Pulmonary Sleep Disorders Flashcards
sleep apnea
*repeated cessation of breath > 10 seconds during sleep → disrupted sleep → daytime somnolence
*diagnosis confirmed by sleep study
*nocturnal hypoxia → systemic and pulmonary hypertension, arrhythmias (atrial fibrillation/flutter), sudden death
*hypoxia → increased EPO release → increased erythropoiesesis
*several types: obstructive sleep apnea (OSA) central sleep apnea, hypoventilation syndromes
obstructive sleep apnea (OSA) - overview
*a sleep order characterized by:
-MECHANICAL OBSTRUCTION of the upper airway
-repetitive cessation in respiration when sleeping
-repetitive disruptions in sleep (frequent awakenings) known as MICROAROUSALS
-daytime fatigue & sleepiness
obstructive sleep apnea (OSA) - risk factors
*age
*obesity
*male gender
*craniofacial and upper airway abnormalities
*disorders of the CNS
*medications (respiratory depression)
obstructive sleep apnea (OSA) - signs and symptoms
*hypertension
*obesity
*large neck circumference
*crowded oropharynx
*micrognathia
*snoring
*morning headaches
*difficulty staying sleep
*daytime sleeping
obstructive sleep apnea (OSA) - diagnosis
*CBC demonstrating polycythemia in severe cases
*in-home apnea testing
*in-lab polysomnogram (GOLD STANDARD)
*diagnostic criteria:
-15 obstructive apnea episodes per hour
OR
-5 obstructive apnea episodes per hour with snoring or pauses in breathing and associated daytime symptoms
obstructive sleep apnea (OSA) - treatments
*weight loss
*exercise
*abstain from alcohol & respiratory depressants
*oral surgery/dental devices
*continuous positive airway pressure (CPAP)
*surgery
obstructive sleep apnea (OSA) - complications
*arrhythmias (ventricular tachycardia, bradycardia, stroke)
*daytime fatigue
*pulmonary hypertension
*right ventricular failure (cor pulmonale)
*type 2 diabetes
*CAD
*stroke
central sleep apnea - overview
*increased number of apneas due to LACK OF RESPIRATORY DRIVE (vs. functional obstruction seen in OSA)
*can be sporadic or cyclical
*may be associated with Cheyne-Stokes respirations
*associated with: insomnia, age, comorbid conditions, nocturnal chest pain, daytime sleepiness
central sleep apnea - etiologies
*stroke
*heart failure
*CNS injury/toxicity
*opioids
Cheyne-Stokes breathing
*seen in patients with: heart failure; strokes
*characterized by HYPERVENTILATION (decreasing CO2) followed by APNEA & HYPOVENTILATION (increasing CO2)
*“crescendo-decrescendo” pattern
*note - can be seen in central sleep apnea
central sleep apnea - treatment
*correct or treat underlying disorder
*CPAP + BiPAP
hypoventilation syndromes - examples
- obesity hypoventilation syndrome
- hypoventilation due to COPD
- neuromuscular
- chest wall abnormalities (kyphoscoliosis, post thoracoplasty, etc)
- hypoventilation due to underlying parenchymal or vascular disease
hypoventilation syndromes - general pathophysiology
*2 mechanisms can lead to hypoventilation:
1) DECREASED ALVEOLAR MINUTE VENTILATION
2) INCREASED Vd/Vt (increased dead space)
obesity hypoventilation syndrome - overview
*aka Pickwickian syndrome
*characterized by:
-obesity (BMI > 30)
-awake and nocturnal hypoventilation and hypoxemia
-sleepiness
-polycythemia
-Cor Pulmonale
*highly associated with OSA
obesity hypoventilation syndrome - diagnosis
*ABG: hypoventilation / hypercapnia (PCO2 > 45 mmHg)
*obesity (BMI > 30)
*lack of other etiology of hypoventilation (such as COPD)
*polysomnogram to diagnose confounding OSA
obesity hypoventilation syndrome - pathophysiology
*obesity → hypoventilation → increased PaCO2 during waking hours → decreased PaO2 and increased PaCO2 during sleep
*adipose tissue leads to a “mass load” on the chest wall, causing increased work of breathing and LOWER LUNG COMPLIANCE
obesity hypoventilation syndrome - treatment
*CPAP in selected patients
*BiPAP
*advanced non-invasive positive airway pressure therapy
*weight loss
hypoventilation due to COPD - diagnosis
*history of COPD (chronic bronchitis or emphysema) [note - this occurs in SEVERE cases, not mild]
*ABG: hypercapnia & hypoxemia
*polysomnogram to diagnose concomitant OSA
hypoventilation due to COPD - pathophysiology
*progressive FEV1 decline, air trapping → less capacity to maintain alveolar minute ventilation
*associated with progressive muscle weakness
*INCREASED Vd/Vt ratio (dead space ratio) due to:
-reduced alveolar minute ventilation → rapid shallow breathing
-air trapping
-emphysema
*OSA syndrome often present
hypoventilation due to COPD - treatment
*treat underlying COPD (helps decrease air trapping, maximize FEV1, prevent exacerbations)
*BiPAP to improve ventilation
hypoventilation-neuromuscular disorders - examples
*Guillain-Barre syndrome
*ALS
*acute polymyositis
*spinal cord traum
*etc
*overall: SYMPTOMS OF NM DISORDER + hypoventilation syndrome
hypoventilation-neuromuscular disorders - pathophysiology
*common underlying mechanisms include:
-muscle weakness → “restrictive” physiology
-reduced alveolar minute ventilation
-INCREASED Vd/Vt ratio (dead space)
*exacerbating factors:
-recumbent position → diaphragm disadvantage
-REM sleep (skeletal muscle atonia)
hypoventilation-neuromuscular disorders - diagnosis
*underlying NM disorder present
*ABG for morning hypercapnia
*PFTs:
-LOWER FVC in SUPINE position vs. UPRIGHT
-restrictive pattern
-low maximal voluntary ventilation
*low maximum inspiratory pressure
*low maximum expiratory pressure
*sniff test
hypoventilation-neuromuscular disorders - treatment
*treat underlying NM disorder if possible
*non-invasive PAP (BiPAP)
*surgical tracheostomy with nocturnal or continuous mechanical ventilation
