Sampling and Analysis
Arterial blood for blood gas analysis is usually drawn by a respiratory therapist and sometimes a phlebotomist, nurse or doctor. Blood is most commonly drawn from the radial artery because it is easily accessible, can be compressed to control bleeding, and has less risk for occlusion, the selection of which radial artery to draw from is based on the outcome of an Allen's test. The femoral artery (or less often, the brachial artery) is also used, especially during emergency situations or with children. Blood can also be taken from an arterial catheter already placed in one of these arteries.
The syringe is pre-packaged and contains a small amount of heparin, to prevent coagulation or needs to be heparinised, by drawing up a small amount of heparin and squirting it out again. Once the sample is obtained, care is taken to eliminate visible gas bubbles, as these bubbles can dissolve into the sample and cause inaccurate results. The sealed syringe is taken to a blood gas analyzer. If the sample cannot be analyzed within 10–15 minutes, it must be placed on ice for valid results. Even when placed on ice, samples should still be analyzed within 1 hour.
Standard blood tests can also be performed on arterial blood, such as measuring glucose, lactate, hemoglobins, dys-haemoglobins, bilirubin and electrolytes.
Read more about this topic: Arterial Blood Gas
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