What change in vital signs might indicate pain in a patient without respiratory or cardiovascular disease?

An increase in heart rate can be a significant indicator of pain in a patient who does not have underlying respiratory or cardiovascular disease. When a person experiences pain, the body activates its stress response, also known as the "fight or flight" response. This response includes the release of stress hormones such as adrenaline, which can lead to an increase in heart rate.

The physiological rationale behind this response is that an elevated heart rate helps to ensure that more oxygenated blood is delivered to vital organs and tissues in times of distress, such as when a person is in pain. Additionally, the body may increase heart rate to manage the metabolic demands that come with experiencing pain.

It's important to note that while other vital signs can also change due to pain, an increased heart rate is a common and reliable indicator in clinical practice, especially in patients who do not exhibit other issues related to their cardiovascular or respiratory systems.