Sleep Studies
Lecture by Elizabeth Kelley Buzbee AAS,
RRT-NPS, RCP
Read: Egan’s
Chapter 27 Disorders of Sleep page 587-600
Read: Wilkins’
Chapter 18 Assessment of Sleep and Breathing
Other References:
George Burton’s Respiratory Care
Sleep disorders
are a serious problem because sleep deprivation is tied to increased accidents.
Some studies have compared sleep deprived persons with intoxication and found
the resulting accident rates compatible. Fatigue is associated with 57% of
truck driver accidents. [
1.
Describe normal sleep. List the normal sleep stages. [page 406 Wilkins]
Normal
sleep averages 8 hours a day*. Normal sleep is characterized by alterations
between two types of sleep every 60 to 90 minutes
a.
Non-REM sleep: non-rapid
eye movement sleep
i. Has 4 stages:
ii. first the patient goes into stage I in which he feels drowsy and
his EEG 8-12 alpha waves
iii.
Within minutes he moves
into stage 2 in which his EEK shows sleep spindles and K complexes [Theta
waves]. This is a deeper level of sleep and this is the predominate stage of
NREM sleep
iv.
Quickly goes into stages 3
and 4 characterized by slow-wave sleep [delta waves]. There are more delta
waves in 4 than in 3. It is difficult to arouse someone who is at that level of
sleep
v. after 60-90 minutes of non-REM sleep the
patient moves into REM sleep
2.
What are the Vital Signs during non-REM sleep? Respiratory rate slows and PaC02 rises 3-7
mmHg [
a.
REM sleep: rapid eye
movement sleep
i. Has slow low voltage random waves with saw
tooth
ii.
This is where we dream
iii.
He rotates in and out of REM sleep about 5 times a night. Early in the evening
REM sleep may only be 5 minutes long, but toward the morning, REM sleep can last
as long as 30-60 minutes
iv.
In adults and kids, REM sleep accounts for only 20%-25% of all sleep, in
newborns this REM sleep lasts 55%-80% of the time.
3.
What are the Vital signs during REM sleep? Because the patient is
dreaming at this time, skeletal muscles are so relaxed that a partial state of
paralysis results. Respiratory efforts are chaotic as response to hypercapnia
and to hypoxia are blunted.
The patient is at most risk for upper
airway obstruction and for hypoxemia during REM sleep
Heart
rates are variable and the person is most at risk for cardiac arrhythmias at
this point in sleep.
Blood
pressure tends to rise higher than during N-REM sleep
4.
Define Sleep apnea. List the three types of Sleep apnea. Compare these types of
sleep apnea.
a.
In adults, a cessation of
air flow for 10 seconds or more is called apnea [Wilkins, Burton] while a mere
reduction of airflow by 50% is hypopnea.
b.
A normal adult male can
have as much as 7 apneas/8hrs while women only have 2/8 hour. Needless to say
they will be asymptomatic. A diagnosis of sleep apnea is the presence of 5 apnea/hour. This can be discovered with an over-night
sleep study called a polysomnograph
c.
There are three types of
sleep apnea
i. Obstructive sleep apnea in which the problem is upper airway
occlusion during REM sleep. This is the most common sleep apnea with 2% of the
adult population having OSA
1.
During the polysomnograph study the patient will be seen to have no gas flow
but the chest continues to rise and fall.
2.
the majority of OSA happens during REM sleep
3. Central
sleep apnea in which the
patient suffers some CNS disturbance so that he fails to recognize or respond
to hypercapnia or hypoxia. Only 10% of folks with sleep apnea have central
sleep apnea
4.
during the polysomnograph study the patient will be
seen to have no air flow because the chest failed to rise and fall
5.
the majority of central sleep apnea happens during
transitions between awake to sleep during stage I of N-REM sleep
ii. Mixed obstructive and central apnea. In most
cases of mixed, the patient suffers Central sleep apnea followed by upper
airway occlusion.
1.
during the polysomnograph study the patient will first be seen to have no air
flow because the chest failed to rise and fall followed by chest wall movement
without air flow
5.
List the signs and symptoms of obstructive sleep apnea. Identify high risk
patients for this disorder. Identify high risk patients for this disorder.
a.
s/s of OSA: On
polysomnograph the patient will be seen to have a cessation of sleep that will
last for 20-30 seconds accompanied by a desaturation of 5%. If the patient has
a history of COPD, or cardiac problems this desaturation could be as much as a
50% drop. He will have an increase in BP with a decrease in CO with both
resolving as soon as breathing returns.
i. There will be a history of
cycles of apnea followed by arousal. Frequently the sleeping partner will
notice the problem first
ii.
With moderate to severe OSA, there will be a history of frequently falling
asleep in the daytime when he relaxes such as in front of the TV.
iii.
Memory loss, irritability, depression, poor sexual function
iv.
Tends to happen in the supine position and in some will be corrected by
positional changes: Positional Sleep Apnea
v. 33% of OSA patient have an
underlying HTN with spikes in the blood pressure in the AM.
vi. 36% will have a history of
morning headaches from hypercapnia
vii.
