obstructive sleep apnea and obesity hypoventilation syndrome Flashcards
breath cessation for at least 10 sec
apnea
decrement in airflow with drop of oxygen saturation of at least 4%
hypopnea
ventilatory effort is absent for the duration of the apneic episode
central apnea
Ventilatory effort is absent in first portion followed by its reappearance during the apneic episode
mixed apnea
Ventilatory effort persists throughout the apneic episode, but no airflow occurs because of transient obstruction of the upper airway
Obstructive apnea
Obstructive and mixed sleep apneas are more common and may be associated with daytime somnolence that impacts quality of life and, in severe form, is associated with severe hypoxemia during sleep that may cause:
◦ Life-threatening issues cardiac arrhythmias
◦ Pulmonary HTN
◦ Right-sided heart failure
◦ Systemic HTN
◦ Secondary erythrocytosis
Sleep disorder characterized by repetitive complete (apneas) or partial (hypopnea) upper airway
collapse
obstructive sleep apnea (OSA)
obstructive sleep apnea can lead to
◦ recurrent arousals and cyclical hypoxemia
◦ chronic and sustained systemic and pulmonary HTN and arrhythmias
complete cessation of airflow for ≥ 10 seconds
apnea
partial airflow obstruction often resulting in arousal from sleep
hypopnea
number of apneas and/or hypopneas per hour of sleep
Measured via sleep study (in-lab polysomnography or home study)
Apnea-hypopnea index
OSA- Risk Factors
Obesity
Large neck circumference
Male sex
Older age
Snoring
Cigarette smoking
Use of alcohol or sedatives before sleeping
Craniofacial abnormalities
Endocrinopathies
◦ Acromegaly
◦ Hypothyroidism
◦ Primary aldosteronism
More common among Asian, Black, Native American, and Hispanic ethnicities
partial obstruction of the airway
snoring
complete obstruction of the airway
OSA
suspect in pts presenting with:
◦ Snoring
◦ Witnessed breathing pauses
◦ Restless or nonrefreshing sleep
◦ Awakenings (with gasping or paroxysmal nocturnal dyspnea)
◦ Insomnia
◦ Excessive daytime sleepiness or fatigue
OSA
◦ Patient-reported questionnaire which may be used to assess patient’s perception of sleepiness
The USPSTF does not recommend screening asymptomatic adults for sleep apnea
- how likely they are to doze of in different situations
epworth sleepiness scale for OSA
Modified Mallampati score 3-4 (low visibility of posterior pharynx when patient opens mouth)
Retrognathia or increased overjet (top incisor teeth ahead of bottom incisors)
Lateral peritonsillar narrowing
Macroglossia
Tonsillar hypertrophy
Elongated or enlarged uvula
High-arched or narrow hard palate
Nasal abnormalities (polyps, deviated septum, turbinate hypertrophy)
Measure neck circumference (“bull neck”)
OSA physical exam
complete visualization of the soft palate
mallampati score: Class 1
complete visualization of the uvula
mallampati score: Class 2
visualization of only the base of the uvula
mallampati score: Class 3
soft palate is not visible at all
mallampati score: Class 4
abnormally large tongue
macroglossia
OSA diagnostics
in lab polysomnography (PSG) (sleep study)- “gold standard” diagnostic test
Confirmed by number of obstructive events (apnea, hypopnea, or respiratory event-related arousal) on PSG is ≥ 5 events/hour (with symptoms) OR >15 events/hour (without symptoms)
OSA severity (respiratory disturbance index- (RDI)
◦ Mild
◦ RDI ≥ 5 events/hour and < 15 events/hour
◦ Moderate
◦ RDI ≥ 15 events/hour and < 30 events/hour
◦ Severe
◦ RDI ≥ 30 events/hour
In those with OSA and HTN
screen for primary aldosteronism
OSA- Treatment
CPAP (steady steam of air from mask that opens airway)
- weight reduction in obese individuals
- avoid alcohol and hypnotics
- oral appliances
- modafinil- improves daytime sleepiness
surgical procedures if
◦ Obvious anatomical obstructions
◦ Fail or do not tolerate initial therapy with CPAP or MAD
OSA follow up
◦ Polysomnography should be performed to assess improvement in disease severity
PICKWICKIAN SYNDROME OR HYPERCAPNIC SLEEP APNEA
obesity hypoventilation syndrome
Chronic condition characterized by:
◦ Obesity
◦ Daytime hypoventilation
◦ Sleep-disordered breathing
May result in respiratory, metabolic, and cardiovascular impairments
Caused by a failure of normal compensatory mechanisms to counterbalance consequences of
excess weight on the respiratory system
obesity hypoventilation syndrome (OHS)
OHS risk factors
Risk Factors
Obesity (esp. BMI >40)
Preexisting OSA
◦ Most patients with obesity-hypoventilation syndrome also suffer from OSA (90% of patients)
◦ Must be treated aggressively if comorbid disorder
OHS Diagnostic Criteria
BMI ≥ 30
Hypoventilation during awake hours- characterized by:
◦ Hypercapnia
◦ Serum bicarbonate level is supportive
Sleep disordered breathing diagnosed by polysomnography
Exclusion of other causes of alveolar hypoventilatio
OHS- History
Patients may have symptoms consistent with nocturnal hypoventilation:
◦ Waking headaches
◦ Peripheral edema
◦ Hypoxemia (arterial oxygen saturation <94% on room air)
◦ Unexplained polycythemia
Stable patients may have symptoms consistent with OSA (reported in up to 90%)
General
◦ BMI- ≥ 30
◦ Breathing pattern- may be shallow and rapid
Neck
◦ Circumference
◦ Large neck circumference (mean neck circumference 42.2 cm with OHS vs. 40 cm with OSA)
◦ Jugular venous distention?
◦ Right heart failure?
Extremities
◦ Peripheral edema
◦ Right heart failure?
OHS PE
OHS- Work-Up
Arterial blood gas
Overnight in-lab polysomnography
Daytime finger pulse oximetry
PFTs
ECG and TTE
TSH
Hemoglobin
OHS- Treatment
Goals: normalize sleep breathing, reduce weight, improve respiratory drive
CPAP is first line
Avoidance of:
◦ Sedative hypnotics
◦ Alcohol
◦ Opioids
Adjunct therapy:
◦ Dietary consult
◦ Physical activity
◦ Oxygen
Non-invasive ventilation for respiratory failure
Bariatric surgery
Patients with OHS have higher risk of complications in the perioperative period including:
◦ Respiratory failure
◦ Intubation
◦ HF
