SLEEP APNEA

SLEEP APNEA

Definition

1.     Syndrome in which repetitive episodes of cessation of airflow or decreases in airflow occur during sleep in the presence of continued respiratory effort (obstructive sleep apnea). Cessation of airflow without respiratory effort is seen in central sleep apnea. A combination of these two events is seen in mixed apneas.

2.     The Apnea/Hypopnea Index (AHI) is a method of quantifying the severity of the sleep disordered breathing. It is the sum of all respiratory events occurring over a full night divided by the total sleep time recorded in hours. An AHI>5/hour is considered abnormal in most populations, and in the appropriate clinical setting, defines obstructive sleep apnea syndrome (OSAS).

3.     Recent studies have found an incidence of OSAS of approximately 4% in middle aged US males, and approximately 2% of females. Children and infants may also be afflicted. Familial clustering has been reported.

4.     Risk factors for OSAS:

o    obesity

o    advancing age

o    snoring

o    sleep deprivation

o    ethanol and sedative/hypnotic medications

o    hypothyroidism

o    general anesthetics

o    certain antihypertensive agents (methyldopa, propranolol)

o    COPD

o    ribcage and neuromuscular abnormalities

o    CNS disorders

o    nasal obstruction

o    tonsillar/adenoidal hypertrophy

o    acromegaly

o    micro and retrognathia

o    macroglossia

o    lymphoma

o    Shy-drager Syndrome

o    amyloidosis

o    congenital syndromes

Signs and Symptoms

1.     manifestations of above mentioned risk factors

2.     excessive daytime somnolence

3.     sleep maintenance problems

4.     abnormal motor activity during sleep

5.     abnormal sleep positions

6.     parasomnias

7.     signs differ in children:

o    hyperactivity

o    irritability

o    developmental delays

o    growth retardation

Pathophysiology of Obstructive Apneas

1.     Initial pharyngeal obstruction:

o    Usually occurs at level of velopharynx, may also occur in hypopharynx

o    Pharyngeal dilator muscle hypotonia, especially during REM sleep

o    Compromised anatomy of upper airway

2.     Consequences of occlusion

o    Hypoxemia

o    Hypercapnia

o    Arousal

3.     Post-apneic Ventilation

Complications of OSAS

Cardiopulmonary

• cardiac arrhythmias and conduction disturbances
• sinus arrhythmia
• second degree or complete AV Block
• prolonged sinus pauses
• paroxysmal atrial fibrillation
• ventricular tachycardia
• systemic and pulmonary hypertension
• SBP > 200mm Hg at conclusion of obstructive events
• decreased MAP during events
• increased ischemic events (associated with BP changes and gas exchange abnormalities)
• PCWP increases (may cause pulmonary edema)
• long term consequences
• pulmonary hypertension
• cor pulmonale
• systemic hypertension
• increased vascular mortality/death

Neuropsychiatric

• excessive daytime somnolence
• personality changes
• cognitive dysfunction and memory impairment
• impotence
• depression

Socioeconomic

• loss of productivity
• increased motor vehicle accidents (7-fold increase over non-apneic controls)

Diagnostic Evaluation of Patients with Suspected OSAS

1.     History

o    typical sleep-wake cycle

o    quality of sleep

o    medication ingestion

o    habits (tobacco, caffeine, alcohol)

o    stressors

o    exercise

o    sleep environment

o    associated symptoms (morning headache, dry mouth, snoring)

o    family history of sleep disorders

2.     Physical Examination

o    HEENT

o    Hypertension

o    body habitus

o    neck size

o    cardiac exam

o    mental status

o    thyroid abnormalities

o    neuropathy

3.     Sleep Questionnaire and Diary

4.     Nocturnal Polysomnography

o    ambulatory vs. laboratory

o    AHI

o    arousal index

o    desaturations

o    arrhythmias

reatment

1.     Weight Reduction

2.     Positional Treatment

3.     Correct increased nasal resistance

4.     Dental Appliances

5.     Increase Upper Airway Muscle Tone

o    avoid alcohol, sedatives and hypnotics

o    pharmacologic intervention

o    protriptyline

o    progesterone

o    theophylline

o    strychnine/nicotine

o    electrical stimulation

6.     Nasal Continuous Positive Airway Pressure

o    standard of care

o    titrated pressure

o    nasal mask vs. pillows

o    CPAP vs. BiPAP

o    "AutoPAP" or DPAP or VPAP

o    Compliance

7.     Surgical Correction of Upper Airway Anatomic Abnormalities

o    tracheostomy

o    nasal surgery