[update] Blood Pressure measurements with the Finometer device

As I said on my last post, the University of Melbourne was doing a study about blood pressure and how polymorphisms in a gene for a sodium channel affects it. We had another prac today, for the follow-up since some of us were allocated to take sodium tablets for two weeks (and everyone else did more measurements even without taking the tablets too).

I got the results from three weeks ago of the readings of a "Finometer" before and after taking GTN (glyceryl trinitrate, aka nitroglycerin; used for treatment in angina, which dilates blood vessels), and before, during and after standing up from lying down. The Finometer measured a lot of different things (and calculated others using algorithms) in real time; including blood pressure (systolic and diastolic), heart rate, stroke volume, cardiac output and total peripheral resistance.

I was somewhat surprised at how much the blood pressure dropped when I stood up. Without the GTN, straight after standing up, the lowest systolic measured for me was 54 mmHg and for diastolic it was 34 mmHg, even though I am relatively young so the reflexes should not be too bad. After taking GTN, straight after standing up, the lowest systolic measured was 37 mmHg and lowest diastolic was as low as 18 mmHg! I never expected that my blood pressure would ever be that low, but now I know.

The professor/demonstrator then told me that now I should be able to understand why a lot of old people faint when they take GTN and try to stand up. For some reason, I might have felt a little dizzy, but even when my blood pressure was as low as 37/18 I still didn't feel like I was about to faint. Strange. Maybe because it was only for a few seconds.