Registered Nurses' Association of Ontario

Definition of Terms

Blood  pressure: Blood  pressure is the  product of the  amount of blood pumped by the  heart each minute (cardiac output) and the  degree of dilation or constriction of the  arterioles (systemic vascular resistance). It is a complex variable involving mechanisms that influence cardiac output, systemic vascular resistance, and blood volume. Hypertension is caused by one or several abnormalities in the function of these mechanisms or the  failure of other factors to compensate for these malfunctioning mechanisms.

Systolic Pressure: Systolic pressure represents the pressure when the heart contracts and forces blood into the blood vessels. This is the higher of the two numbers and is usually expressed first.

Diastolic Pressure: Diastolic pressure represents the  pressure when the  heart is relaxed. This is the lower of the  two numbers and is usually expressed second.

Hypertension: A medical condition in which blood pressure is consistently above the normal range.

To view Classifications of Hypertension (WHO/ISH) click here.


Another classification taxonomy described in  the   literature is  presented by  the   National Institutes of Health (2003):

Optimal <120 <80
Pre-hypertensive 120-139 80-89
Hypertensive >140 >90
Stage  1 140-159 90-99
Stage  2 >160 >100




Chronic Disease
Nursing Management of Hypertension
Background Information