For Sleep Techs

Sinusoidal EEG activity in the range of 8 - 13 Hz highest in the occipital channel. The wave-form is smooth and regular. The amplitude of the signal decreases when the eyes are open. Must be distinguished from alpha frequency activity, which is 8 - 13 Hz but may be sharp and irregular and my not be most prominent in the occipital channel. Alpha frequency activity may not change with eye opening.

Bursts of leg muscle activity coming first from one leg and then the other. There must be at - least 4 muscle bursts The minimum frequency is Hz. (one burst every other second) and the maximum frequency is 3 Hz (3 bursts per second).

The magnitude of a signal, measured from the top most point (zenith) to the lowest point (nadir). For electrical signals like the EEG, the measurement unit is usually volts or portions of volts. A microvolt (uV) is 1/1,000 volt. In sleep recordings, amplitude is the height of the signal on the vertical (Y) axis.

A pause in breathing during sleep. An apnea must last at least 10 seconds in adults and 2 missed breaths in children. Apneas are defined by at least a 90% drop in the amplitude of the thermal sensor signal.

An awakening or lightening of sleep. The criteria for scoring an arousal are an abrupt shift in EEG frequency lasting at least 3 seconds, with at least 10 seconds of stable sleep before the event. Sleep spindles do not count in the scoring of arousals. For arousals from R, the chin EMG must increase for at least 1 second in addition to the abrupt shift of EEG frequency.

A period with no cardiac electrical activity and no cardiac output or blood flow. For ages 6 and up the period must last 3 seconds or more Atrial fibrillation

The most common cardiac arrhythmia. Normally, electrical impulses in the heart are generated by the sino-atrial node. In atrial fibrillation, impulses start in the atria and pulmonary veins. Conduction through the ventricles is irregular, leading to an irregular heart rate. Atrial fibrillation is associated with congestive heart failure and increased risk of stroke.

An abnormally slow heart rate. During waking, a heart rate slower than 60 beats per minute is considered abnormal. The heart rate is usually slower during sleep, and a limit of 40 beats per minute- is used to define bradycardia during a polysomnogram.

Tooth grinding. Bruxism can cause tooth damage and excessive wear. It can occur as chewing movements or clenching of the jaw, or as both. It is common during sleep and during brief arousals from sleep.

A type of apnea with no airflow and no effort to breathe. Central apneas often occur at sleep onset and at high altitude. Patients with Cheyne Stokes breathing often have periods of central apnea. Central apneas last at least 10 seconds in adults and at least 20 seconds in children.

A pattern of breathing in which the volume and rate of breathing increases (crescendo) and breathing decreases (decrescendo) with a cycle length of about 60 seconds. It is most often associated with heart failure, but can occur with any problem causing damage to the respiratory centers such as stroke or brain tumor.

When used in polysomnography, distribution means the location on the scalp that is the origin of an EEG signal. In recordings using a single reference electrode (such as the standard polysomnogram montage) this is determined by the amplitude of the signal. For example, the highest amplitude of slow wave activity is M the frontal channel. This is taken to mean that the signal comes from the frontal lobes.

The EEG activity in children that is the same as alpha rhythm in adults. Like alpha rhythm, the activity usually goes away with eye opening. It is seen in infants 3 to 4 months post term at 3.5 to 4.5 Hz, at 5 to 6 Hz by 5 to 6 months and at 7.5 to 9.5 Hz at 3 years of age. It should be in the alpha frequency range in all children by 12 years of age.

The duration of a signal is the time it takes for a full cycle ,of a waveform to occur. The duration of a signal is the inverse of the frequency (1/frequency). The duration of a 3 Hz signal is
I/3 or 0.33 seconds. The AASM Manual uses duration criteria for some signals (for example,
K complexes last more than 0.5 seconds) and frequency criteria for others (eye blinks occur
at a rate of 0.5 to 2 Hz).

A heart beat that does not originate at the sino-atrial node. These can be premature ventricular beats (coming from the ventricles) or premature atrial contractions (coming from the atria).
When they occur one at a time they are not considered significant.