Electronystagmography is an accepted, reliable, and accurate method for determining the status of a patient's vestibular functions. The test is based on recording eye movements based on the cornea-retinal potentials. The printed record of the nystagmus makes it available for comparison with subsequent tracings. It is a better technique for diagnosing true vertigo or labyrinthine disease.

BAER is a technique of evoking production of electrical responses when stimulated by controlled sound. It is an improved technique because it is a valuable tool for assessing hearing when the test subject is incapable or unwilling to respond to auditory testing. The test is particularly useful in testing infants or young children.

The parameters of interest that are usually monitored during sleep are as follows:

1. 1. 

   REM: Electro-oculogram of rapid eye movement to determine depth or stage of sleep.

2. 2. 

   Respirations: rate, tidal volumes, chest excursion.

3. 3. 

   ECG monitoring mainly for rate and arrhythmia.

4. 4. 

   Blood pressure (BP).

In particular cases, more comprehensive evaluations include:

1. a. 

   Electroencephalogram (EEG).

2. b. 

   Esophageal pressure.

3. c. 

   Audiovisual taping.

4. d. 

   Electromyogram (EMG).

5. e. 

   Arterial blood gas analysis.

6. f. 

   Oral and nasal respiration.

7. g. 

   Chest and abdominal excursion.

The finding of obstructive sleep apnea under this comprehensive monitoring provides an improved diagnostic technique for evaluation of impairments of the cardiopulmonary system.