The lab report of a patient is detailed below: PH 7.12 , HCO3-,1mmol/L , PCO2 | 18mm Hg | Which of the follow… - AIIMS Jodhpur SNO-2023

AIIMS Jodhpur SNO-2023

Medical & Surgical Nursing

Hard

Appeared in: AIIMS Jodhpur SNO-2023

Explanation

The patient's pH of 7.12 is below the normal range of 7.35-7.45, indicating a state of acidosis.
The bicarbonate (HCO₃⁻) level is 1 mmol/L, which is significantly lower than the normal range of 22-26 mmol/L. A low HCO₃⁻ is the hallmark of a metabolic acidosis.
Using the ROME (Respiratory Opposite, Metabolic Equal) method, the pH is low and the HCO₃⁻ is also low (moving in an equal or same direction), confirming a metabolic origin.
The partial pressure of carbon dioxide (PCO₂) is 18 mm Hg (normal 35-45 mm Hg). This low value indicates the respiratory system is hyperventilating to blow off CO₂ and compensate for the metabolic acidosis.

Option A: Metabolic alkalosis is characterized by a high pH (above 7.45) and a high HCO₃⁻ (above 26 mmol/L). The patient's values are the opposite.
Option C: Although the PCO₂ is low, the pH is also low (acidic). In primary respiratory alkalosis, the pH would be high (alkalotic). The low PCO₂ in this case is a compensatory response, not the primary disorder.
Option D: Respiratory acidosis is characterized by a low pH and a high PCO₂ (above 45 mm Hg) due to CO₂ retention. The patient's PCO₂ is low, not high.

Visual 1: Flowchart - A step-by-step flowchart for ABG interpretation (Check pH -> Check PCO₂ -> Check HCO₃⁻ -> Determine primary disorder and compensation). This visual simplifies the diagnostic process.
Visual 2: Diagram - The ROME mnemonic chart, visually linking the direction of pH, PCO₂, and HCO₃⁻ to the four primary acid-base disorders.
Visual 3: Illustration - An illustration of Kussmaul respirations (deep, rapid breathing) to show the body's physical attempt to compensate for metabolic acidosis.

Clinical Relevance

Nursing practice connection: Knowing Interpretation of Arterial Blood Gas (ABG) results to identify primary acid-base disorders helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Recognizing metabolic acidosis is critical as it can be life-threatening. Common causes include diabetic ketoacidosis (DKA), sepsis, renal failure, and severe diarrhea.
Nurses must monitor for signs of compensation, such as Kussmaul respirations (deep, rapid breathing), which is the body's attempt to exhale CO₂ and correct the acidosis.
Metabolic acidosis often causes a shift of potassium out of cells, leading to hyperkalemia. Nurses should monitor the patient's potassium levels and be vigilant for cardiac dysrhythmias.

How to Approach the Question

First, look at the pH. Classify it as acidosis (less than 7.35), normal (7.35-7.45), or alkalosis (greater than 7.45). Here, 7.12 is acidosis.
Next, examine the PCO₂ (the respiratory component). A value outside the normal 35-45 mm Hg indicates a respiratory issue. Here, 18 mm Hg is low (alkalotic).
Then, examine the HCO₃⁻ (the metabolic component). A value outside the normal 22-26 mmol/L indicates a metabolic issue. Here, 1 mmol/L is very low (acidotic).
Compare the components to the pH to find the primary cause. The component that matches the pH's state (acidosis or alkalosis) is the primary cause. Here, the low (acidotic) HCO₃⁻ matches the low (acidotic) pH. Therefore, it is metabolic acidosis.
Finally, check for compensation. The PCO₂ is moving in the opposite direction of the pH, indicating the respiratory system is trying to compensate.

Concept Tested & Keywords

Concept Tested: Interpretation of Arterial Blood Gas (ABG) results to identify primary acid-base disorders.
Stem keywords: lab report, PH 7.12, HCO3- 1mmol/L, PCO2 18mm Hg, acid base disorder
Lead-in keywords: Which of the following
Clinical cues: pH below 7.35 indicates acidosis.
Clinical cues: HCO3- below 22 mmol/L indicates a metabolic component.

Q6DTkfiXX9CFqSkrwO7GfZ