A PaCO2 greater than 60 mm Hg supports a diagnosis of what condition?

A PaCO2 greater than 60 mm Hg is indicative of hypercapnia, which means there is an excessive level of carbon dioxide in the bloodstream. This condition is commonly observed in various respiratory problems where the lungs are unable to adequately ventilate, leading to carbon dioxide retention.

The threshold of 60 mm Hg is particularly significant because it often coincides with severe respiratory impairment. This high level is typically associated with acute respiratory failure, where the respiratory system fails in oxygenation and/or clearing carbon dioxide.

In evaluating the choices, while chronic obstructive pulmonary disease (COPD) can also lead to elevated PaCO2 levels, it doesn't definitively indicate an acute situation. Brain death is a condition where the entire brain ceases to function, and while it can lead to elevated PaCO2, it is not the most direct diagnosis supported by isolated high levels of carbon dioxide. Pneumonia can cause difficulties in ventilation but might not necessarily result in such elevated levels of PaCO2 unless it leads to complete respiratory failure.

Therefore, the measurement of PaCO2 greater than 60 mm Hg is most commonly associated with acute respiratory failure, which is characterized by the inability to maintain effective gas exchange and requires immediate medical attention.