9/25- Obstructive Sleep Apnea Flashcards
What 2 main categories is sleep divided into? Subdivisions?
NREM: non-rapid eye movement sleep
- 4 stages (1-4)
- More sleep time is spent in stage 2
- Respiration and muscle tone ~ awake
REM: rapid-eye movement sleep
When does REM begin? Recur?
REM begins 90 min after sleep onset and reoccurs every 90 min
Characteristics of REM sleep
- Muscle tone
- Loss of skeletal muscle tone (including the diaphragm and intercostal muscles)
- Autonomic instability with fluctuations in BP and HR
What changes in ventilation occur during REM sleep?
- Decrease in tidal volume with little change in respiratory rate (decreased minute ventilation)
- Respirations are irregular
- FRC decreases due to loss of muscle tone
- These changes increase the vulnerability to develop respiratory problems and arterial desaturation
In supine sleep, what do sleep apnea patients experience in their upper airways?
Upper airway dilating muscles relax during sleep; in OSA, cannot overcome the negative inspiratory pressure in the airways
Define apnea
- Obstructive apnea
- Central apnea
- Mixed apnea
> 10s pause in respiration during sleep; several types
- Obstructive: occurs when respiratory effort is present without airflow; no air flow with continued effort
- Central: lack of airflow and respiratory effort
- Mixed: combo of obstructive and central
What does this polysomnogram show?
The tracings are:
- Airflow
- Respiratory channel (chest mvt)
- Abdominal movement
From left to right, the sections are
- Central apnea: no effort in RC/AB wtih apnea
- Obstructive apnea: RC and AB function, but still apnea
- Mixed apnea: no effort and then some effort in RC/AB but still apnea
Define hypopnea
Reduction of airflow accompanied by O2 desaturation of 4%+
What is:
- Apnea Index?
- Apnea Hypoxia Index?
- Respiratory Distress Index?
- Apnea Index = number of apneas per hour of sleep
- Apnea Hypopnea Index (AHI) = number of apneas + hypopneas per hour
- Respiratory Distress Index (RDI) = apnea + hypopneas + respiratory effort related arousal (RERA), which is a reduction in airflow (no cessation or desaturation) causing the brain to wake up at an EEG level to induce breathing
How much of the population is affected by obstructive sleep apnea?
- Epidemiology
- Estimated 2-4% (possibly > 25% if > 65 yo)
- Contributes to > 38,000 cardiovascular deaths
- Loss of productivity due to excessive daytime sleepiness
What are this risk factors for OSA?
- Obesity/fat distribution (including neck thickness)
- Age
- Male > female
- Familial/Genetic
- Snoring (probably more symptom than RF)
- Oral/facial abnormalities (short mandible or maxilla)
- Hypothyroidism/acromegaly (soft tissue infiltration)
What is required for OSA diagnosis?
- Unexplained excessive daytime sleepiness
- (AHI > 5/hr) at least 5 obstructed breathing events per hour of sleep
What are indications for the evaluation of OSA?
- Rule out apnea (for other conditions)
- Sleepiness
- Insomnia
- Snoring
- Sleepwalking
Typical phenotype of OSA pt?
- Male (6-10x)
- Middle-aged to elderly (apneas increase with age)
- Overweight (80%) (>50% with BMI > 30 kg/m2)
- Hypertensive (50-90%)
- Presents with history of snoring and daytime sleepiness
How can an individual decrease their apea?
Weight loss
Snoring is a significant symptom in OSA, but most snorers doe NOT have OSA. What is snoring associated with?
- Linked to what
- Snoring = very prevalent
Associated with:
- Decreased daytime alertness
- Higher incidence of HTN, CVA and angina.
May be part of a continuum to the development of OSA
- Likely to be older, overweight, males (same clinical profile as OSA)
Sleepiness Facts (:
- Sleepiness is a drive state like hunger or thirst.
- Sleep occurs only if there is an underlying physiologic need to sleep.
- Situations such as boredom do not cause sleep, they only permit sleep.
What is the Epworth Sleepiness Scale?
How likely you are to doze off in certain situations in contrast to feeling tired. Score > 8 hours indicates… ?
What is the DDx for excessive daytime sleepiness?
- Insufficient sleep
- Narcolepsy:
- Idiopathic hyper-somnolence (long sleep periods)
- Sleep-related periodic leg movements
- Drugs: Sedatives, Stimulants, Alcohol
- Endocrine disorders: Hypothyroidism
Describe Narcolepsy
- Prevalence compared to OSA
- Typical age group affected
- Symptoms
- 50 x less common than OSA
- Symptoms 10-30 years old (teens)
- Cataplexy, sleep paralysis, sleep attacks
How is OSA diagnosed?
Polysomnography (PSG)
What is seen here?
Polysomnagraph
Advantages/disadvantages of home sleep studies?
Advantages:
- Lower cost/tes
- Convenience
- Study patients in home setting
- This is becoming much more utilized!
Disadvantages:
- Less complete
- Inability to correct technical malfunction
- Intervention (i.e. CPAP titration) limited
What is the morbidity of OSA?
- Restless sleep
- Intellectual deterioration
- Daytime sleepiness
- Personality changes (some kids with OSA had tonsillectomy and their ADHD went away)
- Chronic hypoventilation (problems including CO2 retention)
- Pulmonary hypertension
- Nocturnal arrhythmias (when O2sat is falling)
- Right heart failure (due to repeated hypoxemias)
Other consequences of OSA?
