Aerial blood gas analysis of a patient admitted to the medical emergency is as follows: pH=7.2, HCO3=38 mmol/L, Pco2 = 56 mm Hg. This indicates
**Question:** Aerial blood gas analysis of a patient admitted to the medical emergency is as follows: pH=7.2, HCO3=38 mmol/L, Pco2 = 56 mm Hg. This indicates
A. Hypercapnia
B. Hypocapnia
C. Hyperventilation
D. Metabolic acidosis
**Core Concept:**
Blood gas analysis is a critical tool in assessing a patient's respiratory and acid-base status. The parameters typically evaluated include pH (acid-base balance), HCO3 (bicarbonate levels), and PCO2 (carbon dioxide partial pressure). A normal range for these parameters is:
- pH: 7.35-7.45
- HCO3: 22-28 mmol/L
- PCO2: 35-45 mmHg
**Why the Correct Answer is Right:**
The patient's blood gas analysis reveals the following:
- pH: 7.2 (abnormal)
- HCO3: 38 mmol/L (normal)
- PCO2: 56 mmHg (abnormal)
Given these findings, the correct answer is:
D. Metabolic acidosis
**Why Each Wrong Option is Incorrect:**
A. Hypercapnia (Option A): A normal PCO2 value is <45 mmHg, while the patient's PCO2 is 56 mmHg, indicating respiratory alkalosis (elevated PCO2) rather than hypercapnia (elevated CO2). B. Hypocapnia (Option B): A normal PCO2 value is <45 mmHg, while the patient's PCO2 is 56 mmHg, indicating respiratory acidosis (decreased PCO2) rather than hypocapnia (decreased CO2). C. Hyperventilation (Option C): The patient does not demonstrate the classic signs of hyperventilation (e.g., respiratory alkalosis, elevated pH) but rather exhibits respiratory acidosis (elevated PCO2). The patient presents with a combination of respiratory acidosis and hypocapnia (lowered CO2 levels), which is indicative of a condition known as respiratory acidosis. This occurs due to the accumulation of CO2 in the blood, leading to decreased pH and increased PCO2, as seen in the patient's blood gas analysis. **Clinical Pearl:** Understanding the patient's respiratory acidosis and hypocapnia is crucial for accurate diagnosis and appropriate management. Adequate ventilation and treatment can help reverse these abnormalities and improve the patient's condition. In conclusion, the patient demonstrates respiratory acidosis and hypocapnia, leading to a high PCO2 (56 mmHg) and a low pH (7.2). This combination of findings is indicative of respiratory acidosis, a condition resulting from an imbalance in the patient's respiratory system, specifically the accumulation of carbon dioxide (CO2) in the blood. **Why Option D is Correct:** The correct answer, D (metabolic acidosis, low