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Which acid-base imbalance is indicated by the following ABG: pH = 7.31, CO2 = 43, HCO3 = 19?

  1. Respiratory acidosis

  2. Metabolic acidosis

  3. Respiratory alkalosis

  4. Metabolic alkalosis

The correct answer is: Metabolic acidosis

The combination of the given arterial blood gas (ABG) values indicates metabolic acidosis. In this particular scenario, the pH is 7.31, which is below the normal range (7.35–7.45), suggesting an acidosis condition. In addition to the low pH, the bicarbonate (HCO3) level is 19, which is also below the normal range (22–26 mEq/L). This indicates a primary metabolic problem because the bicarbonate, which is a buffer in the blood, is low, and the body is likely experiencing an accumulation of acids or a significant loss of bicarbonate. The carbon dioxide (CO2) level of 43 is within the normal range and does not indicate significant respiratory compensation. In metabolic acidosis, the kidneys fail to excrete sufficient acid or produce enough bicarbonate, leading to a decreased HCO3 level and subsequently a decreased pH. This aligns well with the values provided, confirming that metabolic acidosis is indeed present. The lack of significant respiratory compensation (as indicated by the CO2 level) suggests that the acidosis is primarily metabolic in nature rather than respiratory.