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Polysomnography

Polysomnography is a sleep study that measures multiple physiologic parameters during the stages of sleep. The study is generally performed at night (in which case it is referred to as a nocturnal polysomnogram) and is designed to evaluate a typical sleep period for the patient undergoing evaluation.

A polysomnogram is ideally performed in a setting supervised by a technician to assure that high quality signals are being received by the polygraph. These studies are usually performed in a sleep center because home studies conducted in an unattended fashion may have technical limitations that make interpretation difficult.

The technician will perform a "hook up" that will involve placing anywhere between 12 and 20 wires on the body with either an adhesive material or attachment belts. Most studies are designed to measure physiologic parameters that include:

1. Electroencephalogram (EEG) to define the total sleep time and the different stages of sleep that may represent problem stages.

2. Measurements of eye movements to assess the presence of rapid eye movement sleep.

3. A measurement of airflow that will be obtained through the region of the mouth and nose.

4. Gauges over the chest and abdomen to measure respiratory effort.

5. Muscle activity (EMG) measured over the legs or arms.

6. Oximetry to assess saturation of oxygen throughout the study.

7. EKG to rule out heart rhythm disturbances through the night.

The polysomnogram is usually scored by a trained technician and then interpreted by a physician after the study data has been compiled. It is very important that all patients who have undergone a polysomnogram review the results with a physician and discuss treatment options directed at any disturbance that may have been noted on the test.

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