A patient with salicylic acid poisoning has the following arterial blood gas analysis report: pH is 7.12 , PCO2 is 18 mm Hg HCO3– is 12 mmol/L. The resulting acid-base abnormality can be best labelled
**Core Concept**
The question tests the understanding of acid-base balance, specifically the effects of salicylic acid poisoning on arterial blood gas (ABG) analysis. **Salicylic acid** is a weak acid that can cause a mixed acid-base disorder.
**Why the Correct Answer is Right**
Given the patient's ABG report, the **pH is 7.12**, indicating acidosis. The **PCO2 is 18 mm Hg**, which is low, suggesting a respiratory alkalosis. The **HCO3– is 12 mmol/L**, which is low, indicating a metabolic acidosis. This combination of low PCO2 and low HCO3– with acidosis points towards a **mixed acid-base disorder**, specifically a **mixed respiratory alkalosis and metabolic acidosis**.
**Why Each Wrong Option is Incorrect**
**Option A:** This option would be incorrect if it suggested only a metabolic acidosis, as it doesn't account for the low PCO2.
**Option B:** Similarly, this would be incorrect if it only suggested a respiratory alkalosis, not considering the metabolic component.
**Option C:** If this option suggested another type of disorder, it would be incorrect based on the provided ABG values.
**Clinical Pearl / High-Yield Fact**
In salicylic acid poisoning, early recognition of mixed acid-base disturbances is crucial. The initial phase may present with respiratory alkalosis due to central hyperventilation, followed by or combined with metabolic acidosis due to the accumulation of organic acids.
**Correct Answer:** D. Mixed respiratory alkalosis and metabolic acidosis.