Blood pressure

[Sten]

Note: I have read the sticky and I understand what was stated there.

I have a question about shock and blood pressure. I know that when I am under high stress my blood pressure spikes way up. I have wondered for years if these is any positive physiological reason why a persons blood pressure would spike.

A hypotheses that I have is that "fear/stress/fight flight reaction " triggers the BP spike to combat the potential for shock?

Is a loss of BP a major contributing factor to shock?

[18C/GS 0602]

The term shock is commonly used to mean many different things. Medically it is a state where the circulatory system (heart and blood vessels) fails to provide enough blood and oxygen to your vital organs. There are different causes of shock such as blood loss, heart failure, or dilation of blood vessels. They all result clinically in low BP.

When you are under stress (fight or flight) your body releases catecholamines (commonly known as adrenaline) that do many of different things including increasing your heart rate and blood pressure. Having a release of catecholamines may or may not be a good thing depending on what is causing the shock. If you are shot and have lost a lot of blood it is a good thing because it helps increase oxygen delivery to your vital organs. However if you are in heart failure and your blood pressure is up because of a stressor that just makes it more difficult for the heart to pump and results in less perfusion. Clear as mud?

[Sten]

so higher BPs can actually decrease blood flow?

[18C/GS 0602]

In order to answer your question I have to give you a little background. Your heart and blood vessels can be though of a plumping system. In order to have blood flow you have to have a pressure gradient. Your BP is expressed as two numbers; the systolic pressure, which is the pressure in your arteries when the heart is contracting, and the diastolic pressure, which is the pressure in the arteries when the heart is relaxed. When the heart begins to contract it has to create a pressure that is higher than your diastolic pressure in order to create a pressure gradient; this results in blood flow. When your body releases a bunch of catecholamines this causes an increase in both your diastolic and systolic BP. If your heart is failing and not pumping well and you increase your diastolic pressure it results in less of a pressure gradient and thus less blood flow. This results in less perfusion and worsening shock. Sorry if I am not explaining this clearly.