An ABG analysis shows:pH 7.2, raised pCO2, decreased HCO3: Diagnosis is :

Okay, let's tackle this ABG question. The patient has a pH of 7.2, which is definitely acidic. The question is about mixed acid-base disorders. The pCO2 is raised, so that points towards respiratory acidosis because CO2 is a respiratory component. Then, HCO3 is decreased, which suggests metabolic acidosis. So the combination of respiratory acidosis and metabolic acidosis would explain the low pH with elevated CO2 and low bicarbonate.

Wait, but ABG interpretation can be tricky. Let me break it down. A low pH is acidosis. If pCO2 is high, that's respiratory acidosis. But if HCO3 is low, that's metabolic acidosis. So when both are present, it's a mixed disorder. The options probably include respiratory acidosis with metabolic acidosis. The other options might be other combinations like metabolic acidosis with respiratory alkalosis, etc. The user didn't provide the options, but based on the correct answer given, I need to explain why the correct answer is the combination of both acidosis types. The incorrect options would be other mixed disorders or pure acidosis. The clinical pearl here is that when pH is abnormal, check both pCO2 and HCO3 to determine if it's a single or mixed disorder. Also, remember that in pure respiratory acidosis, HCO3 would be elevated as a compensatory mechanism, not decreased. So if HCO3 is low, it's a mixed disorder. The correct answer is the combination of respiratory and metabolic acidosis. I need to make sure the explanation is clear and covers all the key points.

**Core Concept**
This question tests the interpretation of arterial blood gas (ABG) findings to diagnose mixed acid-base disorders. A low pH (<7.35) indicates acidosis; elevated pCO₂ suggests respiratory acidosis, while decreased HCO₃⁻ indicates metabolic acidosis. Mixed disorders occur when two primary processes coexist. **Why the Correct Answer is Right** The ABG shows **acidemia (pH 7.2)** with **elevated pCO₂** (respiratory acidosis) and **reduced HCO₃⁻** (metabolic acidosis). In pure respiratory acidosis, HCO₃⁻ rises due to renal compensation. Conversely, in pure metabolic acidosis, pCO₂ falls due to respiratory compensation. The **simultaneous presence of elevated pCO₂ and decreased HCO₃⁻** confirms a **combined respiratory and metabolic acidosis**. Common causes include severe sepsis, diabetic ketoacidosis with respiratory failure, or drug overdose (e.g., salicylate toxicity). **Why Each Wrong Option is Incorrect** **Option A:** Respiratory acidosis alone would have elevated pCO₂ and **normal or elevated** HCO₃⁻ (compensatory), not decreased. **Option B:** Metabolic acidosis alone would have **low pCO₂** (compensatory hyperventilation) and low HCO₃⁻, not elevated pCO₂. **Option C:** Respiratory alkalosis would present with **low pCO₂** and normal or low HCO₃⁻, conflicting with the given ABG. **Clinical Pearl / High-Yield Fact** Remember the **"delta-delta" rule**: In mixed disorders

✓ Correct Answer: C. Respiratory and metabolic acidosis