Why blood pressure changes with sudden change of position?

Question

What type changes in both SBP and DBP takes place with sudden change of position from sitting to standing or from lying to standing? Why such changes takes place? Please provide scientific reasoning?

Answer 1

Changes in blood pressure according to changes in position is called postural hypotension or orthostatic hypotension. Simple scientific explanation is that during lying down or sitting, there is a normal but slowed down circulation of blood in the blood vessels. When you suddenly change your position by standing or getting up, there is sudden flow of blood and the blood pools in the blood vessels of the legs. Because of this pooling, the amount of blood carried back to the heart by the veins is decreased. Subsequently, less blood is pumped out from the heart, thus less blood is supplied to the body resulting in a sudden drop in blood pressure. That way you will feel dizzy or lightheaded which is a sign of having postural hypotension. That is why when you are in a prolonged sitting or lying position, you should change your position to standing gradually; that is sit straight for a while,dangling the legs before getting up. ♥

Answer 2

There is a certain amount of pressure associated with a column of fluid called HYDROSTATIC pressure.

The pressure at the bottom of the column is greater than that at the top.

The human body is somewhat like that when considering the pressure in the blood vessels (particularly the arteries, which is what we measure usually).

If the body is supine, then the blood pressure difference between the head and the feet is negligible. The arm, being at the same height also has the same hydrostatic pressure and hence a similar blood pressure.

When the body changes posture to a standing position, then there is a gravitational action upon the column of blood and there tends to be a greater pressure in the legs than in the head.

The arm is closer to the head and the blood pressure is a little lower in the arm once an upright pressure is achieved.

If this drop in blood pressure is significant/severe it is called "orthostatic hypotension" or "postural hypotension"

This effect is further enhanced by the fact that the veins of the body are somewhat distensible. The blood being drawn downwards by gravity can "pool" in the legs - particularly when the legs are still and there is no activity of the "muscle pump" to pump venous blood back to the heart. This decreases the amount of venous return and hence decreases the cardiac output, further lowering blood pressure.

If the blood pressure to the brain becomes insufficient to perfuse the neural tissue, lightheadedness and eventually collapse can ensue.

See the wiki page

Answer 3

120/80 is considered "textbook perfect" blood pressure, but there are a lot of factors that influence it. Some people just have lower blood pressures than others. Personally, I tend to run around with a BP of 106/60. I've been up and walking (although I was sick at the time) with a BP of 80/40. Having a low low BP is much better than having high blood pressure. As long as you are not light headed, it is nothing to worry about. Just let any doctor or paramedic that is treating you know that your BP normally runs this low. In your case, a BP of 120/80 could be something they might want to keep an eye on, depending on your other symptoms.

Answer 4

3 years ago, I was diagnosed - hypertension with a reading of 160/100. I used to feel dizzy a lot, my legs had awful cramps, and levels were very low in my potassium, causing my fingers and toes to always cramp together. One day I started to feel really faint while I was driving with my daughter in the back seat and I passed out, hitting 3 cars and ending up in a ditch. That moment,I knew I had to do something because my meds weren't working. I heard about this diet from a friend and thought I'd give it a shot. The results have been remarkable. In just 21 days, I honestly can't remember feeling this good, my blood pressure went from 175/110 to 125/70.