By
Lucy suliman
Sleep related breathing
disorders defintions
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Apnea:
Apnea is the cessation, or near cessation, of
airflow for 10 seconds. Oronasal thermal
sensor (or alternative) drops by ≥90% of
baseline.
Duration ≥ 10 sec. At least 90% of events
duration must meet apnea amplitude
reduction criteria .
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Obstructive apnea
An obstructive apnea occurs when airflow
is absent or nearly absent, but ventilatory
effort persists. It is caused by complete,
or near complete, upper airway
obstruction.
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Central apnea
A central apnea occurs when both airflow
and ventilatory effort are absent Breathing
cessation is proven by an absence of
diaphragmatic activation, measured by
electromyography (EMG).
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Mixed apnea
During a mixed apnea, there is an interval
during which there is no respiratory effort
(ie, central apnea pattern) and an interval
during which there are obstructed
respiratory efforts .The central apnea
pattern usually precedes the obstructive
apnea pattern during mixed apnea
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Hypopnea
Hypopnea is a reduction of airflow to a degree that is
insufficient to meet the criteria for an apnea.
The most recent definition, endorsed by the American
Academy of Sleep Medicine, recommends that hypopnea
be scored when all of the following four criteria are met:
Airflow decreases at least 30 percent from baseline
There is diminished airflow lasting at least 10 seconds
at least 4 percent oxyhemoglobin desaturation
Associated with arousal
or
Airflow decreases at least 50 percent
from baseline
There is diminished airflow lasting at
least 10 seconds
 3 percent oxyhemoglobin desaturation
or an arousal
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Respiratory effort related arousals —
Respiratory effort related arousals
(RERAs) exist when there is a
sequence of breaths that lasts at least
10 seconds, is characterized by
increasing respiratory effort or
flattening of the nasal pressure
waveform
leads to an arousal from sleep
does not meet the criteria of an
apnea or hypopnea
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Hypoventilation
Hypoventilation during sleep is defined as
an increase in the arterial carbon dioxide
(PaCO2) of 10 mm Hg during sleep
(compared with an awake supine value)
that lasts at least 25 percent of the sleep
time.
Directly measuring the pCO2 in an arterial
blood gas during a sleep study is optimal,
but impractical.
Transcutaneous CO2 measurements and
expired end tidal CO2 are alternatives .
Polysomnography
indices
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Apnea index
The apnea index (AI) is the total number of
apneas per hour of sleep
Apnea-hypopnea index — The apnea–
hypopnea index (AHI) is the total number of
apneas and hypopneas per hour of sleep.
The AHI is most commonly calculated per
hour of total sleep.
Respiratory disturbance index
The respiratory disturbance index (RDI) is
the total number of events (eg, apneas,
hypopneas, and RERAs) per hour of sleep.
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Desaturation — Oxygen desaturation is a
frequent consequence of apnea and
hypopnea. Several measures are used to
quantify the severity of desaturation and
should be included in polysomnography
report .
Oxygen desaturation index (ODI)
This is the number of times that the oxygen
saturation falls by more than 3 or 4 percent
per hour of sleep Minimum levels
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Arousal index
The arousal index (ArI) is the total
number of arousals per hour of sleep.
It is generally lower than the AHI or
RDI because approximately 20 percent
of apneas or hypopneas are not
accompanied by arousals
syndromes of sleep related
breathing disorders
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Obstructive sleep apnea syndrome
Obstructive sleep apnea syndrome encompasses
obstructive sleep apnea (OSA) in adults and OSA in
children. OSA in adults is defined as either :
More than 15 apneas, hypopneas, or RERAs per
hour of sleep (ie, an AHI or RDI >15 events/hr) in
an asymptomatic patient
OR
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More than 5 apneas, hypopneas, or RERAs per hour
of sleep (ie, an AHI or RDI >5 events per hour) in a
patient with symptoms (eg, sleepiness, fatigue and
inattention) or signs of disturbed sleep (eg, snoring,
restless sleep, and respiratory pauses).
