SLEEP DISORDERED breathing Flashcards
•Flow through the upper airway during sleep can be predicted using a Starling resistor model, where flow through a tube is predicted by pressures and resistances upstream and downstream to the site of collapse. During an obstructive event, what is the relationship between the pressures at the site of airway collapse (Pcrit), upstream (Pus) to the site of collapse, and downstream (Pds) to the site of collapse?
A.Pus> Pcrit> Pds.
B.Pus> Pds> Pcrit.
C.Pcrit> Pus> Pds.
D.Pcrit> Pds > Pus.
answer = c
outside pressure causing collapse of the airway
Primary muscles of sleep
1) muscles influencing hyoid position (geniohyoid/sternohyoid)
2) tongue muscles (genioglossus)
3) palate muscles (tensor palatini, levator palatini)
Effect of obesity on airway
1) airway narrowed due to incr fatty tissue around neck
2) causes collapse of pharyngeal space
3) compensate by incr force of genioglossus muscle
Physics of upper airway collapse
Snoring
1) what proportion of people occassionally?
2) habitual in men vs women
universal
44% men, 28% women
cheyne-stokes respiration
found in which patients?
what happens?
arounds occur when?
heart failure, storke
greater hypercaneic respiratory drive –> overshooting of PaCO2 below apneic threshold
1) CO2 = primary drive of breathe
2) CO2 in blood decr and delayed incr in resp neurons
(aortic and carotid bodies and medulla)
3) exaggerated response and overshoot target
blow down CO2 too low so long pause
when CO2 rise then breathe again
–> arousals occur at peak of ventilation
•A 62 year old man presents to clinic with the chief complaint of daytime sleepiness for the past 6 months. He is unable to stay awoke while watching television in the evening and his wife is concerned about his driving. His wife also states that he struggles to breath during sleep. He has a history of hypertension and diabetes. His Body Mass Index is 38 and neck circumference is 56cm. Which of the following diagnostic tests would provide the definitive diagnosis for this patient?
A.Nocturnal oximetry
B.Serum TSH level
C.Multiple Sleep Latency Test
D.MRI of the head and neck
E.Polysomnography
answer = e
polysomnography
underlying co morbidity and postiive sleepiness –> high pre test probability
Sleep apnea assoc with?
1) obesity
2) CV disease
3) MVC
Consider what questions for sleep in patient?
- Is the patient overweight or obese?
- Is the patient retrognathic?
Does the patient complain of daytime sleepiness?
- Does the patient snore?
- Does the patient have hypertension?
Assess which patients for OSA symptoms?
- Morbidly obese- BMI >35
- CHF
- Atrial fibrillation
- Treatment refractory hypertension
- Type 2 diabetes
- Nocturnal dysrhythmias
- CVA
- Pulmonary hypertension
- High-risk driving populations
- Preoperative for bariatric surgery
Demographics of OSA
1) gender
2) age
3) race
4) PMH
5) FHx
6) SHx
7) meds
1) male more
2) prevalence incr until 60’s and 70’s
3) minorities
4) chronic rhinitis, acromegaly, neuromuscular disorder, amyloidosis, down
5) 1st degree relative with OSA
6) smoking, etoh abuse
7) sedative-hypnotics, opioids
Features of sleep apnea
- Morning headaches
- Nonrestorative or unrefreshing sleep or naps
- “Restless” sleep with frequent movements
- Awakenings with a sensation of gasping or choking
- Excessive body movements during sleep
- Snoring
- Witnessed apneas, gasping, or choking
- Daytime sleepiness or fatigue
- Decline in performance at work or school
- Attention deficit (in children)
- Hyperactivity (in children)
- Impaired cognition (memory and concentration)
- Impotence or diminished libido Insomnia
- Nocturia or enuresis
Physical exam
Mallampati
more crowding in posterior pharynx had incr risk during intubation
class 3 and class 4 are also incr risk of OSA
Polysomnography
full night (diagnostic or therapeutic)
split night ( (diagnostic or therapeutic))
portable study ( (diagnostic or therapeutic))
when do you use portable study?
full night = diagnostic purpose only
split night = diagnostic (1/2 night) + therapeutic (1/2 night with CPAP) only
portable = diagnostic
high pre-test probability and no cardiopulm comorbidities
•Which of the following surgical procedures is most likely to be definitively successful for the treatment of severe obstructive sleep apnea syndrome (OSAS) in an adult patient?
A.Uvulopalatopharyngoplasty
B.Tonsillectomy and adenoidectomy
C.Maxillomandibular advancement
D.Tracheostomy
●
answer = D
Treatment of OSA
1) avoid sedatives, stop smoking (because incr inflamm of oropharynx and narrow arirway), treat underlying
2) weight reduction
3) position therapy, O2, pharmaco, positive airway
4) upper airway surgery
5) nerve stim
Describe CPAP
Describe bi-level positive airway pressure
describe autotitrating positive airway pressure
describe nocturrnal noninvasive positive pressure ventilation
constant pressure throughout resp cycle
2 pressure levels - high during inspiration, lower during expiration (helps ventilation; if not only obstruction but also ventilation)
looks at breath to breath and augments pressure to ventilate well
ventilator for central or complex or mixed sleep apnea
oral appliances for OSA
tongue retainer
when to use?
holds tongue forward
preferred for edentulous patients or those with no dentition
oral appliances for OSA
mandibular repositioner
don’t use if (2)
advance mandible forward
1) don’t use if inadeq or broken teeth
2) don’t use if significant TMJ dysfunction
surgical options for OSA
tracheostomy
used for?
tracheostomy
tracheal opening distal to pharynx to bypass upper airway obstruction
curative for severe sleepiness, cardiac arrhythmia, severe hypoxemia, hypoventilation, cor pulmonale
may still hypoventilate so still need additional ventilation
surgical options for OSA
maxillomandibular advancement
goal
maxillomandibular advancement
advance maxilla and mandible
enlarge retrolingual and retropalatal airway
surgical options
UPPP
more or less effective than CPAP
good long-term?
