Which of the following symptoms may suggest a patient is entering shock?

Restlessness is a significant symptom that may indicate a patient is entering shock. As the body begins to struggle with perfusion and oxygen delivery due to a drop in blood volume, blood pressure, or cardiac output, the brain can experience a lack of adequate oxygen. This can lead to mental status changes, including anxiety and restlessness, as the patient becomes increasingly aware of distress within their body. In a state of shock, the body's compensatory mechanisms are activated, which can produce non-specific responses like restlessness as the patient senses they are not well.

The other options do not align with classic signs of shock. Increased temperature can sometimes occur, but is not a primary indicator and can be associated with infection rather than shock itself. A cheery demeanor is often not consistent with a state of shock as patients typically present with anxiety or confusion due to compromised circulation. A regular heart rate can also be misleading; while it may seem normal, patients in shock often exhibit tachycardia as a compensatory mechanism. Thus, restlessness stands out as a key sign of a patient potentially entering shock.