Which vital sign is the last to change during shock?

• A. Heart rate
• B. Blood pressure
• C. Oxygen saturation
• D. Respirations

Answer: (B)

In shock, the body fights to preserve blood flow to the heart and brain, using compensatory mechanisms like speeding the heart and narrowing vessels. This keeps the heart rate up and breathing rate increases early to meet metabolic demands, so those signs change first. Oxygen saturation can remain near normal for a while because oxygen delivery to the lungs and tissues is still adequate at the outset. As compensation continues to struggle and perfusion worsens, those early signs may continue to shift, but blood pressure tends to stay within the normal range until late in the process. Only when the compensatory mechanisms fail does the blood pressure drop, signaling decompensation and the need for urgent intervention.