Medicine

A man is found comatose in his room, having taken an unknown number of sleeping pills. An aerial blood sample yields the following values: pH 7.10, HCO3 – 12 meq/liter, PaCO2 66 mm Hg. This patient’s acid – base status is most accurately described as:

Name: A man is found comatose in his room, having taken an unknown number of sleeping pills. An aerial blood sample yields the following values: pH 7.10, HCO3 – 12 meq/liter, PaCO2 66 mm Hg. This patient’s acid – base status is most accurately described as:
Published: 2024-04-13T17:08:40+05:30
Keywords: Medicine

💡 Explanation

## Core Concept
The patient's acid-base status can be determined by analyzing the arterial blood gas (ABG) values provided: pH, bicarbonate (HCO3-), and partial pressure of carbon dioxide (PaCO2). The acid-base disorders can be classified into respiratory and metabolic categories, with the possibility of mixed disorders.

## Why the Correct Answer is Right
To analyze the acid-base status:
- The pH is 7.10, which indicates acidosis.
- The HCO3- level is 12 meq/liter, which is low (normal range approximately 22-28 meq/liter), suggesting metabolic acidosis.
- The PaCO2 is 66 mm Hg, which is elevated (normal range approximately 35-45 mm Hg), indicating respiratory acidosis.

Given these values, the patient has both a low bicarbonate level (metabolic acidosis) and an elevated PaCO2 (respiratory acidosis), with a pH that confirms acidosis. The presence of both metabolic and respiratory components to the acidosis is best described as mixed acid-base disorder, specifically mixed metabolic and respiratory acidosis.

## Why Each Wrong Option is Incorrect
- **Option A:** This option would describe a different acid-base disorder, which does not match the provided lab values.
- **Option B:** This option might suggest a single type of acidosis or a different combination that does not fit the lab values provided.
- **Option C:** This could potentially describe a respiratory acidosis with some degree of metabolic compensation but does not accurately reflect the significant metabolic acidosis component.
- **Option D:** If this option does not describe mixed metabolic and respiratory acidosis, it would be incorrect based on the lab values provided.

## Clinical Pearl / High-Yield Fact
A key point to remember is that in mixed acid-base disorders, the pH can be normal or abnormal, depending on the balance between the different components. However, the presence of both a significant increase in PaCO2 and a decrease in HCO3- with an acidotic pH strongly suggests a mixed disorder. When calculating the anion gap (AG = Na+ - [Cl- + HCO3-]) can help in identifying the type of metabolic acidosis.

## Correct Answer: C. mixed metabolic and respiratory acidosis.

✓ Correct Answer: C. Mixed respiratory and metabolic acidosis

A man is found comatose in his room, having taken an unknown number of sleeping pills. An aerial blood sample yields the following values: pH 7.10, HCO3 – 12 meq/liter, PaCO2 66 mm Hg. This patient’s acid – base status is most accurately described as:

A man is found comatose in his room, having taken an unknown number of sleeping pills. An aerial blood sample yields the following values: pH 7.10, HCO3 – 12 meq/liter, PaCO2 66 mm Hg. This patient’s acid – base status is most accurately described as:

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