Cardiovascular
- Hypertension
- MI risk (increases 20%)
Cerebrovascular
- CVA risk (increases 40%)
Diabetes
- Increased insulin resistance; independent of obesity
Liver-increased steatosis and fibrosis independent of obesity
Anesthetic Risk-perioperative risk Accidents!
Pathogenesis of Apnea/adverse consequences?
Apnea -> Asphyxia
- Low oxygen levels
- Loud snoring
- Sleep disturbance
- Increased heart rates
- Increased blood pressure
T/F: OSA causes increased mortality
True
- Sleep-disordered breathing was associated with all-cause and cardiovascular disease–related mortality; association most apparent in men aged 40–70 y with severe disease (AHI>30 events/h).
What is the indication for treatment with OSA?
- EDS (Epworth > 11 or problems with driving/working) AND RDI > 15
- Treatment improves symptoms, sleepiness, driving, cognition, mood, QOL and BP
- RDI 5-15 AND EDS or impaired neurocognitive function, mood disorders, insomnia, cardiovascular disease of a history of stroke
- Treatment improves symptoms
- No EDS and SDB-?
- No evidence for benefit of treatment
What is the therapy for OSA?
- General measures
- Surgical
- Others
General measures
- Avoidance of alcohol, sedatives
- Weight loss
- Avoidance of supine sleeping position
Dental appliances (mandibular repositioning splint)/Oral devices
Nasal CPAP* or BiPAP (*Treatment of choice)
Surgical options
- Uvulopalatopharyngoplasty (UPPP), LAUP
- Tonsillectomy in children
- Tracheostomy
- Bariatric surgery
Efficacy of positive airway pressure therapy (CPAP)?
- Proven in randomized placebo-controlled trials to improve breathing during sleep, sleep quality, EDS, BP, vigilance and cognition
- Proven to improve metabolic syndrome in patients with OSA
- Titration required to determine ideal pressure for patient
Describe Central Apnea again
Pause in effective respiration secondary to the absence of respiratory effort (lack of central drive to ventilatory muscles)
What are hallmarks of central apnea
- Expiratory flow
- Effort
- Etiology
- Flat line on expiratory flow (i.e., apnea), plus:
- No respiratory effort on chest wall/abdominal strain gauges Etiology, usually seen in:
- Cardiac failure (CHF): thought to be due to dilation of aorta and reduced baroreceptor feedback?
- CNS disease (post CVA, tumors, etc.)
What is the treatment for central apnea?
- Management of underlying pathophysiology (i.e. CHF)
- CPAP
- Respiratory stimulants rarely work.
- O2 relieves desaturation, but may prolong the apnea
- If severe, may require nocturnal mechanical ventilatory assistance
What are Periodic Limb Movement in Sleep (PLMS)?
- Definition
- Prevalence
- Treatment
Recurring muscle contraction of the extremities which may or may not result in sleep disruption/arousal
- Fragmented sleep leads to EDS
- Found in 13% c/o insomnia, 6% c/o sleepiness
Treatment:
- Dopaminergic agents (carbidopa/levodopa)
- Opioids/benzodiazepines
- Anticonvulsants (carbamazepine, valproate sodium)
- Clonidine
What is Restless Leg Syndrome?
- Define
- Symptoms
- Timing
- Rule out what?
- Treatment
Sensorimotor disorder with irresistable urge to move legs
- Creepy-crawling sensaion in legs
- Worse in evening or night
- Interferes with inablity to fall asleep
- Sx appear with inactivity and improve with movement
Rule out iron deficiency
Treatment with dopaminergic drugs
What is the tetrad of narcolepsy?
- Excessive daytime sleepiness
- Muscle atonia during wakefulness (cataplexy)
- Hypnagogic or hypnopompic hallucinations
- Sleep paralysis (It’s like REM sleep induced during awakening)
Describe narcolepsy
- Age affected
- Diagnosis
- Treatment
- Symptoms commonly in 2nd decade
- Diagnoses with PSG followed by multiple sleep latency test (MSLT)
Treatment is symptomatic:
- Modafinil; Methylphenidate; Dextroamphetamine for EDS
- Tricyclic antidepressants or GHB for cataplexy
What is REM Behavior Disorder?
- Symptoms
- Treatment
Normal muscle atonia seen during REM stage is lost
- Pts describe symptoms of acting out their vivid dreams
Treatment is Clonzepam
(Not sleep walking; sleep walking is considered a non-REM behavior (walking, talking, eating, not acting out dreams)
Summary: - Normal sleep is divided into NREM and REM sleep stages - Sleep apnea is cessation of airflow during sleep. - Obstructive sleep apnea is when apnea occurs despite chest and abdominal respiratory efforts and is due to airway obstruction - Central sleep apnea is when apnea occurs due to absence of respiratory efforts - OSA under recognized disorder and prevalence numbers likely underestimate the magnitude of disorder. Obesity epidemic contributing - Excessive daytime sleepiness and snoring are the two most common presenting symptoms of OSA - The apnea/hypopnea index (AHI) is the number of apneas or hypopneas per hour of sleep - For the diagnosis of sleep apnea, the AHI should be ≥ 5. - Obstructive sleep apnea(OSA) can lead to many comorbidities including HTN, stroke and death - Treatment of sleep apnea consists of sleep hygiene, weight loss and PAP (positive airway pressure) therapy
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