How to Perform a Arterial Blood Gas Analysis

Arterial blood gas analysis or ABGA is a test performed by clinicians in patients whom are having respiratory problems which need close observation. The analysis will indicate the concentration (partial pressure) of oxygen, carbon dioxide, bicarbonate in the blood, the pH level of the same as well as a profile of several other elements which is altered in respiratory or metabolic related conditions.

The test is performed most likely in in-patients especially in the ones who are admitted to intensive care units. But, it is possible to perform the procedure in patients who are in the normal ward setup as well. It does not need the patient to be anesthetized although a trained person, most likely to be a doctor, a nurse or a technologist should take the blood.

There are several steps one should follow in order to obtain the arterial blood sample and it is vital that the result are interpreted along with the clinical findings of the patients as well as in the context of current management of the said patient. Thus, let us see some of the steps that need to be carried out in performing this task.

Explaining the procedure to the patient:

This is vital as the patient or even the relatives will be worried when these tests are done. Explaining that it is useful to monitor and assess the respiratory function and the effectiveness of the management would most likely to be enough in gaining cooperation when performing the test.

Selecting the site:

The arterial blood can be obtained from several sites and the commonest would be the radial artery in the wrist. Apart from the radial artery, the brachial artery and the femoral artery can also be used for this purpose. Following selecting the site, the skin surface needs to be cleaned with an antiseptic solution and care should be taken to avoid possible contaminations at all times.

Performing the blood extraction:

Before the procedure an ice bag or a container with ice should be nearby as the syringe in which the arterial blood is extracted needs to be transported in such an environment in order to prevent further metabolic processes in the blood.

A syringe attached to a needle should be used in order to extract the blood and once the needle is in the artery the blood will flow into the syringe without the need to pull the plunger backwards. After enough blood is acquired, about 3 – 5 milliliters, the needle should be withdrawn and clean gauze should be used to apply direct pressure over the puncture site.

While the direct pressure is applied over the puncture site, the syringe should be handed over to another person to remove its needle and close with the cap and to take it to the lab as soon as possible using the ice filled container. This may not be needed in case the facilities are close by and the time delay is negligible.

The direct pressure should be sustained for about 5 minutes and a clean dressing should be applied over the puncture site with some pressure.

Following the procedure, the site needs to be kept under observation for appearance of swelling, pain…etc and the patient should be instructed to inform such changes as soon as possible.