Which of the following is a sign of respiratory failure?

Confusion or altered mental status is a significant sign of respiratory failure because it indicates that the brain is not receiving adequate oxygen, which can be a result of insufficient gas exchange in the lungs. When the respiratory system is unable to meet the body’s oxygen demands or effectively remove carbon dioxide, this can lead to hypoxia (low oxygen levels) or hypercapnia (elevated carbon dioxide levels). Both of these conditions can affect brain function, leading to confusion, disorientation, or a reduced level of consciousness. Monitoring mental status is crucial in assessing the severity of respiratory issues and identifying respiratory failure, particularly in patients who may present with other signs and symptoms.

While an increased respiratory rate might initially occur as a compensatory mechanism, it does not definitively indicate respiratory failure on its own since many factors can increase respiratory rates. A normal heart rate does not correlate with respiratory failure, as the heart rate may remain stable in some cases of respiratory distress. Clear lung sounds upon auscultation can indicate that there are no significant obstructions or fluid in the lungs, which might be expected in certain conditions but does not rule out respiratory failure. Hence, confusion or altered mental status is the most direct indicator of compromised respiratory function among the choices given.