Sleep Apnea Syndrome

Sung Chul Hwang, M.D.

Department of Pulmonary and Critical Care Medicine

Ajou University School of Medicine

Obstructive Sleep Apnea

• A disorder characterized by collapse of pharyngeal airway during sleep accompanied by arousal from sleep.

• In OSA continued ventilatory effort is present . But in Central Sleep Apnea both the ventilatory effort and air flow is absent.

Definitions ( 1 )• Apnea : complete cessation of air flow

for at least 10 seconds

• Hypopnea : reduction in air flow of more than 50 % accompanied by desaturation of at least 4% or an arousal from sleep

Definitions ( 2 )

• Apnea Index : the Average number of apneas per hour of sleep

• Apnea/hypopnea index(Resp. Disturbance Index) : Number of Apneas + hypopneas per hour of sleep

• Sleep Apnea Hypopnea Syndrome(SAHS) : patients who have sleep study based diagnosis of sleep apneas and hypopneas associated with the clinical symptoms of the disorder

• Severe SAHS : > 50 AHI

• Mild & Moderate SAHS : AHI 10 - 30

Definitions ( 3 )

Classifications

• Cerntral Apnea : No effort to breat

• Obstructive Apnea : Ventilatoey effort is presebt but no air flow because the Upper airway is closed

Epidemiology of OSA

• 9.1% of men and 4.0 % of women if AHI > 15 is used

• 3 million men and 1.5 million women with OSA ( AHI > 5 with complaint of day time sleepiness)

Pathogenesis

• Parynx is abormal in size and easy collapsibility in OSA• Changes during sleep : • Reduced tonic input to upper airway muscles• Diminished protective pharyngeal reflexes• Reduced load compensation• “set point” to increased sensitivity to hypocapnea indu

ced apneic threshold• Site of the obst. : anywhere from nose to glottis

Clinical Manifestations

During Sleep Behavioral Cardio-

respiratory

Snoring Daytime sleepiness

Nocturnal asphyxia

Nocturnal asphyxia

Traffic Accidents 2-3 tines

Tachyarryhthmia

VT, Bradycardia

Repeated

Arousal during sleep

Intellect change

Personality change

Impotence

Pul.Hypertension

RV failure

LV failure ]

Polycythemia

Increased PaCO2

Increased HCO3, Decreased Cl -

Clinical Features

Decreased pH Central Vasodilatation

Morning Headache

Decreased PaO2Arousal from sleep

Day time Somonolence

Hb desaturation Cyanosis

Polycythemia

Pulmonary Vasospasm

Cor Pulmonale

Pul. HiBP

OthersNocturnal choking episodesArousalInsomia/ sleep disruptionNocturiaG-E refluxAtypical chest painNight sweatingDecreased libidoConcentration and memory defect

Physical Examinations

• Hypertensive• Obese• Middle aged• Large thick neck “ crowded” Upper airway• Nasal Obstruction• Low hanging palate• Retrognathia• Micrognathia

Diagnosis of OSA

• History

• Physical Exam

• Routine Lab : X-rays , ABG, EKG, CBC

• Polysomnography

• Overnight Oxymetry

Polysomnography

Obstructive Sleep Apnea

Treatment (1)

• General Measures Weight control

Stop smoking

Alcohol withdrawal

Treat coexisting disease

Avoid driving motor vehicles

Treatment (2)

• Correct Anatomic Airway obstruction• Enlarged tonsils or adenoids

• Skeletal abnormalities involving craniofacial configurations

• Nasal obstructions

Treatment (3)

• Nasal CPAP• Treatment of choice for OSA

• Well tolerated in 80 % of patients

• Nasal masks, nasal Prongs, Oronasal masks

CPAP inObstructive Sleep Apnea

Treatment (4)

• Surgical Procedures• Tracheostomy• Uvulopalatopharyngoplasty (UPPP)• Maxillofscial surgery combined with UPPP• Laser Assissted Uvulopalatoplasty(LAUP)• Consider in those CPAP is not an option• Effective in Snoring but tend to recur

Treatment (5)

• Oral Appliances• Mandibular advancement prostheses

• Improve upper airway patency

• Hold the tongue foward

Mandibular Advancement Splint

Maxillofacial Advancement Surgery for OSA

Cardiac Ischemia During Apneic Episode

Obstructive Sleep Apnea

Central Sleep Apneas

Sung Chul Hwang, M.D.