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Central sleep apnea syndrome
Central sleep apnea syndrome (CSAS) can
be:
idiopathic (eg, primary central sleep
apnea [CSA])
secondary. Examples of secondary CSAS
include Cheyne-Stokes breathing, CSA due
to high altitude periodic breathing, CSA
due to a medical condition, and CSA due
to a drug or substance. More than 75
percent of events should be central to
qualify for this syndrome category.
Complex Sleep Apnea (CompSA)
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CompSA consists of all or
predominantly obstructive apneas
which convert to all or predominantly
central apneas when treated with a
CPAP or bilevel devices
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Cheyne-Stokes breathing — Cheyne-Stokes
breathing refers to a cyclic pattern of crescendodecrescendo tidal volumes and central apneas,
hypopneas, or both. It is commonly associated
with heart failure or stroke.
Hypoventilation syndromes — Patients with a
hypoventilation syndrome generally have mild
hypercarbia or elevated serum bicarbonate
levels when awake, which worsen during sleep.
Two hypoventilation syndromes:
congenital central hypoventilation syndrome
(CCHS)
obesity hypoventilation syndrome (OHS),
Cheyne-Stokes breathing
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Obstructive sleep apnea :(OSA) is a disorder that is characterized by
obstructive apneas and hypopneas caused
by repetitive collapse of the upper airway
during sleep.
The diagnosis should be considered
whenever a patient presents with risk
factors or clinical manifestations that are
compatible with OSA.
RISK FACTORS :
 obesity.
 craniofacial abnormalities.
 upper airway soft tissue abnormalities.
 Potential risk factors include:
heredity,smoking, nasal congestion, and
diabetes .
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EPIDEMIOLOGY
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26 percent of adults are at high risk
for OSA .
20 percent if defined as an apnea
hypopnea index greater than five
events per hour .
2 to 9 percent is defined as an AHI
greater than five events per hour
accompanied by at least one symptom
that is known to respond to treatment
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Age :The prevalence of OSA increases from 18
to 45 years of age.
There is a two- to three-fold higher
prevalence among individuals who are 65
years and older, compared to those who
are 30 to 64 years old.
Grades of OSA
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Mild :AHI between 5 and 15 events per hour
Moderate:an AHI between 15 and 30 events per
hour
Severe:AHI greater than 30 events per
hour, as well as an oxyhemoglobin
saturation below 90 percent for more than
20 percent of the total sleep time
Diagnosis of OSA
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History
Physical examinations
laboratory
Subjective questionnaire:Berline questionnair
Epworth Sleepness scale
Polysomnography.
Mallampati airway cassification
modified Mallampati
Physical examination: Mallampati score as an independent predictor of obstructive
sleep apnea. Sleep 2006
Laboratory
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1)protinuria — Less than 10 percent of
patients with OSA have proteinuria
2) Hypercapnia — Although uncommon in
OSA alone, awake hypercapnia (and
hypoxemia) may be present if obesity
hypoventilation syndrome coexists
3)Hypothyroidism — OSA can be caused or
exacerbated by hypothyroidism
Imaging Studies
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lateral cephalometry,
endoscopy,
fluoroscopy,
CT scanning,
MRI.
Epworth sleepiness
scale:
The chance to doze off or fall asleep in the following
situation:
1-sitting and reading
2- watching TV
3- sitting inactive in public place
4-as a passenger in a car for an hour without a
break
5-lying down to rest in the afternoon when
circumstances permit
6-sitting and talking to someone
7- sitting quietly after a lunch without alcohol.
