Arterial Blood Gas

872 Words2 Pages

Arterial Blood Gas

Indications: An ABG is ordered as a way to assess or manage a

patient’s respiratory and metabolic acid/base balance. The test

assesses the pH of a patient’s blood and is used as an indicator for

the particular cause of the acidosis or alkalosis.

An ABG is also used to measure adequacy of treatment for an acid/base

balance.

An ABG can also be used in the measurement of adequacy of oxygenation.

Type of Test and testing procedure:

An ABG is usually acquired through withdrawal of arterial blood.

Babies can be tested using whole blood through capillary heel sticks.

An ABG is usually collected from the radial artery. Before an ABG can

be preformed, a circulation test must be preformed to protect the

hand’s collateral blood flow. This is called the Allen Test.

Allen Test- Apply pressure to the radial and ulnar arteries,

eliminating blood flow to the chosen hand. Slowly release the

pressure on the ulnar artery. If the hand flushes, returning blood to

the hand by the ulnar artery, the test may be preformed. If the hand

does not flush, it indicates that there is poor collateral circulation

and this hand may not be used. Attempt to use the other wrist, if

unable to use either, the femoral artery or brachial may also be used.

The test may be preformed following a positive Allen test. An ABG

syringe contains approximately 0.2ml of heparin to prevent coagulation

of sample. Insert syringe at a 45-75 degree angle. Do not pull back

on syringe; allow the arterial blood pressure to fill the syringe.

After withdrawing 3ml, remove syringe and apply pressure. Because the

vessel is an artery, pressure mu...

... middle of paper ...

...it unless they are symptomatic.

Carboxyhemoglobin

One consideration that must be made when drawing an ABG is

carboxyhemogloblin. Carboxyhemoglobin is the binding of carbon

monoxide (CO) with the hemoglobin molecules in the blood. This occurs

with carbon monoxide poisoning, fire, and long-term heavy smokers.

The hemoglobin molecules bond much easier to CO than O2, thus causing

the carboxyhemoglobin level to rise quickly.

An increased carboxyhemoglobin level can cause a decreased pH, but a

low PaCO2. Thus, if a practitioner suspects CO poisoning or fire a

carboxyhemoglobin level must be drawn.

Normal Level: 5%

Interpreting Results:>5% and symptomatic, such as confusion, dyspnea

and severe headache

Treatment: High flow O2 and removal of causative agent. O2 will

counteract the CO level quickly.

Open Document