Module 4.4 - Obstructive Sleep Apnea

Question 1

What are the characteristics of characteristics of breathing and sleep in a patient with obstructive sleep apnea (OSA)?

Answer 1

• Tidal Volume and respiratory rate decline with sleep with further decrease in muscle tone in the deeper stages of sleep.
  
  • Peak airway resistance tends to be highest from 2-6 am and lowest from 2-6 pm.
• Cough and shortness of breath may be aggravated during the normal sleeping period at night
• Normal pauses in respiration are infrequent, lasting 5-10 seconds. These pauses are central in origin and not associated with physical obstruction of the oropharynx or hypopharynx.
• Respiratory effort related arousals (RERAs) represent changes in airflow that lead to an arousal but do not meet criteria for an apnea or hypopnea
• Apnea-hypopnea index (AHI) is the number of apneas and hypopneas per hour of sleep.
  
  • Apneas = complete cessation of airflow,
  • Hyponea=diminished airflow associated with a 3-4% desaturation in oxygenation.
• Respiratory disturbance index (RDI) is the number of apneas, hypopneas and RERAs per hour of sleep

Question 2

What causes obstructive sleep apnea (OSA)?

Answer 2

It is the most common sleep related breathing disorder. It is a chronic problem that often requires lifelong treatment. It is an obstruction of the upper airway caused by loss of normal pharyngeal muscle tone during sleep. The obstruction causes arousal from sleep.

Question 3

What is central sleep apnea?

Answer 3

It is the disturbance of central control of respiration during sleep.

Question 4

What are some medical conditions that increase the risk of developing obstructive sleep apnea?

Answer 4

• Obesity (most common)
• CHF
• ESRD
• chronic lung disease
• CVA
• TIA
• acromegaly

Question 5

What are the clinical manifestations of obstructive of sleep apnea?

Answer 5

• Classic manifestation is excessive daytime sleepiness.
  
  • DO NOT DRIVE UNLESS DIAGNOSIS IS MADE AND TREATMENT STARTED
• Snoring is commonly heard but in severe cases, snoring may be quieter.
• Hypoxemia may be noted during apneic and/or hypopneic episodes during sleep.
• Patients also complain of personality changes, intellectual deterioration, morning headaches, nocturnal angina, loss of libido and chronic fatigue

Question 6

What are the physical exam findings seen in patients with obstructive sleep apnea?

Answer 6

• Mental status reflects alertness.
• Obesity with fatty infiltration of the soft palate and pharyngeal wall can be found as well as a decrease in the posterior pharyngeal space; tonsillar enlargement, if present, aggravates the obstruction.
• Right sided heart failure with peripheral edema may be seen

Question 7

What is Polysomnography (PSG) and how is it used in obstructive sleep apnea?

Answer 7

• It is an overnight sleep test that measures airflow, muscle tone, and brain activity. It is the gold standard test for the diagnosis of OSAHS
• The test involves determination of sleep stages using electroencephalography electromyography and electro oculography and assessment of respiratory airflow and effort. Other measurements include oxyhemoglobin saturation, EKG and body position. Limb movements are observed as well as other abnormal behaviors that may occur during sleep.

Question 8

What are some diagnostic tests used to diagnose obstructive sleep apnea?

Answer 8

• Respiratory disturbance index (RDI) > 5 is diagnostic of OSA
• The finding of more than 10 obstructive apneas/hypopneas per hour is abnormal and justifies treatment.
• > 30 apnea hypopnea index (AHI) is considered severe OSA and carries a higher mortality risk.
• Oxygen desaturation below 88% during sleep may require supplemental oxygen if treatment for OSA shows no improvement
• Most sleep studies are done as “split studies” where the first few hours are diagnostic and if indicated, the last hours for CPAP initiation and titration.
• Sleep studies are done in the outpatient setting and can be costly. Unattended portable monitoring is an alternative with results reviewed by a sleep specialist for interpretation and recommendations.

Question 9

What are the goals of treatment for patients with obstructive sleep apnea?

Answer 9

The goals of therapy are to reduce or eliminate apneas, hypopneas and oxyhemoglobin desaturation during sleep to improve sleep quality and daytime functioning. The severity of the disease, co morbid medical conditions, patient preference and expected compliance should be considered.

Question 10

What should patients with obstructive sleep apnea avoid?

Answer 10

• Avoid alcohol, sedatives, hypnotics and opioids until effective therapy is started.
• Avoid driving and operating heavy machinery until effective treatment is provided and a significant reduction in daytime sleepiness is noted

Question 11

How is CPAP or BIPAP used with obstructive sleep apnea?

Answer 11

• Institution of nasal continuous positive airway pressure (nCPAP) or nasal bi-levelpositive airway pressure (nBIPAP) is used to stent open the pharynx.
• The delivery system should fit snugly and provide humidification to avoid dryness of the nares.
• Pressure needed to treat OSA is usually between 5-15 cm H2O which initially may be empirically chosen, but is determined by the PSG, followed by titration as needed to fully alleviate episodes of obstruction.

Question 12

What medications are used for obstructive sleep apnea?

Answer 12

Medications- while there are no pharmacological agents that warrant the replacement of CPAP, Modafinil may improve daytime sleepiness in patients with persistent drowsiness despite CPAP.

Question 13

What are some gerontological considerations to consider with obstructive sleep apnea?

Answer 13

• The prevalence of OSA increases with age. Untreated OSA may increase the risk of metabolic syndrome or early mortality.
• Cognitive changes may be present in elderly patients with OSA; experts are unsure if these effects are due to hypoxia, hypersomnolence or both. These changes may include impairments in attention and concentration, difficulty with executive functioning and memory.
• Treatment with nCPAP or nBIPAP may improve cognitive functioning. Hypertension may improve and require less pharmacologic therapy. Blood pressures should be monitored closely and medications titrated accordingly. The elderly cannot tolerate lower blood pressures and may experience episodes of dizziness, syncope and falls.