Great Lakes Sleep Diagnostics - Glossary of Terms

Glossary of Terms

The amount of information we provide can be overwhelming. Therefore, we have developed a glossary of the common terminology used by sleep professionals. Please refer to this glossary if you should have any questions while exploring our website or reviewing the paperwork we have provided. This glossary will also be helpful when reviewing the results of your sleep study.

Airflow
Airflow is the amount of air moving in and out of the nose or mouth during breathing. This is sensed by the devices we place under the nose. There a number of different devices that we may use to measure the airflow.
Apnea
An apnea is an absence of breath, or the absence of airflow coming from the nose or mouth and/or absence of respiratory effort. We monitor for apneas with the airflow sensor placed under the nose, and the respiratory belts that measure breathing.
Arousal
An arousal is an interruption of sleep. Arousals may be associated with apnea, hypopnea’s (partial apneas}, leg movements, teeth grinding, or noise. When there are too many arousals, sleep is not maintained and is fragmented or broken-up.
Awake state
Non-sleep state, eyes open, alert.
Bi-Level Positive Pressure Ventilation
This is the same basic mechanical device as the C.P.A.P. except with two types of pressure. As with C.P.A.P. pressurized air is blown thru a hose into a mask that helps to splint the airways open. The splinting of the airway helps to eliminate most of the sleep disordered breathing and snoring. Bi-Level positive pressure ventilation is different than CPAP because it generates two completely separate pressures to aid in inspiration and exhalation. The higher pressure is called IPAP (inspiratory positive airway pressure) and assists during inhalation. The lower pressure is called EPAP (expiratory positive airway pressure) which is the expiratory pressure needed to splint the airway and eliminate apneas.
Bi-level is commonly used with individuals who are unable to tolerate high CPAP pressure, or for individuals who do not suffer from a total obstruction of the airway but experience a partial obstruction. Partial obstructions may limit the ability for complete gas exchange in the lungs, this is calles hypoventilation, or alveolar hypoventilation. Gas exchange in the lungs occurs between the alveoli and capillaries at the microscopic level.
Bradycardia
Low heart rate.
Bruxism
Grinding teeth
Cannula
Tubing placed under the nose to either deliver oxygen, read the values of exhaled carbon dioxide, or measure changes in pressure to determine airflow.
Central Apnea
This type of apnea (cessation of breathing) differs from obstructive apnea in that the patient exhibits no breathing effort during the period absent of airflow.
Continuous Positive Airway Pressure (C.P.A.P.)
A mechanical device which blows pressurized air thru a hose, into a fitted mask (patient interface device). The positive pressure delivered by the CPAP device helps to splint the airways open, thus eliminating sleep disordered breathing.
Electrode
An electrode is a wire with a small cup on the end of it. Electrode paste is placed in the wire. The paste helps the electrode make contact with the skin so that we can obtain the electrical activity of the brain (EEG), muscle movements, heart rate, etc. The wires or electrodes are placed on the patient to act as a conductor by receiving electrical impulses which are then sent to the computer and translated into information.
Electrocardiogram (ECG)
The ECG looks at the heart rate and for any abnormal heart rhythms. Atrial fibrillation is commonly associated with sleep apnea. Children will have more variability in their heart rate than adults.
Electroencephalogram (EEG)
The EEG refers to the channels that record brain waves to the computer. We use these channels to determine when sleep occurs, to differentiate sleep from wakefulness and to determine the different stages of sleep.
Electromyogram(EMG)
The EMG electrodes are placed on the chin and legs to determine chin tone or muscle movement. We use the information to look for teeth grinding (bruxism) or leg movements. The muscle tone of the chin also helps us when scoring the sleep study to determine REM sleep.
Electrooculogram (EOG)
Electrodes placed next to the eyes in order to pick up eye movements. We are able to determine REM or dream sleep when the EEG slows down and there are frequent eye movements.
Epoch
One page of the sleep study or 30 seconds.
End-tidal carbon dioxide (ETCO2)
This is used to measure the exhaled carbon dioxide during each breath. The value is usually measured at the nose with nasal prongs. This information is helpful in diagnosing sleep disordered breathing when there are not obvious episodes of apneas. ETCO2
First night affect
The effect of the sleep lab environment on the quality our guests sleep during the first night of recording. Sleep is usually reduced in quality compared to home.
Heart Rate
How fast the heart beats. The heart rate tends to change often in children.
Hypopnea (partial apnea)
