The arterial blood gas (often abbreviated as ABG) is a test to see how well a patient's lungs and heart are working to provide their body with oxygen and eliminating carbon dioxide. It also tells the doctor how stable is a patient's blood's acid-base balance. It can also be useful to identify any unwanted gases in a patient's blood, such as carbon monoxide. The arterial blood gas test is an important test used in every major hospital in America.
The test is done by inserting a needle into an artery usually in the patient's arm. The blood drawing is often done by either a respiratory therapist, nurse or doctor. It is important to obtain only the arterial blood without any venous blood mixing as this will distort the results. Patients who usually need this type of test are those who suffer from asthma, COPD (Chronic Obstructive Pulmonary Disease), pneumonia, anemia, heart attack and any other breathing or heart problems.
The test is also used for people who may have been exposed to environmental gases such as carbon monoxide or smoke inhalation from a fire. Therefore, people with smoke inhalation such as burn victims would also have this test performed.
Any patient receiving mechanical ventilation would also have regular ABGs drawn in order to monitor how well they're being ventilated. Ideally, the oxygenation range is maintained between 100-80% with a corresponding pO2 (partial pressure of oxygen) of 60-100 mmHg (millimeters of mercury, which is a pressure measurement). The ideal carbon dioxide reading is a pCO2 (partial pressure of carbon dioxide) of 35-45 mmHg with a normal pH of between 7.35 to 7.45, which is a measure of the acid-base status of the blood. These values may vary slightly depending upon the individual hospital's laboratory performing the test.
The test can also be done on babies who are premature or who are in the neonatal unit. In order to draw the arterial blood from the babies it is important to not draw too much blood. Therefore, a capillary heal stick is usually done so that not too much blood is needed to analyze the ABGs.
The arterial blood gas test is vitally important in order to guide the doctor and other health care providers in determining the appropriate therapy for their patients and for monitoring the effects of the therapies that they give their patients. For these reasons it is widely used throughout the health care system today.