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| Ear, Nose and Throat (ENT) | Used to refer to a physician that specializes in disorders of that region; Technically known as an Otorhinolaryngologist |
| Edema | A local or generalized condition due to the build-up of excessive amounts of extra-cellular fluid and characterized by swelling |
| Electro-encephalogram (EEG) | A recording of the electrical activity of the brain by means of electrodes placed on the surface of the head |
| Electro-oculogram (EOG) | A recording of the electrical activity of the eyes; Used to verify sleep changes including REM |
| Electromyogram (EMG) | A recording of electrical activity from the muscular system/muscle activity; Used to assist in the scoring of sleep stages such as REM; Also used to measure muscle activity to help diagnose PLMS |
| Epoch | A measure of duration of the sleep recording typically 20-30 seconds; An epoch corresponds to one page of the polysomnogram |
| Exacerbation | A worsening of a condition, usually acutely |
| Excessive Daytime Sleepiness or Somnolence (EDS) | 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 |
| Expiratory Phase (Exhalation) | The part of the ventilatory cycle from the beginning of expiratory flow to the beginning of inspiratory flow |
| Expiratory Positive Airway Pressure (EPAP) | The lower pressure used in BiPAP; Helps maintain airway patency and oxygenation |
| Extubation | The removal of a tube that has been inserted into the airway |