
• Narrow mandible / maxilla
• Abnormal dental structure
• High and narrow hard palate
• Elongated and low-lying uvula
• Prominent tonsillar pillars
• Enlarged tonsils and adenoids
• Macroglossia

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Risk factors

• Obesity
• Advancing age
• Male gender
• Positive family history
• Race
• Alcohol ingestion
• Sedative use

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Primary events Secondary events Clinical consequences

Vibration of soft palate Snoring
Pulmonary arterial vasoconstriction Pulmonary hypertension Right heart failure
Systemic arterial vasoconstriction Systemic hypertension
Vagal bradycardia Cardiac ischemia and irritiability Cardiac arrhythmias Sudden unexplained cardiac death
Cerebral vascular dilatation Morning headache
Hypothalamic-pituitary-testicular dysfunction Reduced libido Impotence
Stimulation of erythropoeisis Polycythemia
Cerebral impairment and/or damage Excessive daytime sleepiness Intellectual deterioration Behavioural disorders
Sleep fragmentation Loss of deep sleep Excessive daytime sleepiness Intellectual deterioration Behavioural disorders
Excessive motor activity Nocturnal epilepsy
Sleep onset

Upper airway narrowing

Obstructive apnea

ipO2,hpCO2,ipH

Arousal from sleep

Airflow resumption

Return to sleep
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Diagnosis of OSA

• A. Excessive daytime sleepiness not better
  explained by other factors
• B. Two or more of the following, not better
  explained by other factors
• Choking or gasping during sleep
• Recurrent awakenings from sleep
• Unrefreshing sleep
• Daytime fatigue
• Impaired concentration
• C. Overnight monitoring shows five or more
  obstructed breathing events per hour during
  sleep (obstructive apnea, hypopnea or
  respiratory effort related arousals)
• Individuals must fulfill criteria (A or B) plus C
  for diagnosis

AASM 1999
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Sleep studies
Overnight polysomnography is the gold standard
for diagnosis of OSA

• Count number of respiratory events and divide by
  hours of sleep to generate AHI

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Abdominal
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Definitions

• Apnea is cessation of oronasal airflow, lasting
  10s
• Hypopnea is airflow reduction of gt50, lasting
  10 sec and associated with either oxygen
  desaturation or arousal
• Arousal is an abrupt shift to faster EEG
  frequency (including theta, alpha and/or greater
  frequencies, but no spindles), lasting 3 sec

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Obstructive apnea Complete cessation of airflow
despite efforts to breathe
Desaturation
Snore
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Central apnea Complete cessation of respiratory
effort and airflow
Central apnea
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Mixed apnea Complete cessation of airflow with
gradual increase in respiratory effort after an
initial absence
Desaturation
Mixed apnea
No effort
Effort
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Hypopnea Reduction in airflow compared to
baseline, associated with desaturation
Desaturation
Progressively increasing respiratory effort
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Obstructive apnea with recovery correlated
alpha-beta intrusion
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Controversies in PSG

• Standard vs. portable equipment
• Technician-attended studies
• Definitions of respiratory events (desaturation,
  arousal, etc.)
• Categorization of severity
• Whole-night vs. split-night studies

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Other evaluations

• Hematocrit, ABG, PFT, ECG
• Tests to localise obstruction evaluate upper
  airway geometry
• Radiologic
• Endoscopic
• Tests in specific clinical situations e.g.
• thyroid function, growth hormone assay

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Severity of OSA
Unintended sleep episodes RDI
Mild During activities requiring little attention (e.g. watching TV) 5-15
Moderate During activities requiring some attention (e.g. business meeting) 15-30
Severe During activities requiring active attention (e.g. driving a car) gt30
AASM 1999
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Indications for treatment

• Clinical picture is most important
• In general, treatment is indicated for
• AHI gt20
• AHI 5-20 plus daytime sleepiness and/or
  additional risk factors (hypertension, cigarette
  smoking, hypercholesterolemia, etc.)
• ? All patients

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General measures

• Weight reduction
• Avoid alcohol, sedatives, smoking
• Maintenance of good sleep hygiene
• Modification of body position at night
• Advice regarding driving vehicles
• Management of complications related to OSA

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Treatment of specific conditions

• Upper airway obstruction
• Nasal obstruction
• Enlarged tonsils or adenoids
• Face skeletal abnormality
• Systemic disorders
• Hypothyroidism Acromegaly
• Sarcoidosis Lymphoma

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Treatment when no specific cause can be
ascertained

• Nasal CPAP therapy of choice
• Other measures
• Pharmacological agents
• Mechanical devices
• Surgical procedures

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Nasal CPAP therapy for OSA

• Currently the treatment of choice
• Important considerations
• Comfortable and tight-fitting mask
• Use all night and every night
• Use during daytime naps also
• Majority require 6 - 12 cm H2O
• Level of CPAP should be determined objectively
  while patient is sleeping

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CPAP Titration
Respiratory events
Hours of sleep
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Nasal CPAP systems

• Fixed level
• Self-titrating
• Other extras
• Ramp feature
• Humidification
• BiPAP systems

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Untreated OSA
OSA treated with CPAP
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Benefits of CPAP therapy

• Improvement in neuropsychiatric function
• Lessening of daytime sleepiness
• Amelioration of
• Nocturnal desaturation
• Ventilatory-related arousals
• Nocturnal dysrhythmias
• Pulmonary hypertension
• Systemic hypertension

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Pharmacological therapy

• Protriptyline
• Oxygen
• Other agents with doubtful role
• Stimulants amphetamines, Modafinil
• Serotonin agonists Buspirone
• Agents with no therapeutic indications
• (progesterone, acetazolamide, naloxone,
  theophylline, almitrine, bromocriptine)

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Oral appliances
Mandibular repositioning device
Tongue advancing device
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Surgical treatment

• Tracheostomy
• Palatal surgery
• Uvulopalatopharyngoplasty
• Laser assisted procedure
• Maxillofacial surgery
• Genioglossal advancement
• Maxillomandibular advancement

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Role of non-CPAP therapy

• Less effective, less accepted, and less tolerated
• May be considered for
• individuals with clearly reversible causes of OSA
  (e.g. deformities)
• individuals who have failed or who refuse CPAP
  treatment
• treatment of mild OSA (?)

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SUMMARY

• OSA is one presentation in a spectrum of
  sleep-related breathing disorders
• Anatomic, neurologic and mechanical factors all
  involved in pathogenesis
• Polysomnography is the gold standard for
  establishing diagnosis
• Nasal CPAP therapy is treatment of choice in
  patients without any specific underlying cause

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