I've had two tilt table tests as I have bad blood pressure problems and faints due to POTS (Postural Orthostatic Tacharcadia Syndrome).

For me, they laid me down flat on a bed for around 15 minutes and monitored my blood pressure every few minutes. They then tipped the bed up to a 60 degrees tilt and monitored my blood pressure and pulse. You have a blood pressure cuff on one arm and something to record your pulse on one of your fingers. It squeezes all the time and can lead to a numb finger temporarily, just to warn you. You are hooked up to machines all the time and they constantly monitor your BP / pulse and also temperature.

The second tilt table I had a few weeks ago also involved a cannula. They took bloods 10 minutes into the test and then again another 10 minutes later. They explained this was to see if my body was 'leaking' adrenalin.

For me, the tests weren't nice because the tilt increased my usual symptoms o faints, headaches, nausea etc. They do however stop them if they see you are unwell (I was in hypertensive crisis on mine so they stopped it). Its different for everyone though.

Let us know how you get on and I hope the test helps you get a diagnosis.