**Question:** In a patient with a pO2 of 85 mmHg, pCO2 of 50 mmHg, pH of 7.2, and HCO3- of 36mmol/L. The condition is:

A. Respiratory Acidosis
B. Metabolic Acidosis
C. Respiratory Alkalosis
D. Metabolic Alkalosis

**Core Concept:** The acid-base balance in the body is maintained by the balance between respiratory and renal buffering systems. Acid-base disturbances occur when the pH deviates from the normal range of 7.35-7.45.

**Why the Correct Answer is Right:** The patient's pH is 7.2 which indicates a significant acidemia. The alkalinity (base excess) is -8.9, suggesting a severe acidosis. The pO2 is elevated, suggesting respiratory insufficiency, which contributes to the respiratory acidosis. The pCO2 is elevated, confirming the respiratory acidosis. An elevated HCO3- (36 mmol/L) indicates a compensatory mechanism to counteract the acidosis.

**Why Each Wrong Option is Incorrect:**

A. Respiratory Acidosis (pH 7.2, pCO2 50 mmHg, and HCO3- 14 mmol/L) is not the correct answer because the pO2 is normal (85 mmHg), not elevated as in this scenario.

B. Metabolic Acidosis (pH 7.2, pCO2 50 mmHg, and HCO3- 14 mmol/L) is incorrect due to the elevated pO2 (85 mmHg) and normal HCO3- level (14 mmol/L), indicating a respiratory acidosis rather than a renal or hepatic cause for acidosis.

C. Respiratory Alkalosis (pH 7.2, pCO2 50 mmHg, and HCO3- 14 mmol/L) is not the correct answer. The elevated pO2 (85 mmHg) suggests respiratory insufficiency, not alkalosis. Additionally, the normal HCO3- level (14 mmol/L) contradicts the expected decrease in HCO3- seen in alkalosis.

D. Metabolic Alkalosis (pH 7.2, pCO2 50 mmHg, and HCO3- 14 mmol/L) is incorrect due to the elevated pCO2 (50 mmHg), indicating respiratory alkalosis. However, the patient has a normal pO2 (85 mmHg) and decreased HCO3- (14 mmol/L), suggesting a renal or hepatic cause for alkalosis instead of respiratory alkalosis.

**Clinical Pearl:** A pH of 7.2 is considered normal in adults, but in neonates, it is considered acidotic (below 7.2) due to their immature lungs and higher respiratory rate.

**Correct Answer:** Respiratory Acidosis (pH 7.2, pCO2 50 mmHg, and H