What is blood pressure?
Blood pressure is the force that the circulating blood
exerts on the walls of the arteries.
Why is blood pressure measured?
It helps the ICU staff monitor the heart and blood flow in
the body.
What is a normal blood pressure
reading?
Blood pressure varies with age, sex, size and condition of
the individual. Normal blood pressure levels vary but a
normal reading is approximately 120/60, referred to as "120
over 60". The first or top number is the systolic pressure.
This is the pressure generated during contraction of the
heart. The second or bottom number is the diastolic
pressure. This is the pressure in the arteries when the
heart is in the relaxation phase. A critically ill or
injured patient's blood pressure may vary greatly, depending
upon the patient's condition and current course of therapy.
High blood pressure (hypertension) is consistently elevated
blood pressure exceeding 140 over 90. Systolic pressure is
considered abnormally elevated if consistently over 150.
Diastolic pressure is considered abnormally elevated if
consistently over 90.
What happens when the blood
pressure level is too low or too high?
Depending upon the patient, extreme changes in the level of
blood pressure may be harmful. If the level is low, the
patient's body and organs may not receive enough blood flow
and oxygen. If a low level of blood pressure cannot be
corrected, the patient's body functions and organs including
the brain, heart, kidneys, and liver, may be at risk to
fail. If the level is high, the patient's body and organs
may be exposed to high pressures that cause damage leading,
if uncorrected, to organ failure.
How is blood pressure measured?
The blood pressure device, a sphygmomanometer, is one of the
most commonly used instruments in the ICU. It consists of an
inflatable cuff attached to two small tubes that run to the
readout or display portion of the device. The cuff is
wrapped around the patient's upper arm. The cuff is
inflated, then gradually deflates. It senses blood flow and
pressure while the heart muscle is both contracting and
relaxing. This information is transferred via the tubing to
the readout portion of the device.
Does use of a blood pressure device
hurt?
No, but the patient can feel the device inflating and
deflating.
Can blood pressure be measured
another way?
Yes, when the blood pressure is lower or higher than
desired, many physicians choose to use a more accurate
method of measuring blood pressure, called an intra-arterial
blood pressure monitor. In this case, a small tube
(catheter) is inserted directly into an artery, usually in
the wrist, groin, armpit, or foot. The catheter is connected
to the monitor. Blood pressure is continuously displayed on
the monitor.
How long is an intra-arterial blood
pressure monitor used?
The intra-arterial blood pressure monitor is normally used
only for a short time.
Does intra-arterial blood pressure
monitoring hurt?
Yes, when the catheter is first inserted the patient
experiences discomfort similar to that felt when blood is
drawn for testing. However, the discomfort soon goes away.
Are there any potential
complications associated with blood pressure measurement or
monitoring?
There are no significant complications associated with
monitoring blood pressure by the inflatable cuff method.
Bleeding and infections are rare complications associated
with intra-arterial blood pressure monitoring.
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A common type of blood pressure device |
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Arterial blood pressure (ABP - 103/67)
displayed on a bedside monitor |
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Blood Pressure Measurement 
