Which vital sign change might be expected in a patient with severe dehydration?

In cases of severe dehydration, the body experiences a significant loss of fluids, which can lead to several compensatory physiological changes. One key response to dehydration is an increase in heart rate, known as tachycardia. This occurs because, with less circulating blood volume, the heart pumps faster to maintain adequate perfusion and oxygen delivery to vital organs.

The body's response to dehydration includes the activation of the sympathetic nervous system, leading to increased heart rate to compensate for the reduced stroke volume that results from decreased blood volume. This compensatory mechanism helps to maintain blood pressure and tissue perfusion despite the overall decrease in fluid volume.

In contrast, normal blood pressure might occur in some instances where compensatory mechanisms are still effective, but it does not directly indicate dehydration. Chest pain, while it may arise from various conditions, is not a direct physiologic response to dehydration itself, and decreased respiratory rate is not typically associated with dehydration; instead, it might be more influenced by other concurrent conditions. Therefore, the presence of an increased heart rate is a clear indicator of the body's compensatory attempt in response to severe dehydration.