A reduction in airflow of greater than 50% of the normal breath. To be “scored” these events must last 10 seconds or longer in adults, shorter events are often scored in infants and children due to the faster respiratory rates.
Hypersomnia
Excessive deep sleep, or lengthened sleep period.
Impedance
Is a way of measuring how well the electrode is connected to a patient and how well the electrode is functioning.
Montage
A specific arrangement by which the study is displayed for the technician.
Multiple sleep latency test (M.S.L.T.)
This study is performed after a regular nights sleep study. The M.S.L.T. is used to evaluate individuals who experience daytime sleepiness with no clear reason as to why. The study results are useful in diagnosing a condition called narcolepsy.
NREM sleep stages
For adult sleep, Stages 1, 2, 3 and 4 within the Sleep Period. For child sleep, Stages 1, 1/2, 2, 3, 3/4 and 4 within the Sleep period.
Obstructive Sleep Apnea
A diagnosis used for individuals who stop breathing during sleep due to an obstructed airway with continued respiratory effort.
Oxygen Saturation (O2)
This is read by the sensor placed on the finger, often called the “E.T. finger” because of the red light.
Polysomnography/polysomnogram (P.S.G.)
An overnight sleep study. A PSG uses the EEG, EMG, EOG, EKG, and respiratory variables to study an individuals sleep and breathing.
Pulse Oximeter(sao2)
The device used to measure the oxygen levels in a patients blood.
Rapid eye movements (R.E.M.s)
This occurs during REM sleep. We are able to determine that the child is dreaming and in REM sleep by looking for frequent eye movements.
REM sleep
Stands for Rapid Eye Movement. The Rapid Eye Movement stage is where we see all the eye movements, even though the rest of the body is totally relaxed. REM is the stage of sleep where dreaming occurs.
Respiratory effort
The amount of movement or effort your child uses to breath during the sleep study. We use the respiratory belts to watch for changes in effort. The belts are placed on the chest and stomach.
Respiratory events
These are periods of abnormal breathing during sleep. These may be apneas, partial apneas, or central apneas. We count all of these events during sleep in order to determine what type of treatment may be beneficial. To be identified and scored as a respiratory event an episode of reduced airflow must last 10 seconds or longer in adults, shorter events are often scored in infants and children due to the faster respiratory rates.
Sao2
This is read by the pulse oximeter and is the percentage of oxygen in the blood.
Sensor
An instrument used to measure an electrical signal and deliver the signal to the computer to be processed and changed to a recording that we are able to use to evaluate sleep and breathing.
Sleep Efficiency
This is the percentage of actual sleep time during the sleep study recording. This is used to evaluate the quality of the sleep on the night of the sleep study.
Sleep Architecture
States and cycles of sleep depicted as a whole study.
Sleep cycle
Is a complete cycle of sleep stages that happens about every 90 minutes until you are awake. Most children experience about 4 or 5 sleep cycles during the night. Sleep disordered breathing will often interfere with the sleep cycles.
Sleep diary
An important tool used for daily entries of the patient’s activities, bedtimes and naps. It is recommend that a sleep diary be recorded for at least two weeks prior to the sleep study. This tool is helpful and an important tool to help diagnose problems that could otherwise be missed.
Sleep Disordered Breathing
A general term used to describe abnormal breathing patterns during sleep.
Sleep Hygiene
Following a specific routine before bedtime that is conducive to good sleep. Examples are a regular bedtime, no T.V. or video games in the bedroom, low noise levels etc.
Spontaneous Arousal
An arousal from sleep that is not associated with a respiratory event, increased muscle tone, or environmental interference.
Stage 1 sleep
Occurs at sleep onset and after arousal from other sleep stages. This is a very light stage of sleep.
Stage 2 sleep
Occurs after stage one sleep. It is a light stage of non REM sleep. The majority of sleep for adults and older children is spent in stage 2. You can be easily awakened while in stage 2.
Stage 3 and 4 sleep
Are deep stages of sleep. Stage 4 is the deepest stage of all. Both stages are non REM and are often referred to as slow wave sleep. It is very hard to awaken someone from these stages. Arousals from stage 4 sleep may be associated with sleep walking, sleep terrors and confusion.
Tachycardia
Heart rate that is above the normal rhythm for age, sleep/wake state and activity.
Titration
This is when the technician monitors the patient very closely and raises the air pressure of the C.P.A.P or Bi-Level to eliminate apneas and snoring.
Total sleep time (T.S.T.)
The sum of all REM and NREM sleep time during the study, excludes time awake.

Great Lakes Sleep Diagnostics | 44968 Ford Rd. Suite G | Canton, MI 48187
Phone: 734-335-6662 | Fax: 734-335-6618