Question

Case Study
Horatio Salvatore is a 77-year-old bachelor who was brought to the emergency room one evening. He had seen bright red blood in his stool, which he attributed to hemorrhoids; however, the bleeding continued all day, and by supper, he could no longer ignore it. Horatio does not smoke or drink alcoholic beverages. He takes aspirin, as needed, for arthritis, sometimes up to eight tablets daily.
In the emergency room, Horatio was light-headed, pale, cold, and very anxious. His hematocrit was 30% (typically ~42 for men). The table below shows his blood pressure and heart rate in the lying (supine) and upright (standing) positions.
Mr. Salvatore's Blood Pressure and Heart Rate     
Parameter   Lying Down (Supine)   Upright (Standing)
Blood pressure   92/61   76/45     
Heart rate   107 beats/min   134 beats/min

At the ER, a colonoscopy showed that the bleeding came from diverticula, which had stopped at the time of the colonoscopy. Because of the blood lost, Mr. Salvatore received two units of whole blood and was admitted for observation.

Case Study Questions
1.   What is the definition of circulatory shock? What are the major causes?
Circulatory shock is a condition defined by the lack of substrates suitable for cellular respiration. It can be caused by any conditions that results in reduced blood flow, such as heart failure, profuse bleeding, or low blood volume due to dehydration.

2.   Why was Mr. Salvatore’s arterial pressure lower in the upright position than in the lying (supine) position?
Mr. Salvatore already has reduced blood volume due to bleeding and aspirin consumption. Therefore in an upright position, his body must have a difficult time compensating for the effects of gravity with respect to blood circulation. In the supine position, his blood circulation is more easily dispersed throughout his extremities.

3.   Why was his heart rate was elevated when he was supine. Why? Why was his heart rate even more elevated when he was upright?
When you’re standing you have gravity forcing the blood down into the extremities so the heart has to work harder to return the venous blood. His heart rate was elevated because he had low blood volume due to the excessive bleeding so his heart had to work harder to compensate for the low tissue oxygenation and low blood pressure.

Answer 1

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

Circulatory shock is a condition defined by the lack of substrates suitable for cellular respiration.

Shock is a critical condition where the organs lacks sufficient blood flow leading to poor oxygenation and nourishment.

The causes are mainly loss of blood and fluids of the circulation.

• Bleeding as in accidents
• Bleeding from other injuries
• Internal bleeding, such as in the gastrointestinal tract
• Burns
• Severe Diarrhea
• Excessive perspiration
• Vomiting

2. Why was Mr. Salvatore’s arterial pressure lower in the upright position than in the lying (supine) position?

Normally, when a position change occurs, standing causes blood pooling of 500-1000ml in the lower extremities. The drastic decrease in the blood pressure will be managed by increased sympathetic outflow, increasing vascular resistance. This in turn increases venous return and cardiac output. These normal compensatory mechanisms cause systolic BP to decrease by 5-10mm Hg, and increase diastolic BP by 5-10mmof Hg. The pulse rate also will be increases 10-25 beats/minute.

These compensatory mechanisms fail when: the intravascular volume is very low, dysfunctioning of autonomic nervous system, reduced venous return or inability to increase cardiac output.

Mr Salvatore had severe bleeding , he might have lost large intravascular fluid volume. The decreased hematocrit values also support this. . Also the consumption of Aspirin added to his issue reducing the platelet to function properly. The compensatory mechanisms of position changes are not functioning properly.

Also the patient needs to be evaluated for cardiac functioning, if the condition persists even after transfusion.

3.    Why was his heart rate was elevated when he was supine. Why? Why was his heart rate even more elevated when he was upright?
   

As a normal compensation to change in position to standing, the heart rate increases 10-25 beats/minute. Here the heart rate increased this almost 27 beats/minute because of the very low circulatory olume. When you’re standing you have gravity forcing the blood down into the extremities so the heart has to work harder to return the venous blood. His heart rate was elevated because he had low blood volume due to the excessive bleeding so his heart had to work harder to compensate for the low tissue oxygenation and low blood pressure.