Dept. of Pulmonary and Critical Care Medicine

Ajou University School of Medicine

Central Sleep Apneas

• Central apneas reflect unstable breathing control

• Decreased resp. drive : Hypoventilation during sleep --> Hypercapneic CSA

• Increased resp. drive : Hyperventilation during wake and sleep --> Hypocapneic CSA

Mechanisms

• Result of abolished ventilatory motor out-put

• Hypocapnea during NREM sleep is the major cause of reduced ventilatory motor out put

Pathogenesis• Instability often occurs at sleep onset : PaCO2 d

uring awake is less than required for rhythm generation in sleep

• Enhanced by chronic hyperventilation during wakefulness and hypocapnea below threshold

• Hypoxia, Aggravation of cardiorespiratory disease, Hyperventilation, Pulmonary congestion

• Circulatory slowing due to cardiac failure lead to ventilatory instability

Clinical Features• CSA is an alveolar hypoventilation syndro

me• Daytime hypercapnea and hypoxemia• Recurrent resp. failure, polycythemia, Pul.

hypertension, Rt. heart Failure• Poor sleep, morning headaches, daytime fat

igue, somnolence, nocturnal awakenings, etc

Diagnosis

• Clinical features

• Definitive Dx : Polysomnography

• Measurement of transcutaneous PaCO2

• Defect in Resp. control or NM function : elevated Ps CO2 that tend to increased during night esp. REM sleep

Central Sleep Apnea

Treatment• Nocturnal O2 to correct Hypoxemia• Acetazolamide -> Acidosis -> increase venti

lation• Nasal CPAP : increasePaCO2 as the added

expiratory mechanical load • Nasal CPAP is particularly effective in CS

A secondary to CHF in improving sleep quality and daytime cardiac condition

Disoders of Ventilation

Sung Chul Hwang, M.D.

Dept. of Pulmonary and Critical Care Medicine

Ajou University School of Medicine

Chemoreceptor

• Central• Medulla

Oblongata• pH, PaCO2, PaO2• fall in pH of ECF

and Carotid body• Fine regulation

• Peripheral• Aortic and Carotid

body• PaO2• dominant during

Chronic hypoxia• Coarse regulation

Alveolar Hypoventilation• Increased PACO2 & PaCO2 above normal• Impaired respiratory drive: brain stem, car

otid body trauma• Reduction in over all minute ventilation: re

sp. muscles, spinal cord, peripheral nerves • Impaired respiratory apparatus : chest wal

l, airways and lung

Neuromuscular Disorders

• Spinal cord, peripheral nerves, respiratory muscle disease

• orthopnea, paradocxical movement of abdomen and diaphragm

• Dx : Rapid deterioration of MVV, reduced PImax, PEmax, reduced transdiaphragmatic pressures and response to phrenic nerve stimulations

Pathophysiology• Increased PACO2 & PaCO2• Respiratpory Acidosis• Metabolic compensation -- increase in HCO3 --• Decrease in Cl -• Decrease in PAO2 & PaO2• Pulmonary vasoconstriction, Pulmonary hypert

ension, RV hypertrophy, CHF (Cor pulmonale)

Mechanoreceptor• Stretch receptor : smooth muscle of

trachea and main bronchus• Irritant receptor : beneath the epithelium

of larynx, trachea, bronchi• J- receptor : periphery of lung • C- receptor : pulmonary interstitial space

near pulmonary and bronchial circulation

Clinical features

• Hypoxemia, cyanosis, polycythemia• chronic hypoxemia , hypercapnea, pulmonary

HTN, CHF• ABG abnormality esp. in sleep and sleep distur

bances• Sx : morning headache, fatigue, daytime somnol

ence, mental confusion, intellectual impairment• specific features of underlying diseases

Diagnosis

• Defect in Control System : impaired response to chemical stimuli, able to hyperventilate voluntarily

• Defects in N-M System : Unable to hyperventilate, abnormal static and dynamic lung measurements

• Defects in Chest wall, Lungs, Airways : normal airway resistance and compliance, widened (A-a) DO2

Treatment

• Treat individual underlying disease• Correction of Metabolic Alkalosis• O2 supplements• Respiratory Stimulants (medroxyprogesteron

e)• Mechanical Ventilation : especially during sle

ep• Diaphragmatic pacing

Primary Alveolar Hypoventilation(Ondine’s Curse)

• Chronic hypoxemia and hypercapnea without identifiable cause

• defect in metabolic respiratory control• 20 - 50 yrs of age males• Sx and Signs of alveolar hypoventilation • treatment : general supportive care for hy

poventilation

Obesity-Hypoventilation SD (Pickwickian SD)

• Massive obesity • Reduced FRC• Underventilation of Lung base and widening of (A-

a)PO2• Chronic hypercapnia, hypoxemia, polycythemia, p

ulmonary HTN, Right heart failure• Sx : OSA, sleep induced hypoventilation• Tx : stop smoking, weight reduction, correct OSA,

medroxy progesterone

“Panda-Eye” Sign

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