Which disturbance classification is associated with increased bicarbonate and normal PCO2?

The classification of disturbances in acid-base balance can provide insights into the underlying physiological processes in the body. An increased bicarbonate level accompanied by a normal partial pressure of carbon dioxide (PCO2) indicates a metabolic process rather than a respiratory one.

In metabolic alkalosis, the primary disturbance is an increase in bicarbonate concentration, often due to factors such as excessive vomiting, diuretic use, or other conditions that lead to a loss of hydrogen ions or a gain of bicarbonate. The normal PCO2 suggests that the respiratory system is compensating for this metabolic disturbance appropriately, as it does not need to alter the carbon dioxide levels in response to the increase in bicarbonate.

In contrast, other conditions such as respiratory acidosis or respiratory alkalosis would typically show altered PCO2 levels, reflecting changes in ventilation. Similarly, metabolic acidosis would present with decreased bicarbonate levels, not increased.

By recognizing these patterns, it becomes clear that the observed increase in bicarbonate along with a normal PCO2 distinctly characterizes metabolic alkalosis, affirming its classification as the correct answer.