Obstructive Sleep Apnea Flashcards
What percentage of patients with OSA are undiagnosed?
80-95%
What are the major risk factors for OSA?
Male Middle Age Obesity (BMI >30) Alcohol consumption Drug-induced sleep
What are the two major factors that cause sleep apnea?
Mechanical obstruction of upper airways
Loss of respiratory drive
BOTH
What does a sleep apnea cycle look like?
Oxygen desaturation
sympathetic arousal
Awakening, leading to fragmented sleep
What type of sleep is missing when a patient has untreated sleep apnea?
REM sleep
What contributes to the loss of tongue tone which leads to an occluded airway?
Genioglossus muscle becomes relaxed
What two components contribute to the classification of obstructive sleep apnea?
Cessation of air flow but maintain respiratory effort
Abnormal relaxation of the genioglossus and pharyngeal muscles which cause the tongue to fall backwards obstructing the airway
What two components contribute to the classification of central sleep apnea?
Cessation of BOTH air flow and respiratory effort
There is a problem in the ventilatory center of the medulla
What two components contribute to the classification of Pickwickian syndrome?
Severe chronich OSA leads to cor pulmonale
Related to morbid obesity
What symptoms are associated with Pickwickian syndrome?
Hypersomnolence Severe hypoxia/hypercarbia Pulmonary HTN RV enlargement Hypervolemia
Why do patients with obstructive sleep apnea complain of morning headaches?
Nocturnal CO2 retention and cerebral vasodilation
How is the severity of sleep apnea determined?
Number of apneas per hour of sleep
How many apneic episodes per hour would be considered mild sleep apnea?
5-15
How many apneic episodes per hour would be considered moderate sleep apnea?
15-30
How many apneic episodes per hour would be considered severe sleep apnea?
Greater than 30
How long does the patient have to stop breathing before it is considered apnea?
Minimum of 10 seconds cessation of breathing
What is hypopnea?
Defines by greater than 50% decrease in airflow or oxygen desaturation of greater than 4% for 10seconds or greater
What causes arousal of the patient after experiencing apnea?
Either due to the muscle work or the extreme pressure gradient and or hypoxemia
How are the respiratory muscles affected by OSA?
Diaphragm and axillary respiratory muscles become completely desynchronized
What occurs during the arousal phase of OSA?
Muscle tension is restored and free air exchange is resumed
About how many times can this cycle occur in a patient with severe OSA in one night?
300-400 times
What is the gold standard for diagnosing sleep apnea?
Polysomnography
How does CPAP help in OSA?
Attenuates hemodynamic responses induced by apnea including BP surges and increased SNS activity
How is the level of positive pressure required determined for each patient?
Sleep study
When would supplemental O2 be required for OSA?
Severe arterial oxygen desaturation
What is the name of the procedure done for OSA that removes the tonsils, part of the soft palate and the uvula?
Uvulopalatopharyngoplasty UPPP (UP3)
What is the end goal of the UP3?
To enlarge the airway
What is another type of surgery to treat OSA using heat to causing scaring of the tissue?
Diathermy Palatoplasty
What is the end goal of a diathermy palatoplasty?
Cause scaring that will contract the tissue and prevent the airway from falling
What is a major complaint with both surgeries for OSA?
Pain
About how many patients with OSA have HTN?
About 40%
How does OSA affect awake patient that are normally normotensive?
Increased sympathetic tone
BP variability
Decreased HR
Why do a lot of obese patient have an elevated aldosterone level?
Indicated RAAS activated from SNS activated by OSA
How does OSA affect the body’s immune response?
Increases level of pro inflammatory cytokines
Activated coagulation factors
Increased cholesterol levels
What percentage of stoke patients have OSA?
70%
What percentage of patients with Afib have OSA?
50%
What is the thought behind OSA causing Afib?
Dramatic shifts in cardiac transmural pressures and chamber dimensions caused by forceful ventilatory efforts against an obstructed airway
How does OSA affect pregnancy?
May be associated with:
Low birth weight
HTN and possible pre eclampsia
How does pregnancy predispose a female to OSA?
Pregnancy induced changes in the upper airway
What gender predominately has OSA?
1/3 Males and half as many females
What percentage of people are actually aware they have sleep apnea?
20%
What comorbidities have a strong correlation with OSA?
GERD
AF
HTN
What screening tool is best to use based on sensitivity and specificity on patients that may have OSA?
STOP BANG
What does the pneumonic STOP BANG stand for?
Snoring Tired during day Observed stop breathing Pressure (BP) BMI greater than 35 Age greater than 50 Neck circumference Gender male
What is considered a high risk patient after the STOP BANG tool has been used?
Yes to three or more
What is considered a low risk patient after the STOP BANG tool has been used?
Less than three
What are good tools to utilize in order to estimate peri-operative risks in patients with OSA?
History
Sleep study
Type of surgery the patient is undergoing
Questionnaire
Why should we avoid preoperative sedatives in patients with OSA?
Very sensitive to CNS depressants:
Suffer from sleepiness
Elevated SNS tone
Why might a patient with OSA be polycythemic?
May result from chronic hypoxia
What disease process can develop if OSA left untreated causes frequent periods of apnea and hypercarbia?
Cor Pulmonale
What considerations should the anesthetist take prior to intubating a patient with OSA?
The patients are often difficult to mask ventilate and trachea can be more difficult to intubate
Why are opioids use limited in patients with OSA?
Opioids take away the arousal characteristic in the cycle
How should patients with OSA be extubated?
Awake, communicating and breathing spontaneously with adequate TV and SpO2
What factors might be considered prior to extubating a patient with OSA?
Ease of mask ventilation East of tracheal intubation Nasal packing (can't use nasal airway)
What is one way that an anesthetist can extubate a patient with OSA with an insurance policy?
Leave the airway exchanger in until the patient is fully awake and doing well in the PACU
What position should the OSA patient be placed in while extubating?
Semi-upright, lateral or prone preferable to supine
Why shouldnt we extubate an OSA patient that isn’t fully reversed?
Weak diaphragm = weak small airway muscles = obstruction
Why should we minimized post operative supplemental O2?
It may be used as their drive to breath if chronically hypoxic
How much longer should OSA patient be monitored compared to patients without OSA?
3hrs longer
