SM 185a - Sleep Flashcards
What is sleep good for?
(What is happening in our body when we sleep?)
- Memory consolidation
- Energy conservation
- Brain restoration
- Protective behavioral adaptation
- Immune function
How does the following change during an episode of upper airway obstruction?
Stroke volume
Decreases
Due to pumonary vasoconstriction and septal bowing into the LV
How does the following change during an episode of upper airway obstruction?
Venous return
Increases
Due to negative intra-throacic pressure
The _______ principle and the ________ effect contribute to the physics of OSA
The Bernoulli** principle and the **Venturi effect contribute to the physics of OSA
How does the following change during an episode of upper airway obstruction?
LV afterload
Increases
Due to negative intra-thoracic pressure
What are the symptoms of OSA?
- Unrefreshing sleep
- Daytime sleepiness/fatigue
- AM headache
- Memory and learning impairments
- Hyperactivity (especially in children)
- Insomnia
- Vivid dreams
- Snoring
How does the following change during an episode of upper airway obstruction?
Transmural pressure
Increases
-> Increased LV afterload and venous return
What is the prevalence of OSA?
2-24%, depending on the population
Hormonal systems’ contributions to OSA physiology have been noted in which medical conditions?
(Select all that apply)
- Post-menopausal women
- Polycystic ovary disease
- Hyperthyroid disease
- Addison’s disease (low cortisol)
- Diabetes
- Hyperparathyroidsism
a. Post-menopausal women
b. Polycystic ovary disease
e. Diabetes
Which arrhythmias are more common in patients with OSA?
Atrial fibrillation
Tachy-Brady syndrome
*Note: People with OSA have worse outcomes with cardioversion after atrial fibrillation
How does OSA impact risk of CV events?
OSA = increased risk of CV events
Also, worse outcomes for people with known CAD and OSA
Which of the following patients would be most likely to benefit from CPAP therapy?
- A 42 year-old female with BMI 28 and AHI 7, without significant symptoms
- A 75 yeal-old male with heart failure with a recent, large embolic stroke
- A 56 year-old male with BMI 35 and AHI 66
- A 62 year-old female with amyotrophic lateral sclerosis and significant dyspnea when supine
c. A 56 year-old male with BMI 35 and AHI 66
What are the anatomical risk factors for OSA?
Oropharyngeal crowding that impedes airflow
May be caused by…
- Excessive tissue
- Obesity, tonsillar hypertrophy
- Micrognathia (small chin)
- Macroglossia
- Impaired oropharyngeal muscle tone
List some of the cardiopulmonary effects of OSA
- Upper airway obstruction -> negative intrathoracic pressure
- Increased transmural pressure
- Increased LV afterload
- Increased venous return
- Hypoxia due to obsruction
- Pulmonary vasoconstriction + Septal bowing into the LV
- Decreased LV filling
- Stroke voume
- Pulmonary vasoconstriction + Septal bowing into the LV
How can you tell the difference between obstructive and central apnea?
Why is it important to do so?
No airflow in both central and obstrutive sleep apnea
-
Central: No diaphragmatic excursions
- The patient is not trying to breath
- There is central dysregulation of the breathing pattern
- Treatment: Requires breathing machine that can provide a backup rate
-
Obstructive: Diaphragmatic excursions
- The patient is trying to breathe, but air is not flowing
The Bernoulli principle contributed to models of sleep apnea becasue…
- Air temperature affects airway caliber
- The upper airway is a non-rigid “floppy” tube
- Sleep stage (REM slee) impacts upper airway muscle tone
- Age-related changes affect upper airway patency
b. The upper airway is a non-rigid “floppy” tube
There is a _______ higher risk of atrial fibrillation in patients with OSA
There is a 4-fold higher risk of atrial fibrillation in patients with OSA
Why are men at a higher risk for OSA than women?
Testosterone can induce sleep-disordered breathing
Men have more testosterone than women
How do you know if an apea is obstructive?
Active effort but impaired flow
You will see periods of zero airflow with diaphragmatic excursions: The patient is trying to breathe, but air is not flowing
How many sleep cycles do we normally have per night?
4-5
How does the ratio of N3 (deep) sleep to REM sleep change with successive sleep cycles during the night?
The first sleep cycle has very little REM sleep and a lot of N3 (deep) sleep
As the night continues, each successive cycle contains less N3 sleep and more REM sleep
Which populations are most at risk for OSA?
- Overweight and obese
- Men and women with large neck sizes
- Middle-aged and older men
- Post-menopausal women
How does the following change during hypoxia caused by an episode of upper airway obstruction?
LV filling
Decreases
Due to pulmonary vasoconstriction + septal bowing into the LV
What breathing pattern is this?
What does it indicate?
Cheyne-Stokes breathing
It indicates dysregulation of the body’s normal response to changed PCO2 levels
How is the Ventrui Effect relevant to the upper airway?
The narrowest part of the airway creates disproportionate intraluminal pressure in the upper airway, resulting in flow limitation, and facilitating airway collapse
How is OSA diagnosed?
Polysomnography (gold standard)
What is the Bernoulli Principle?
How does it apply to OSA?
As the speed of a moving fluid increases, the pressure within the fluid decreases
In the narrow regions of the airway, air must flow faster to maintian adequate flow
As it flows faster, it has less pressure and therefore less potential energy
This is called the Ventrui Effect
OSA can have long-term effects on which systems?
Cardiovascular
Cognitive
Quality of life
What is the impact of OSA on catecholamine levels?
Increased catecholamine levels
(These wake you up when breathing stops - basically, they are released when your brain is panicking)
This is not good for your heart
What is the difference between obstructive and central sleep apnea?
- Obstructive = airway/tube issue
- Central = brain/controller issue
Pulmonary HTN is present in _____% of OSA patients
Pulmonary HTN is present in 20% of OSA patients
Most likely with cocomitant lung disease
What is the impact of OSA on sympathetic tone
Sympathetic tone increases
This causes vasoconstiction, and can impair LV filling and stroke volume
What is the most important complaint when screening with either the Berlin or STOP questionnaires?
a. Drowsy Driving
b. Diabetes
c. Memory Loss
d. Loud Snoring
e. Insomnia
d. Loud Snoring
What are the mechanisms of the cardiac effects of OSA?
Each obstructive event adds fuel to the fire
- Hypoxemia
- Repeated arousals
- Sustained increased catecholamine levels
- Increased sympathetic tone
- Increased endothelin secretion
- Alterations in eicosanoids
How do troponin-1 levels change in people with severe OSA?
What does this indicate?
Troponin-1 levels are elevated in people with severe OSA
This implies that there is chronic, low-level myocardial injury
