Transcript Chapter_30

Chapter 30
Disorders of Sleep
Objectives
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Identify the estimated prevalence of obstructive sleep
apnea (OSA) in the general population.
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Define OSA, central sleep apnea, combined sleep
apnea, and overlap syndrome.
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Explain why airway closure occurs only during sleep.
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State the possible long-term consequences of
uncontrolled OSA.
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Objectives (cont.)
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List the clinical features associated with OSA.
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Describe how OSA is diagnosed.
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Describe the treatments available for patients
with OSA.
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State how continuous positive airway
pressure (CPAP) works.
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Objectives (cont.)
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Identify the problems associated with CPAP in the
treatment of OSA.
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Describe when bilevel pressure is useful in the
treatment of OSA.
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Describe “auto-titrating” CPAP in the treatment of
OSA.
Describe the surgical alternatives for patients with
severe OSA.
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Definitions
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Sleep apnea
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Obstructive sleep apnea
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Effort but no airflow due to upper airway obstruction
Central sleep apnea
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Repeated episodes of no airflow for 10 seconds
CNS fails to signal respiratory effort
Mixed apnea: elements of obstructive and central
apnea
Hypopnea: decrease in breathing but still airflow
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Pathophysiology
Obstructive sleep apnea (OSA)
 Primary cause is small or unstable pharyngeal airway.
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OSA increases risk of systemic and pulmonary HTN.
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Contributing: obesity, tonsillar hypertrophy, small chin
During sleep, upper airway dilator muscles relax, allowing
narrowing or closure in one to many sites.
Related to increased sympathetic tone
Right ventricular failure may occur if not corrected.
Suspect OSA in obese patients with excessive daytime
sleepiness (EDS).
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Pathophysiology (cont.)
Central sleep apnea (CSA)
 Heterogeneous group of disorders
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Characterized by periodic breathing
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Waxing and waning of respiratory drive
Noted by an increase then a decrease in f and VT
Cheyne-Stokes respirations
• Often occur in CHF or stroke
• Severe type of periodic breathing
• Pattern of crescendo-decrescendo with hyperpnea alternating
with apnea
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Pathophysiology (cont.)
Overlap syndrome
 COPD patients with coexisting OSA
 Patients are typically obese smokers with moderate
to severe nocturnal oxyhemoglobin desaturations.
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Worst events occur during REM
Worse prognosis and ABGs, then OSA without
COPD
Undiagnosed OSA complicates COPD patients with
nightly arousals, dyspnea, desaturations resistant to
O2
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Clinical Features
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Tend to be men (3:1 ratio men to women), >40 years of
age with HTN
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Report snoring that has become progressively worse, tied
to sensation of choking, gasping, or snorting
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Disturbed sleep leads to fatigue, EDS, irritability,
depression, possible neuropsychological deficits
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May have right heart failure secondary to pulmonary HTN
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More common in overlap syndrome or severe obesity
Increased risk of cardiac arrhythmia associated with
moderate to severe desaturations
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Laboratory Testing
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Polysomnogram (PSG)
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Overnight study required for definitive diagnosis
Record several physiological parameters:
• EEG, EOG, chin EMG, and ECG
• Airflow at nose and mouth
• Ventilatory effort by inductive plethysmography
• Oxygen saturation by pulse oximetry
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Laboratory Testing (cont.)
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Interpretation of PSG
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Effort detected but no airflow, with or without desaturation,
defines OSA
Effort detected with minimal airflow, with or without
desaturations, defines hypopnea
No effort and no airflow, with or without desaturations,
defines CSA
Scoring of PSG
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Number of apneas and hypopneas per hour reported as an
apnea-hypopnea index (AHI)
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Laboratory Testing (cont.)
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Severity of OSA defined
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Normal:
Mild:
Moderate:
Severe:
AHI < 5
AHI 5–15
AHI 15–30
AHI > 30
Additional information reported
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Number of arousals/hour (arousal index)
Percentage of each sleep stage
Frequency of oxygen desaturation, mean SpO2, lowest SpO2
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Treatment
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Behavioral interventions and risk counseling
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Counsel on risks of uncontrolled sleep apnea
Behavioral interventions that may be useful
• Weight loss if obese
• Avoidance of alcohol, sedatives, and hypnotics
• Avoid sleep deprivation
Positional therapy (avoid supine position)
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If sleep study notes OSA occurs only supine—avoid
Tennis ball at nape of neck will discourage position
Typically only useful in mild OSA
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Treatment (cont.)
Medical interventions
• Positive pressure therapy (first-line therapy for OSA)
• CPAP of 7.5–12.5 cm H2O alleviates upper airway
obstruction in most patients
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Best titrated during sleep study
Shown to:
• Decrease EDS and improve neurocognitive testing
• Decrease incidence of pulmonary hypertension and rightsided heart failure
• Decrease ventilation-related arousals and nocturnal cardiac
events
• Improved daytime oxygenation and ventilation
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Treatment (cont.)
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CPAP therapy (cont.)
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CPAP works by pressure splinting the airway open.
CPAP titration should stop all apneic episodes and reduce
number of hypopneas.
Improved sleep occurs with obliteration of breathing related
EEG arousals and microarousals.
Patient compliance is key to CPAP success (80%).
Bilevel pressure therapy (BiPAP)
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Better tolerated by patients with high CPAP levels
Assists in ventilation as well as airway splinting
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Treatment (cont.)
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Autotitrating devices (smart CPAP)
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Adjust to varying patient needs
Use computer algorithm to adjust CPAP to changes in
airflow and/or vibration (snoring)
Average pressures may decrease
Side effects and troubleshooting strategies (PPT)
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Claustrophobia and skin irritation: change interface
Nasal congestion, rhinorrhea, nasal dryness, irritation
• Topical steroids, antihistamines, nasal saline sprays,
lotions
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Treatment (cont.)
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Side effects and troubleshooting strategies
(cont.)
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Sensation of too much pressure
• Ramp-up of pressure over a number of minutes MAY be
useful (no evidence)
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Pressure leaks
• Mouth breathers have problems with nasal masks.
• Add a chin strap to close mouth or change to full mask
(oronasal).
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Treatment (cont.)
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Oral appliances (second-line therapy)
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Devices that enlarge airway by:
• Moving mandible forward
• Keeping the tongue forward
May be useful with mild OSA if cannot tolerate CPAP
Fitted by dentists, fairly well tolerated
Medications
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Ineffective for most patients with sleep apnea
 Antidepressants may be useful for mild cases (rare)
 Oxygen helps avoid desaturations.
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Treatment (cont.)
Surgical interventions
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Uvulopalatopharyngoplasty (UPPP)
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Reconstructs portions of uvula, soft palate, and soft tissue of
pharynx
Success is less than 50%.
Not currently recommended for management of OSA
Maxillofacial surgery (more promising)
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Phase I: UPPP, genioglossal advancement, and hyoid bone
resuspension
Phase II: Only if phase I is unsuccessful, then advance
maxilla and mandible
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Treatment (cont.)
Surgical interventions (cont.)
 In worst cases (nonresponsive to all other
management techniques), a tracheostomy
may be performed that bypasses the
obstruction in OSA.
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