Which vital sign is NOT typically examined by a respiratory therapist to evaluate ventilation?

The vital sign that is not typically examined by a respiratory therapist to evaluate ventilation is urine output. In the context of respiratory care, ventilation assessment primarily focuses on the effectiveness of breathing and the gas exchange occurring in the lungs. This is evaluated through various measurements and observations, such as chest movement, breath sounds, and the partial pressure of carbon dioxide in the blood (PaCO2).

Chest movement provides insight into the mechanics of breathing and whether the patient has adequate lung expansion and contraction. Observations of breath sounds help in identifying possible airway obstructions or abnormal lung conditions that affect ventilation. PaCO2 measurements reflect how well carbon dioxide is being expelled, which is critical for assessing the effectiveness of ventilation.

Urine output, however, is more relevant in contexts such as renal function or fluid balance, rather than respiratory function. As such, it does not directly provide information on a patient's ventilation status, making it the correct choice in this question.