Blanche Devereaux is a 78-year-old widow who was brought to the emergency room one evening by her sister. Earlier in the day, she had seen bright red blood in her stool. She continued with her daily activities. However, the bleeding continued all day. By dinnertime, she could no longer ignore it. Blanche takes aspirin, as needed, for arthritis, sometimes up to 12 tablets daily. In the emergency room, she was light-headed and her skin was pale and cool to the touch. Her hematocrit was 26% (normal for women, 35%-45%). The ER doctor ordered orthostatic vital signs. Below are the results of the test:

Measurement	Supine	Standing
Blood Pressure	88/60	74/46
Heart Rate	106 bpm	130 bpm

1. What is the definition of circulatory shock? What are some causes of circulatory shock?

2. After blood loss, what is the fundamental problem in shock? Why does shock occur due to loss of blood?

3. Calculate Mrs. Devereaux’s pulse pressure and mean arterial pressure while supine and standing.

4. What was the compensatory mechanism that leads to her heart rate being fast in both positions?