For arterial blood gas (ABG) analysis, an arterial blood sample is preferred because it provides accurate measurements of gas exchange and the acid-base status of the blood. This type of sample reflects the oxygen and carbon dioxide levels in the arterial blood, which directly correlates with the lung's ability to oxygenate blood and remove carbon dioxide.
Unlike venous blood, which is influenced by metabolic activity in the tissues and can reflect the overall oxygenation status of the body, the arterial blood sample specifically highlights the efficiency of pulmonary gas exchange. Capillary blood samples can provide useful information in certain contexts, especially for quick assessments in neonates, but they may not accurately represent arterial conditions due to potential contamination with venous and interstitial fluid.
Serum samples, on the other hand, involve the separation of blood cells from plasma after coagulation and are not suitable for analyzing respiratory gases, as the analysis requires whole blood to measure the partial pressures of gases directly. Therefore, the preference for arterial samples in ABG analysis is critical for obtaining reliable and clinically relevant results.