What does a small margin between systolic & diastolic blood pressure mean?

Blood pressure is the force of blood moving through the arteries in your body. When a person’s blood pressure is taken, it is measured by two numbers--the systolic pressure and the diastolic pressure. The systolic number is when the blood pressure is at its highest as the heart beats. The diastolic number means the heart is at rest. The difference between the two numbers is called pulse pressure.

A narrow pulse pressure is usually indicative of shock caused by some kind of trauma, though there can be a number of causes.

There are several things that can cause low or narrow pulse pressure, including shock, low stroke volume (low total blood volume) or low cardiac output. Some causes of shock include a heart attack, sudden blood loss due to an injury or a significant loss of body fluids.

Additional causes include aortic stenosis (the incomplete opening of the aortic valve), anaphylaxis (allergic reaction), cardiac tamponade (the collection of blood or fluid in the space between the heart muscle and the membrane covering the heart) and heart failure.

A normal pulse pressure shouldn’t be more than 60. For example, a normal blood pressure is 120/80, which equates to a pulse pressure of 40. This is OK. However, just because a person's pulse pressure is 40, doesn't indicate anything. A person's blood pressure can be 140/100 with the pulse pressure being 40. This is completely different. The pulse pressure alone shouldn't be the only determining factor in a person's medical condition. A complete physical exam is required to determine what may be wrong with the patient.

Many doctors will place patients on blood pressure medication to stabilise the person’s blood pressure. When that isn’t enough, as in the cases for severe shock or a heart attach, sometimes hospitalisation is required.