OSA Terms
Following are some terms for OSA. These terms were researched and submitted
by Carolyn, a Sleepnet forum friend. Hope they are helpful.
apnea - defined as the cessation of airflow at the nostrils and mouth
for at least 10 seconds. Literally means "no breath."
apnea index (AI) - the number of apnea events per hour. A measure of
the severity of sleep apnea.
apnea plus hypopnea index (AHI) - the number of apneas and hypopneas
in an hour of sleep. Criterion: 5 to 20 = mild; 21 to 50 = moderate; above
51 = severe.
central apnea - absence of both airflow and inspiratory effort. Apnea
caused by irregularity in the brain's control of breathing.
excessive daytime sleepiness or somnolence - a subjective report of
difficulty in maintaining the awake state, accompanied by a ready entrance
into sleep when the individual is sedentary; may be quantitatively measured
by use of subjectively defined rating scales of sleepiness.
hypercapnia - too much carbon dioxide in the blood. Elevated carbon
dioxide level in blood.
hypersomnia - excessive or prolonged sleep. Sometimes associated with
difficulty in awakening or sleep drunkenness.
hypopnea - shallow breathing in which the air flow in and out of the
airway is less than half of normal. Usually associated with oxygen
desaturation.
hypoxemia - an abnormal lack of oxygen in the blood in the arteries.
Symptoms of acute hypoxemia are the patient turning blue, restlessness,
stupor, coma, increased blood pressure, too-rapid heart beat, and an initial
increase in heart output that later falls, resulting in low blood pressure
and irregular heart beat or heart stoppage. Chronic hypoxemia stimulates red
blood cell production by the bone marrow, leading to an excess of red cells.
Hypoxemia caused by decreased oxygen pressure in the blood or too little
oxygen intake improves with oxygen therapy. Hypoxemia resulting from shunting
of blood from the right side of the heart to the left side of the heart
without exchange of gases in the lungs is treated with bronchial hygiene and
breathing therapy.
laser assisted uvulopalatoplasty (LAUP) - may eliminate or decrease
snoring but has not been shown to be effective in treating sleep apnea.
mandibular maxillary osteotomy and advancement (MMOA) - a procedure
developed for those patients with retrolingual obstruction, or those
patients with retropalatal and retrolingual obstruction who have not
responded to CPAP and uvulopalatopharyngoplasty (UPPP).
micro-arousal - partial awakening from sleep of which the sleeper is
unaware.
micro-sleep - a period lasting up to a few seconds during which the
polysomnogram suddenly shifts from waking characteristics to sleep and
external stimuli are not perceived; associated with excessive daytime
sleepiness and automatic behavior, which are symptoms of DOES. Or a lapse
from wakefulness into sleep that lasts just a few seconds, typically
experienced by sleep-deprived persons.
mixed (sleep) apnea - interruption in breathing during sleep which
begins as a central apnea then becomes an obstructive apnea.
multiple sleep latency test (MSLT) - a series of measurements of the
interval from "lights out" to sleep onset that is utilized in the assessment
of excessive daytime sleepiness. Subjects are allowed a fixed number of
opportunities to fall asleep during their customary awake period. Long
latencies are helpful in distinguishing physical tiredness or fatigue from
true sleepiness. Or measures how sleepy you are by observing how long it
takes you to fall asleep.
NREM or non-REM sleep - quiet sleep, slow-wave sleep; about 80 percent
of sleep; characterized by slower and larger brainwaves and little or no
dream behavior.
obstructive apnea - (1) a cessation of airflow (10 seconds) in the
presence of continued inspiratory effort. Or apnea caused by blockage of the
airway; (2) cessation of breathing during sleep, due to a mechanical
obstruction, such as a semi-collapsed trachea, tongue relaxed to back of the
throat, or a large amount of tissue in the uvula area.
O2 - Chemical symbol for oxygen. Criterion lowest percent
O2 saturation: Greater than 85% = mild; 80% to 85% = moderate;
less than 80% = severe.
PO2 - partial pressure of oxygen (O2) in the
blood. Any value for PO2 above 60 is usually considered a safe
level; lower than 60 indicated hypoxemia and potential danger for the
patient.
polysomnogram - the continuous and simultaneous recording of
physiological variables during sleep, i.e., EEG; EOG; EMG -- these are the
three basic stages scoring parameters; EKG; respiratory air flow;
respiratory excursion; lower limb movement; and other electrophysiological
variables.
pulse oximetry - a non-invasive measure of one's oxygen saturation;
that is the amount of oxygen saturated in the hemoglobin in terms of
percentage. This is not as accurate as the values obtained from an arterial
blood gases (ABG) test and should only be used as a gauge of oxygenation.
