Saunders Respiratory Practice 2026 - Free Respiratory Practice Questions and Study Guide

The laboratory finding consistent with metabolic acidosis is indicated by a low pH, typically below 7.35, and a decreased bicarbonate (HCO3-) level, generally less than 22 mEq/L. In this case, the provided values of a pH of 7.30 and an HCO3- of 18 mEq/L fit these criteria perfectly.

This combination reveals that the acidity in the blood is high, which is characteristic of metabolic acidosis. In metabolic acidosis, the primary disturbance is a decrease in the bicarbonate concentration, leading to a lower pH level. The Pco2, or partial pressure of carbon dioxide, remains relatively stable at 40 mm Hg in this example, suggesting that the respiratory system is compensating or that a primary metabolic issue is present.

In contrast, the other choices present values that do not align with metabolic acidosis. For instance, the first choice shows a high pH, indicating alkalosis rather than acidosis. The second choice shows values within a normal range, suggesting a compensated state. The third choice presents a slightly elevated pH and HCO3- level that again does not indicate acidosis. Thus, the selected values in option D clearly identify a