8- in a car while stopped for few minutes in traffic
Berline questionnaire
Cardiovascular effects of
obstructive sleep apnea
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SYSTEMIC HYPERTENSION
PULMONARY HYPERTENSION
CORONARY ARTERY DISEASE
CARDIAC ARRHYTHMIAS
Cerebral stroke.
polysomnographic finding
of OSA
EEG FINDINGS
Increased stage N1
Reduced stage N3
Reduced stage R (REM sleep)
Increased respiratory arousals
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RESPIRATORY FINDINGS
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Snoring
Obstructive, mixed apneas, and central
apneas
Obstructive hypopneas
AHI: mild 5 to <15/hr, moderate 15–30/hr,
severe > 30/hr
AHI supine > 2 × AHI nonsupine – postural
OSA
AHI REM > AHI NREM common
Apnea duration REM > NREM
ARTERIAL OXYGEN
DESATURATION
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Lowest SaO2 during REM sleep
Longest REM periods in the early
morning hours typically have the worst
desaturation
CYCLIC VARIATION IN
HEART RATE
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Slowing of heart rate at apnea onset
and speeding at event termination.
diagnostic criteria of OSA
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1) an obstructive respiratory disturbance
index (RDI) greater than 15 events per
hour.
2) an obstructive RDI between 5 and 14
events per hour that is accompanied by
daytime sleepiness, loud snoring, witnessed
breathing interruptions, or awakenings due
to gasping or choking.
Academy of Sleep Medicine: The AASM Manual for Scoring
of Sleep and Associated Events: American Academy of Sleep Medicine, 2007.
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Types of Polysomnography
Full-night, attended, in-laboratory
polysomnography (PSG) is considered the goldstandard diagnostic test for OSA. It involves
monitoring the patient during a full night's sleep
Patients who are diagnosed with OSA and
choose positive airway pressure therapy are
subsequently brought back for another study,
during which their positive airway pressure
device is titrated
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Split-night
attended, in-laboratory polysomnography is
similar, except the diagnostic portion of the
study is performed during the first part of the
night only. Those patients who are diagnosed
with OSA during the first part of the night and
choose positive airway pressure therapy can
have their positive airway pressure device
titrated during the second part of the night
Portable monitoring
There are a variety of devices that are used for
in-home, unattended, portable monitoring. M
Indications for treatment
1.
2.
3.
respiratory disturbance index (RDI)
greater than 15 events per hour
an obstructive RDI between 5 and 14
events per hour that is accompanied by
daytime sleepiness, loud snoring,
witnessed breathing interruptions, or
awakenings due to gasping or choking.
The AHI is greater than five events per
hour and the patient performs mission
critical work (eg, airline pilot, bus driver)
4.The frequency of respiratory effort related
arousals (RERAs) is abnormal in a patient
with subjective or objective daytime
sleepiness, even if the AHI is five events
per hour or less
5.The AHI is greater than five events per hour
and the patient has excessive daytime
sleepiness alone that has been objectively
measured and confirmed by an abnormal
multiple sleep latency test, maintenance of
wakefulness test
Choosing a therapy
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American Academy of
Sleep Medicine
recommends offering
positive airway pressure
therapy to all patients who
have OSA
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The choice of an OSA-specific
therapy:-
positive airway pressure,
 an oral appliance,
 upper airway surgery.
 Medical treatment.
depends on the severity of the OSA .
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severe OSA (AHI >30 events per
hour and/or severe clinical
sequelae
we use positive airway pressure as
first-line therapy. This is based on the
variable efficacy of oral appliances in
this patient population.
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For patients with mild or moderate OSA
(AHI ≤ 30 events per hour with severe
clinical sequelae
we prefer positive airway pressure to an oral
appliance because it is superior at reducing the
frequency of obstructive events.
In contrast, for patients with mild or
moderate OSA without severe clinical
sequelae
we initiate an oral appliance rather than positive
airway pressure. This is based on our
recognition that most patients prefer an oral
appliance
and both modalities have a similar effect on
symptoms
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surgical therapy
when positive airway pressure or an
oral appliance is declined, ineffective
(after at least a three month trial of
therapy), or not an option
For patients whose OSA is due to a
surgically correctable obstructing
lesion, surgical resection of the
obstructing lesion is first-line therapy
BEHAVIOR MODIFICATION
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Weight loss
Sleep position
Alcohol avoidance
Medication avoidance