Circulatory shock

Question 1

What is circulatory shock?

Answer 1

Profound failure of the circulatory system that leads to poor perfusion of vital organs

Question 2

What is in practice shock ?

Answer 2

Low blood pressure and the physiological consequences

Question 3

What is the normal anatomy of the blood vessels ?

Answer 3

Blood 
Lumen 
Endothelium 
Basal lamina
Smooth muscles 
Interstitial collagen

Question 4

What is the normal blood arterial pressure of the blood? and is the arterial blood greater or lower than the venous blood pressure?

Answer 4

120/80

Lower

Question 5

What does normal arterial blood pressure depend on?

Answer 5

Sufficient blood present (5 litres)
Smooth muscles in blood vessels having certain tone
Pumping blood by heart

Question 6

What effects would each of the criteria for normal blood flow have if they were not followed?

Answer 6

Insufficient blood present in the blood:

• vessel then blood vessel would collapse
• the blood pressure would decrease and become uncontrollable

Tone of smooth muscle around blood vessel decreasing:

• Blood vessel dilates
• If the tone falls too low then the blood pressure drops

Heart does not pump enough blood:
- Blood pressure drops

Question 7

How does the body detect blood flow, blood pressure and oxygen?

Answer 7

By the presence of two carotid bodies, one on either side of the neck. These carotid bodies contain cells that sense the partial pressure of oxygen of the blood flowing through the artery.

Question 8

What happens if the blood pressure in the body drops and how will our bodies respond to this change?

Answer 8

Low blood pressure means that the partial pressure of oxygen will decrease. The carotid bodies which contain baroreceptors will release nerve impulses that will be send to the brain stem and then the brain stem will send nerve impulses through the sympathetic autonomic nervous system to the beta 1 receptors on the pacemaker and cardiac muscle of the heart leading to the heart to increase the heart rate and force of contraction

Question 9

What is the physiological response to low blood pressure?

Answer 9

Increase in pulse rate

Question 10

What are the functions of the brain stem as far as the circulatory system is concerned?

Answer 10

Increase pulse and force of contraction by sending nerve impulses or by instructing the adrenal glands to release adrenaline which acts on the heart if the pressure of blood decreases
increase the tone of the smooth muscle (vascular tone) in the limbs and abdomen resulting in sufficient blood flowing around the heart, lungs and brain which are vital organs,

Question 11

What are the key features of circulatory shock ?

Answer 11

Fast pulse (>100) with low blood pressure (60/40)

Question 12

What are the three main types of septic shock and which is the most common?

Answer 12

1. Hypovolaemic
2. Septic
3. Cardiogenic

Question 13

What is an example of hypovolaemic shock?

Answer 13

Case in which a woman has her rib being broken and penetrating through the spleen, where bleeding is caused and there is loss of 2 Litres of blood into the abdomen. This means that less blood will be present in blood vessels in spleen and the vessels will collapse. This means that slowly no blood will be entering the inferior vena cava, which will collapse as well and its venal pressure will fall to virtually zero. As no blood is present in the vena cava, the right hand side of the heart will receive almost no blood, which means that lungs, the brain and other parts of the body will receive less blood.
Systemic blood pressure falls because blood will not come out of the heart
Carotid arteries pick up low blood pressure and cause pulse rate to increase.

Question 14

What are the various signs that the carotid arteries cause as a response to low blood pressure?

Answer 14

Rapid breathing
Increase pulse
Patient feels ill
Pale, sweaty skin

Question 15

How is hypovolaemic shock recognised and dealt with in hospitals?

Answer 15

Tender abdomen
BP 60/40, HR 120
Abdominal trauma
Transfused blood and operation to remove spleen

Question 16

What are characteristics of hypovolaemic shock?

Answer 16

Low blood pressure due to severe reduction of blood in the circulation
Fast pulse as physiological response to low blood pressure
Unaffected hart

Question 17

What is a case with cardiogenic shock and how can it be treated?

Answer 17

Heart starts failing and can no longer pump enough blood to maintain blood pressure
Venous pressure is normal or increased
Treatment: heart function enhancement drugs

Question 18

How can septic shock be caused?

Answer 18

Urinary tract infection where bacteria infect kidney and move into the blood. Then immune response takes place where general vasodilation occurs and causes blood to flow to the veins in the legs. This means that there will be less blood flowing to the brain and rest of the body, which at start leads to reversible change but will then later on lead to permanent damage of infarct formation. Decreased flow of blood to kidneys is also reversible at start but then It can lead to renal failure.

Question 19

What are the features of septic shock?

Answer 19

Generalised vasodilation which is followed by decreased blood pressure and high heart rate

Question 20

What are the two complications caused by shock?

Answer 20

1. Reversible and then severe brain damage - ischaemic infarction to brain tissue
2. Reversible and then after 2 to 3 hours permanent damage to kidneys- ischaemic necrosis of renal tubules