The amount of pressure within the arteries is measured as "Blood Pressure". It is often referred to as the "BP". It can be measured in your doctors office with a specially designed blood pressure cuff (Image 1). In critically ill patients, blood pressure is often measured continuously by an Arterial Line.

Blood pressure has a high, low and average pressure reading. An example of a common blood pressure reading is 120/80 with a "mean" or average pressure of 70. The top number is the pressure during "systole", or the period of time when the heart is pumping blood into the artery. The low number is the pressure in the artery when the heart is at rest (diastole). The mean pressure is the average pressure during the entire period of pumping and relaxing.

A low blood pressure reduces the ability to push enough blood into the capillaries. This can lead to low oxygen levels in the tissues or Ischemia. If the blood pressure is too high, the heart will have to work harder to pump against the high pressure.

Critically ill patients often require medications to make the blood pressure higher or lower. Drugs that change the blood pressure are called Vasoactive agents.


Image 1: Blood pressure taken by cuff.




Last Reviewed: October 23, 2014