PVC and other cardiac arrhythmias—even short astyole is common
viii.
Bedwetting [enuresis] is common
ix.
Automatic behavior in which they act without knowing
what they are doing
b.
Who is at risk for OSA? Middle-aged
to elderly males, who are obese, who have short necks with a history of
snoring. History of alcohol use is significant. They frequently don’t know they
have a problem
i. On PE, you will find the uvula to be
red & swollen from being scrapped on the tongue all night when the airway
collapses. This will increase his gag reflex. You may also see airway
malformations, enlarged tonsils, or a deviated septum.
ii.
Might have a large tongue
or a small jaw
6.
List the signs and symptoms of central sleep apnea.
a.
Same basic symptoms of interrupted sleep
b. tend
to complain about insomnia more.
7.
Identify high risk patients for this disorder. Are older, snore only lightly, aren’t
overweight. Frequently have some underlying medical problem that accounts for
the apnea:
a.
History of damage to the medulla
b. History
of polio, Muscular Dystrophy or Myasthenia Gravis
c.
Cheyne-Stokes respirations associated with CHF are not considered a
central sleep apnea because the patient’s CO is down which creates a lag in
recognizing hypoxia. In Central sleep apnea the problem is neural not
circulation
8.
List the signs and symptoms of mixed sleep apnea.
a.
Same basic symptoms of interrupted sleep
9.
Identify high risk patients for this disorder.
10.
Discuss the link between COPD and sleep apnea.
a.
While there aren’t more
COPDers with sleep apnea than not, it does complicate their case. Because they
already have compromised ABGs the normal changes at night are more serious
b.
When they have
desaturations, arrhythmias and hypoxic episodes they are more serious
c.
They already suffer
increased RAW so decreased RAW at night can get worse
11.
Describe the sleep study. What parameters are measured? A PSG study consists of multiple channel
recorders attached to various wires to measure the following parameters:
a.
upper chest muscle action: EOG
b. abdominal
action: EOG
c.
EEG to determine sleep stages
d. EKG
to follow heart rates and rhythms
e.
respiratory rates
f.
airflow at the mouth and nose uses thermistor
g. Sp02:
ear pulse ox
h. eye
movement: EOG
i.
chin motion : EOG
j.
leg movement: EOG
12.
When is a polysomnograph indicated? According
to the AARC guidelines
a.
a person with cor
pulmonale whose daytime Pa02 is above 55 mmHg needs to be assessed at night.
b.
Anyone with s/s consistent
with sleep deprivation, and sleep apnea need to be checked out.
c.
Anyone with nocturnal
cardiac arrhythmias
What
pre-test screening is required? because
sleep needs vary so widely between one person and the next and because feelings
of insomnia are subjective, a study of a persons’ daylight alertness, a
multiple sleep latency test MSLT may be done to document that the loss of sleep
is effecting the patient in a negative way. MSLT can also rule out narcolepsy.
12
lead EKG for underlying cardiac problems & to rule out cor pulmonale
The
patient’s drug or ethanol use needs to be established with interviews.
Blood
work such as thyroid levels need to be done to rule out hypothyroidism which
will decrease entire metabolic rate.
13.
What is an Apnea Index? Apnea/total hours of sleep. If the patient only suffers hypopnea then
it is hypopnea/hours of sleep. An Apnea index of 5/hr is diagnostic of sleep
apnea, an Apnea Index of more than 20 is associated with a high mortality
14.
Describe the findings associated with OSA on the sleep study graph
a.
On the PSG reading, the oral and nasal thermistors
show zero flow rate while the chest wall and the
abdomen show continued action. The Sp02 drops sharply after the flow stops
b. This
should happen during REM sleep
15.
Describe the findings associated with central sleep apnea on the sleep study
graph.
a.
On PSG the chest and abdomen stop moving, then the air flow stops then the Sp02
drop a bit less.
b.
This should happen close
to the transitional going in or out of stage I of N-REM sleep
16.
Describe the findings associated with mixed sleep apnea on the sleep study
graph
a.
First you will have a central sleep apnea pattern, the airflow will stay down
and the chest wall starts up again. The Sp02 drop will be moderate to severe
17.
Discuss the treatments for OSA:
a.
Change ethanol or drug
abuse
b.
Loss weight
c.
If positional sleep apnea,
change to sleeping on the side
d.
Start CPAP while repeating
PSG and alter settings until sleep apnea resolves
e.
Start BiPap & monitor
with PSG
f.
Consider surgery on the upper airways. Only works in 20-50%
g. Consider
tracheostomy. Works for everyone, but has its own
drawbacks
18.
Central Sleep Apnea
a.
Diagnosis and treat underlying cause if possible
b. Position
change oddly enough can help some with CSA
c.
Low flow 02
d. CPAP
or BiPap
e.
Medications have not been found to help
f.
Consider tracheostomy and nocturnal ventilation
g. Consider
diaphragmatic pacing
19.
mixed sleep apnea.
a.
Treat the predominate apnea