NCC Certified Electronic Fetal Monitoring (C-EFM) Practice Exam

What is indicated by a pH of 7.22, pCO2 of 50, HCO3 of 24, and BE of -3?

1. Respiratory alkalosis

2. Normal acid-base status

3. Metabolic alkalosis

4. Metabolic acidosis

The correct answer is: Normal acid-base status

To determine the acid-base status indicated by a pH of 7.22, pCO2 of 50, HCO3 of 24, and base excess (BE) of -3, one must analyze the values provided. A pH of 7.22 is considered low, indicating acidemia, since the normal pH range is generally between 7.35 and 7.45. The elevated pCO2 of 50 suggests a respiratory component because it indicates that carbon dioxide is being retained, leading to an increase in acidity through the formation of carbonic acid. A normal pCO2 is usually around 35 to 45 mmHg. The bicarbonate level at 24 falls within the normal range (22-28), showing that there is no significant metabolic compensation present. The base excess of -3 further confirms that there is a mild decrease in bicarbonate relative to normal levels, but this is not enough to classify the status as metabolic acidosis alone, given that the bicarbonate level remains within the normal range. In this situation, the primary disorder is respiratory acidosis due to the elevated pCO2 leading to the decreased pH. The lack of significant metabolic compensation (normal HCO3) and