Tilt table test
A tilt table test is used to diagnose if postural orthostatic tachycardia syndrome, also called POTS, or neurally mediated hypotension, also called NMH, is the cause of your dysautonomia, light-headedness, or syncope. Vital signs, especially heart rate and blood pressure are monitored as the table slowly raises the patient from lying to nearly standing position. The patient is strapped to the table in case the patient faints in the upright position. Other conditions that can be diagnosed with a tilt table test is cardiac arrhythmia.
The Full Report "Beyond Myalgic Encephalomylitis/Chronic Fatigue Syndrome: Redefining an Illness" (2015) pgs. 111-119 covers Tilt Table Test: "Assessment of Orthostatic Intolerance and Autonomic Dysfunction in ME/CFS"