Quiz on Acid-Base Balance Assessment

A patient is admitted with severe diarrhea and the following lab values: pH 7.25, PaCO2 40 mmHg, HCO3- 15 mEq/L. Evaluate the acid-base disturbance and its likely cause.

• Metabolic acidosis due to loss of bicarbonate

• Respiratory acidosis due to CO2 retention

• Metabolic alkalosis due to loss of hydrogen ions

• Respiratory alkalosis due to increased ventilation

Answer explanation

The lab values indicate a low pH and low HCO3-, consistent with metabolic acidosis. The severe diarrhea likely caused a loss of bicarbonate, leading to this acid-base disturbance.

A patient with COPD has the following lab values: pH 7.36, PaCO2 55 mmHg, HCO3- 30 mEq/L. Evaluate the acid-base status and determine if compensation is occurring.

• Uncompensated respiratory acidosis

• Compensated respiratory acidosis

• Uncompensated metabolic acidosis

• Compensated metabolic alkalosis

Answer explanation

The pH of 7.36 indicates acidosis, with a high PaCO2 of 55 mmHg confirming respiratory acidosis. The HCO3- of 30 mEq/L shows metabolic compensation, making it compensated respiratory acidosis.

A patient with a history of chronic kidney disease presents with the following lab values: pH 7.28, PaCO2 36 mmHg, HCO3- 18 mEq/L. Evaluate the most likely cause of the acid-base imbalance.

• Respiratory acidosis due to hypoventilation

• Metabolic acidosis due to renal failure

• Metabolic alkalosis due to vomiting

• Respiratory alkalosis due to hyperventilation

Answer explanation

The lab values indicate a low pH and low HCO3-, consistent with metabolic acidosis. In chronic kidney disease, the kidneys cannot adequately excrete acids, leading to this acid-base imbalance.

A patient with a history of vomiting presents with the following lab values: pH 7.48, PaCO2 44 mmHg, HCO3- 30 mEq/L. Evaluate the acid-base disturbance and its likely cause.

• Metabolic acidosis due to diarrhea

• Respiratory acidosis due to hypoventilation

• Metabolic alkalosis due to loss of gastric acid

• Respiratory alkalosis due to hyperventilation

Answer explanation

The lab values indicate a pH of 7.48 (alkalosis) with elevated HCO3- (30 mEq/L), suggesting metabolic alkalosis. This is likely due to loss of gastric acid from vomiting, which decreases hydrogen ions and raises pH.

A patient presents with the following lab values: pH 7.32, PaCO2 50 mmHg, HCO3- 24 mEq/L. Based on these values, evaluate the patient's acid-base status.

• Metabolic acidosis

• Respiratory acidosis

• Metabolic alkalosis

• Respiratory alkalosis

Answer explanation

The pH of 7.32 indicates acidosis. The elevated PaCO2 of 50 mmHg suggests respiratory failure, leading to respiratory acidosis. HCO3- is normal, confirming that the primary issue is respiratory, not metabolic.