Acid Base Disorders: Respiratory Acidosis

Correct answer: D

EXPLANATION

This patient has symptoms and signs of chronic obstructive pulmonary disease, specifically chronic bronchitis.
Symptoms and signs include cough, sputum production and dyspnea with exertions. Patients tend to be stocky or overweight, as the case here.

Auscultation will reveal wheezes and rhonchi.This patient is retaining CO2, since his pCO2 is elevated. CO2 is in equilibrium with carbonic acid. An increase in CO2 will shift the Henderson Hasselbalch equation to the left, resulting in acidosis. Since the cause of the primary problem is respiratory, e.g. retention of CO2, this is a
respiratory acidosis.

This is reflected in the pH being reduced as well. Metabolic acidosis (choice a, choice b) is incorrect because the primary problem is not due to a administration of acid, excess metabolic acid formation, or loss of base. Although the bicarbonate level is abnormal in this patient, that is due to metabolic compensation for the respiratory acidosis.

Alkalosis (choice c, choice e) are incorrect because his pH is acidotic. Although compensatory mechanisms can bring the pH towards the normal range, compensatory mechanisms will never overshoot.

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