( Beth Wegerbauer Contributing Editor...)Blood Gas Analysis: The Pros and Cons of Point-Of-Care Testing,Health

Beth Wegerbauer
Contributing Editor

Since the first system was invented in 1957, blood gas analysis has revolutionized clinical medicine and patient care. During the 1960s, blood gas analysis became almost universally available, and blood gases were considered "the most important laboratory test for critically ill patients," according to a www.bloodgas.org article by Dr. John Severinghaus, inventor of the blood gas analysis system.

Blood gas tests determine whether a patient has enough oxygen in his blood and whether or not that blood is pH balanced. The tests reveal levels of pH (indicating blood's acid/base status), pO₂ (how much oxygen is dissolved in blood), PCO₂ (how much carbon dioxide gas is dissolved in blood), as well as other parameters like O₂ saturation and HCO₃. Blood samples are collected from an artery, usually the radial artery in the wrist, but also can be taken from the brachial or femoral arteries. For infants, capillary blood may be taken from a heelstick. In addition to arterial sampling, blood gas panels can be ordered on blood drawn through a central venous line to estimate cardiac output.

Blood gas analysis is performed by trained health-care providers in a hospital, emergency room, or large clinical laboratory. These tests are "stat" tests, meaning they should be done as quickly as possible after sample collection. For arterial blood gases (ABGs), the collected sample degrades quickly and, if any testing delay is expected, it should be kept on ice and rewarmed later for accurate analysis. If, after sample collection, any air bubbles remain in the top of the syringe, they must be removed. After the needle is capped, the syringe is then placed on ice and transported for immediate analysis.

To reduce transport as well as turnaround time, especially for the most seriously ill patients, many analyzers are located in or near
'"/>