Final answer:
A rapid, thready pulse (option C) is an early indicator of internal bleeding in non-trauma patients, reflecting potential hypovolemic shock which may require urgent medical treatment.
Step-by-step explanation:
In non-trauma patients, an early indicator of internal bleeding is a rapid, thready pulse. The body reacts to hemorrhage by initiating compensatory mechanisms to increase blood pressure and maintain blood flow. However, symptoms such as dizziness upon standing (orthostatic hypotension), rapid, shallow breathing, and a decreasing blood pressure can also be observed as the condition progresses. The rapid, thready pulse reflects a state of hypovolemic shock typically due to hemorrhage.
A thready pulse is weak and rapid and suggests that the circulatory system is struggling to maintain adequate blood flow. It is essential to recognize these signs and initiate appropriate medical intervention quickly, including intravenous fluid replacement and possibly vasoactive drugs to maintain blood pressure.