Purpose of the Tilt-Table Exam
To put it simply, the tilt-table test is used to confirm episodes of low blood pressure that can occur when the body moves from laying flat to standing upright. This phenomenon is known as orthostatic, vasovagal, or postural hypotension. (It's the sensation we sometimes feel when we arise quickly to a standing position.) When individuals suffer from severe dizziness, lightheadedness, or fainting spells; it's important to find the cause. After cardiac irregularities (like an irregular heart beat) and other acute health concerns have been ruled out, the tilt-table test is a simple way to investigate further.
Why does low blood pressure occur with a change in position?
The lightheadedness caused by a sudden move from "flat" to upright is the result of gravity causing blood to momentarily pool in the legs. Our nervous system usually compensates quickly by causing the vessels in the the legs to constrict (squeeze tightly), forcing the blood back into circulation. Sometimes this compensatory mechanism is impaired, and the brain is temporarily deprived of blood and oxygen causing symptoms that can include fainting. (Note: Dehydration can contribute to orthostatic hypotension, but more serious causes may need to be further ruled out.)
How the Tilt-Table Test is performed
In the doctor's office or emergency room, orthostatic hypotension is confirmed by simply measuring changes in the blood pressure and pulse in succession: laying flat, sitting upright, and standing. The tilt-table exam is different in that it allows continuous monitoring of the heart and vital signs. The patient is placed flat on the horizontal table. A foot rest at the end of the bed supports the patient as the table is electronically moved by degrees to a vertical or standing position. Significant changes in the vital signs during the exam, fainting, nausea, sweating or any other physical symptoms will help the physician determine a diagnosis.
For more information:
Robert Wood Johnson University Hospital's tilt-table procedural overview
I can't figure out how to embed this video into the blog, but it's well worth watching if you want to visualize the procedure: Video: What happens during the tilt-table test?