Chapter 291 - Sleep Apnea Flashcards
causes daytime sleepiness, impairs daily function, and is a major contributor to cardiovascular disease in adults and to behavioral problems in children
OSAHS
Which medical condition can predispose to central sleep apnea
Heart failure
Condition the results to frequent awakening and daytime fatigue and patients are at increased risk for HF an AF
CSA
Formula for AHI
no. of episodes of A/H divided by number of hours of sleep
What are the three things that happen in every episode of apnea or hypopnea?
- reduction in breathing for at least 10 s
- ≥3% drop in O2 sat
- brain cortical arousal
OSAHS severity is based on which parameters?
- frequency of breathing disturbances (AHI)
- amount of oxyhemoglobin desaturation with respiratory events
- the duration of apneas and hypopneas
- the degree of sleep fragmentation
- level of daytime sleepiness or functional impairment
Diagnosis of OSAHS
(1) Sx + AHI 5 or more
(2) AHD >15 episodes/h
In patients with collapsible airway, Transient episodes of pharyngeal collapse result in
apnea
transient episodes of pharyngeal near collapse is manifested as
hypopnea
Episodes of collapse or near collapse are terminated how?
activation of ventilatory reflexes causing arousal
Most common site of airway collapse?
soft palate
others: tongue base, lateral pharyngeal walls, epiglottis
When is OSAHS most severe?
REM sleep
supine position
Factors that narrow the pharyngeal lumen
- enlargement of soft tissue structures
- Craniofacial factors
- Lung volume
- High degree of nasal resistance
Major risk factors of OSAHS
Obesity
Male sex
Additional risk factors of OSAHS
- mandibular retrognathia and micrognathia
- positive family history of OSAHS
- genetic syndromes that reduce upper airway patency (e.g., Down syndrome, Treacher-Collins syndrome)
- adenotonsillar hypertrophy (especially in children)
- menopause (in women)
- endocrine syndromes (e.g., acromegaly, hypothyroidism).
How many percent of cases of OSAHS are attributable to excess weight?
40-60%
How does lung volume influence airway collapse?
lung volumes influence the caudal traction on the pharynx
Obese individuals are at how many times at risk for OSAHS?
4x
10% weight gain is associated with a how many percent increase in AHI
> 30%
Even modest weight loss or weight gain can influence the risk and severity of OSAHS. However, the absence of obesity does not exclude this diagnosis.
true
factors that predispose men to OSAHS
android patterns of obesity
greater pharyngeal length
Prevalence of OSAHS among middle aged adults
2-15%
Prevalence of OSAHS among elderly
> 20%
Peak of OSAHS between ages 3 to 8 is due to?
lymphoid hypertrophy
Most common complaint of OSAHS
Snoring
What distinguishes OSAHS from paroxysmal nocturnal dyspnea, nocturnal asthma, and acid reflux with laryngospasm
Absence of Dyspnea
Frequent awakening or sleep disruption is more common among?
Women and older adults
Most common daytime symptom
excessive sleepiness
Gold standard for diagnosis of OSAHS
overnight Polysomnogram
tests that record only a few respiratory and cardiac channels commonly are used as a cost-effective means for diagnosing patients without significant comorbidity who have a high pretest probability of OSAHS.
Home sleep tests
Key physiological information collected during a sleep study for OSAHS assessment
breathing
oxygenation
body position
cardiac rhythm
additional: sleep continuity, sleep stages, limb movements, snoring intensity
defined as time from lights off to first sleep onset
sleep latency
defined as percentage of time asleep relative to time in bed
sleep efficiency
defined as the number of cortical arousals per hour of sleep
arousal index
pattern seen in an overnight BP monitoring with a the absence of the typical 10 mmHg fall of BP using sleep compared to wakefulness
non-dipping pattern
Cessation of airflow for >10s accompanied by persistent respiratory effort
obstructive apnea
cessation for airflow for 10s accompanied by absence of respiratory effort
central apnea
A ≥30% reduction in airflow for at least 10 s during sleep that is accompanied by either a ≥3% desaturation or an arousal
hypopnea
Partial obstruction that does not meet the criteria for hypopnea but provides evidence of increasing inspiratory effort (usually through pleural pressure monitoring) punctuated by an arousal
Respiratory effort-related arousal (RERA)
A partially obstructed breath, typically within a hypopnea or RERA, identified by a flattened or “scooped-out” inspiratory flow shape
Flow limited breath
Number of apneas plus hypopneas per hour of sleep
AHI
Number of apneas plus hypopneas plus RERAs per hour of sleep
Respiratory disturbance index (RDI)
Mild OSAHS
AHI of 5–14 events/h
Moderate OSAHS
AHI of 15–29 events/h
Severe OSAHS
AHI of ≥30 events/h
what is the inspiratory flow pattern of a patient with a patent airway
rounded and peaks in the middle
A partially obstructed airway exhibits what pattern
early peak followed by mid-inspiratory flattening, yielding a scooped-out appearance
Impact of CPAP in reducing 24h ambulatory BP averages how much?
2-4 mmHg
How many percent of patients with moderate to severe OSAHS report daytime sleepiness.
more than 50%
Patients with OSAHS symptoms have how much risk of occupational accidents?
2x increased risk
Optimum sleep duration
7-9h
Alcohol ingestion must be avoided within how many hours of bedtime?
within 3 hours
Beneficial effects on CPAP
BP Alertness Mood QOL Insulin sensitivity
CPAP with oral appliance reduces AHI by how much in 2/3 of individuals?
≥50%
Upper airway surgery for OSAHS is less effective than CPAP and is mostly reserved in 3 situations
Patients who snore
have mild OSAHS
cannot tolerate CPAP
Upper airway surgery is less effective in severe OSAHS and in obese patients.
What is the most common surgery of the upper airway fir OSAHS?
Uvulopalatopharyngoplasty
Enrolled patients for upper airway neuro-stimulation
- BMI ≤32 kg/m2
- moderate OSAHS
absence of complete - concentric pharyngeal collapse - unable to be treated successfully with CPAP
This is often caused by an increased sensitivity to pCO2, which leads to an unstable breathing pattern that manifests as hyperventilation alternating with apnea.
Central sleep apnea
Cheyne-Stokes respiration
crescendo-decrescendo breathing pattern occurring with prolonged circulation delay
This refers to a condition when CPAP particularly at high pressures induce central apnea
Complex Sleep Apnea
