Medical Laboratory Scientist ASCP Practice Exam 2025 – Complete Study Guide

In respiratory acidosis, the primary issue is an increase in carbon dioxide (CO2) in the blood due to hypoventilation or inadequate gas exchange, leading to a decrease in blood pH (acidosis). As CO2 levels rise, they react with water to form carbonic acid, causing an increase in hydrogen ion concentration and thus a decrease in pH.

As a result, the partial pressure of carbon dioxide (pCO2) will be elevated, reflecting the respiratory component of the acid-base disturbance. Concurrently, bicarbonate (HCO3-) might initially remain normal as the metabolic compensation may take time to develop, leading to increased values as the kidneys begin to retain bicarbonate to help neutralize the acidity. However, in acute respiratory acidosis, bicarbonate may not have increased significantly yet.

In this context, the interpretation of values points to an increase in pCO2 and unchanged or slightly changed HCO3- while the pH remains low. Thus, saying that all values except pH increased accurately describes the changes happening during respiratory acidosis, as it is characterized by decreased pH, increased pCO2, and potentially stable HCO3- depending on the duration and extent of the compensation. The understanding of