In interpreting arterial blood gases, what should be done first to confirm metabolic acidosis?

To confirm metabolic acidosis in arterial blood gases (ABGs), the first step should be determining if the pH is acidotic. The pH provides direct insight into the body's acid-base status. In metabolic acidosis, the pH typically falls below the normal range (7.35-7.45), indicating acidosis.

Once the pH is established as acidotic, further evaluation can include looking at the bicarbonate (HCO3) levels, which will usually be low in metabolic acidosis as the body is attempting to compensate for the acidemia. However, analyzing the pH first gives the foundational understanding needed to guide the interpretation of the other values in the ABGs.

The other options, while important in the overall assessment, do not serve as the first confirmation for metabolic acidosis. Analyzing HCO3 can indicate if there is a primary metabolic process, but it presumes that one has already determined the pH status, which is not the most effective first step. Assessing O2 saturation is more relevant for respiratory issues and does not directly indicate acid-base status. Evaluating CO2 levels can show respiratory compensation or opposite pathology but is secondary to establishing the pH's status first. Thus, confirming that the