UvuloPalatoPharyngoPlasty
excision of uvula, posterior soft palate, tonsils
less effective than CPAP
recurrence of snoring or OSA after initial benefit
Surgical options for OSA
tonsillectomy and adenoidectomy
remove tonsils/adenoids
effective in children with OSA
nerve stimulation for OSA
for mild OSA not want CPAP
implanted into skin and insert into genioglossus and intercostal muscle so when do respiratory effort, sends signal to genioglossus to contract and move it out of oropharynx
Most common cause of OSA is ____
Related to this is:
periodic collapse of pharyngeal soft tissue during sleep
1) obesity
2) anatomically small pharyngeal airway
3) loss of tone of pharyngeal or genioglossus
4) unstable respiratory control system
5) low arousal threshold
6) changes in lung volume/loss of coordination of airway
Patients with OSA have a reduced ____ due to XS soft tissue (fat) or a higly compliant airway
upper airway
Patients with OSA have a reduced upper airway due to (2)
1) XS soft tissue (fat)
2) highly complaint airway
What can result in partial or complete upper airway collapse in OSA
1) reduced airway size
2) diminished neural input to upper airway muscles
What determines the tendency of upper airway to collapse?
Critical closing pressure (Pcrit)
Apneas occur when ___ is less than the threshold for inspiratory muscle activation to maintain upper airway patency during sleep
If an overshoot in ventilation decr CO2, what happens to respiratory drive
Thus, the next apnea results from ___
respiratory drive
fall below the threhsold for inspiration to occur
overcompensation for prior apnea
Apneas occur when respiratory drive is less than ___
threshold for inspiratory muscle activation and maintaining airway patency during sleep
Prevalence of apnea
what % of adults at risk for apnea
if the prevalence is defined as an apnea hypopnea index >5 events per hour (asymptomatic)
if the prevalence is defined as an apnea hypopnea index >5 events per hour + at least one symptom known to respond to treatment (daytime sleepiness)
26%
20%
2-9%
therefore, common to be asymptomatic
how does OSA prevalence change with age and gender and race
incr from 18-45 then plateaus at 55-65
more common in african americans < 35 compared to whites and common in Asians
males more than women due to higher apnea hypopnea during adulthood (little difference beyond 60’s)
if a patient says that they are feeling sleepy or falling asleep in boring or passive situations, this could imply ___
daytime sleepiness
if a patient snores 9common in OSA), what else could they also likely have?
excessive daytime sleepiness
what are common symptoms in OSA?
1) XS daytime sleepiness
2) restless sleep
3) silence, then loud snoring
4) poor concentration
5) waking up gasping, choking
each apnea event results in arterial ___ and ___
hypoxemia and hypercarbia d
what do arterial hypoxemia and hypercapnia in OSA cause?
1) sympathetic hyperexcitation
2) incr peripheral vascular resistance
3) TRANSIENT SYSTEMIC HYPERTENSION
4) precapillary pulmonary vasoconstriction –> pulmonary hypertension
5) vagal tone via carotid body hypoxic stim –> bradycardia
why do patients with OSA have pulm hypertension
due to precapillary pulmonary vasoconstriction
what causes the bradycardia that occurs in OSA during an apneic episode
carotid body hypoxic stim (breath holding)
what happens when the patient wakes up from an apneic episode?
1) aroused
2) pharyngeal patency
3) hyperventilate
4) blood gas back to normal
what are treatment plan for apnea
1) CPAP –> good for sleepiness, cog function
1) lifestyle mod = weight loss, exercise
2) sleep position (cervicomandibular support, pillow)
3) mandibular repositioning and tongue retaining
4) CNS stim
5) surgery
what are surgical procedures for OSA
1) oral/oropharyngeal/nasopharyngeal procedures
2) hypopharyngeal procedures
3) airway
4) laryngeal procedures
Paradigm of checking for OSA
1) clinical probability of positive test for sleep apnea
2) low neck circumference
–> daytime symptoms = conservatve if none to mild
polysomnography = moderate to severe
3) large neck –> polysomnography
if polysomnography not available use portable monitor
what happens to airway during sleep? how does this affect neck muscle motor activity?
when in deep sleep, motor activity of neck decr significantly
how does airway resistance change with sleep
1) airway narrowed
2) incr resistance
3) body compensates by incr pull of muscles to open airway
4) chronically incr baseline EMG activity due to incr force
how does sitting and standing affect airway size
what happens with OSA
airway size decr with supine due to tongue falling back to neck
in sleep apnea, start with smaller airway and more compromise with supine
Describe Zone 3
best situation because pressure in upper airway > lower airway > Pcrit
so airway always open
Describe Zone 2
snoring
prssure upper airway > P crit > pressure lower airway
upper still greater than lower so air goes downstream but due to narrowing from P crit, create snoring
Describe zone 1
P crit > P upstream > P downstream
obstructive sleep apnea
collapse of the straw in all situations causing incr turbulence and obstructed airflwo
