Hemodynamic Monitoring

What is hemodynamic monitoring?

Hemodynamic monitoring directly measures blood pressure from inside the veins, heart, and arteries. It also measures blood flow and how much oxygen is in the blood. It is a way to see how well your heart is working.

When is it done?

Many treatments depend on seeing small changes in the way the heart is working. Changes in blood pressure and blood flow first occur deep inside the body. It may take time for these changes to show at the body surface, where they can be more easily measured. Hemodynamic monitoring can detect these changes by testing samples of blood from deep inside the body.

Hemodynamic monitoring helps predict if you will need blood or fluid transfusions. It shows whether the lungs are getting enough oxygen. It checks how well the heart is pumping by measuring the total flow of blood per minute. It may be used, for example, if you are in intensive care recovering from a heart attack or if you have fluid around the heart (cardiac tamponade).

What happens during the test?

Your arterial blood pressure is monitored by inserting a short, thin tube (cannula) through your skin and into one of your arteries, usually a wrist artery. Before the tube is inserted, you will be given a shot to numb the area.

The outside end of the tube is attached to a device called a transducer. The transducer changes the blood pressure measurement into an electrical signal that is displayed on a TV monitor. Changes in blood pressure can then be easily seen at a glance. The cannula also makes it easy to get blood samples to measure the oxygen level in the blood.

Checking the blood circulation in the artery that brings blood to the lungs (the pulmonary artery) is slightly more complex. Your healthcare provider will insert a long tube called a catheter into a vein. The veins most commonly used are in the neck, under the collarbone, or in the leg. You will be given a shot to numb the area where the tube is inserted. The catheter is often called a right heart catheter, a pulmonary artery catheter, or a Swan-Ganz catheter.

The outside end of the long catheter is attached to a transducer for pressure measurements. The other end of the catheter has a small balloon at its tip. Inflating the balloon with a small amount of air helps the catheter float through the heart into the artery to the lungs. When the catheter is in the right position, the balloon is deflated and the catheter left in place. The catheter does not cause any pain.

The catheter allows your healthcare provider to measure the blood pressure in your pulmonary artery. The amount of blood pumped by the heart and the amount of oxygen in the blood are also measured. This shows how well the heart's left ventricle, its main pumping chamber, is working. Even slight changes in your blood flow and the pumping ability of your heart can be detected with these measurements.

What are the benefits of this test?

This test can find problems with how the heart is working. Correcting problems early may prevent complications. This is very important for some people who need to have surgery or who are very ill.

What are the risks of this test?

There is a risk of infection. Although the tubes are sterile when they are put into your body, the chance for infection increases the longer they are in your body. Most hemodynamic monitoring lasts for only a few days. Bleeding can also be a problem, but severe bleeding problems are rare.

Rarely, a lung may collapse when the tube is inserted into the heart. It is usually easy to know when a lung has collapsed, and the lung can be quickly reinflated. Abnormal heart rhythms may also occur.

Written by Donald L. Warkentin, MD.
Published by RelayHealth.
© 2009 RelayHealth and/or its affiliates. All Rights Reserved.