Normal ranges are between 95 to 100%. Supplemental oxygen is not generally
instituted unless SaO2 is less that 88 to 90% at rest.
REM sleep (rapid eye movement sleep) - sleep characterized by the
active brainwaves, flitting motions of the eyes, and weakness of the muscles;
most dreaming occurs in this stage, which accounts for about 20% of sleep in
adults.
sleep - a state marked by lessened consciousness, lessened movement of
the skeletal muscles, and slowed-down metabolism. People normally sleep in
patterns that follow four definite, gradual stages. These four stages make up
three-fourths of the periods of typical sleep and are called, as a group,
nonrapid eye movement (NREM) sleep. The remaining time is usually occupied
with rapid eye movement (REM) sleep. The REM sleep periods, lasting from a
few minutes to half an hour, alternate with the NREM periods. Dreaming occurs
during REM time. Individual sleep patterns change throughout life because
daily need for sleep gradually diminish from as much as 20 hours a day in
infancy to as little as 6 hours a day in old age. Infants tend to begin a
sleep period with REM sleep, whereas REM activity usually follows the four
stages of NREM sleep in adults.
sleep hygiene - the conditions and practices that promote continuous
and effective sleep. These include regularity of bedtime and arise time;
conformity of time spent in bed to the time necessary for sustained and
individually adequate sleep (i.e., the total sleep time sufficient to avoid
sleepiness when awake); restriction of alcohol and caffeine beverages in the
period prior to bedtime; employment of exercise, nutrition, and environmental
factors so that they enhance, not disturb, restful sleep.
sleep stage NREM (NREMS) - the major sleep state apart from REMS;
comprises sleep stages 1 through 4, which constitute areas in the spectrum of
NREMS "depth" or physiological intensity.
sleep stage 1 (NREMS stage 1) - a stage of NREMS sleep that ensues
directly from the awake state. Its criteria consist of a low voltage EEG with
slowing to theta frequencies, alpha activity less than 50%, EEG vertex spikes,
and slow rolling eye movements; no sleep spindles, K-complexes, or REMS.
Stage 1 normally assumes 4 to 5% of total sleep.
sleep stage 2 (NREMS stage 2) - a stage of NREM sleep characterized
by the advent of sleep spindles and K complexes against a relatively low
voltage, mixed frequency EEG background; high voltage delta waves may
comprise up to 20% of stage 2 epochs; usually accounts for 45 to 55% of total
sleep time.
sleep stage 3 (NREMS stage 3) - a stage of NREM sleep defined by at
least 20% and not more than 50% of the period consisting of EEG waves less
than 2 Hz and more than 75 uV (high amplitude delta waves); a "delta" sleep
stage; with stage 4, it constitutes "deep" NREM sleep; and often combined
with stage 4 into NREMS stage 3/4 because of the lack of documented
physiological differences between the two; appears usually only in the first
third of the sleep period; usually comprises 4 to 6% of total sleep time.
sleep stage 4 (NREMS stage 4) - all statements concerning NREMS stage
3 apply to stage 4 except that high voltage, slow EEG waves cover 50% or
more of the record. NREMS stage 4 usually takes up 12 to 15% of total sleep
time. Somnambulism, sleep terror, and sleep-related enuresis episodes
generally start in stage 4 or during arousals from this stage. See Sleep
stage 3.
sleep stage REM (REMS) - the stage of sleep (e.g., state of the CNS)
found in all mammal studies, including man, in which brain activity is
extensive, brain metabolism is increased, and vivid hallucinatory imagery,
or dreaming occurs (in humans). It is also called "paradoxical sleep"
because in the face of this intense excitation of the CNS and presence of
spontaneous rapid eye movements, resting muscle activity is suppressed. The
EEG is a low voltage, fast frequency, nonalpha record. Stage REMS is usually
20 to 25% of total sleep time.
titration - a progressive, stepwise increase in CPAP pressure applied
during a polysomnogram to establish the optimal treatment pressure.
uvulopalatopharyngoplasty - (1) operation performed on the throat to
treat snoring and sleep apnea: abbreviated as UPPP, UPP, or UP3; (2) UPPP is
an accepted means of surgical treatment for OSA, but is curative in less than
50% of patients. Scientific evidence suggests that UPPP works best in
retropalatal and combination retropalatal and retrolingual obstruction.