Question

A hyperventilating patient has ABG value of pH = 7.53, pCO₂ = 20 mmHg, HCO₃ = 26 meq. What is the diagnosis?

• A. Respiratory acidosis
• B. Respiratory alkalosis
• C. Metabolic acidosis
• D. Metabolic alkalosis

Hint:

Assess the pCO₂ to determine whether the primary disturbance is respiratory or metabolic.

Answer 1

The Correct Option is B

Approach using the ROME mnemonic (Respiratory Opposite, Metabolic Equal):

Given: pH = 7.53, pCO₂ = 20 mmHg, HCO₃ = 26 meq, history of hyperventilation.

Step 1: pH = 7.53 -- alkalotic (pH > 7.45).

Step 2: Apply ROME -- in Respiratory disorders, pH and pCO₂ move in OPPOSITE directions. pH is high (alkalotic) and pCO₂ is low -- they move in opposite directions, confirming a respiratory origin.

Step 3: Since pH is high and primary cause is respiratory, this is Respiratory Alkalosis.

Step 4: HCO₃ = 26 meq is near normal, indicating no significant metabolic compensation yet -- consistent with acute respiratory alkalosis.

Mechanism: Hyperventilation causes excess CO₂ to be blown off, reducing pCO₂ and shifting the equilibrium: CO₂ + H₂O --> H₂CO₃ --> HCO₃^- + H⁺, resulting in decreased H⁺ and raised pH.

\[\boxed{\text{Respiratory Alkalosis}}\]