Session 5 - Shock

Question 1

what is haemodynamic shock

Answer 1

acute condition of inadequate blood flow throughout the body so that there is a catastrophic fall in arterial blood pressure

Question 2

a reduction in what causes shock

Answer 2

cardiac output or total peripheral resistance

Question 3

what does a reduction in cardiac output cause

Answer 3

• pump failure
• loss of blood volume
• pump not filling properly

Question 4

what does a fall in peripheral resistance cause

Answer 4

excessive vasodilation

Question 5

what is cardiogenic shock

Answer 5

the ventricles don’t empty properly (pump failure)

Question 6

what is mechanical shock

Answer 6

the ventricles don’t fill properly

Question 7

what is hypovolaemic shock

Answer 7

reduced blood volume leads to poor venous return

Question 8

what causes cardiogenic shock

Answer 8

• MI causing damage to LV
• arrthythmias
• heart failure

Question 9

how does tachycardia cause cardiogenic shock

Answer 9

if the heart beats too fast then there is not enough time for the heart to fill and empty

Question 10

what are the effects of cardiogenic shock

Answer 10

tissues are poorly perfused

Question 11

what type of shock does cardiac tamponade lead to

Answer 11

mechanical shock

Question 12

what happens to the central venous pressure in cardiac tamponade

Answer 12

it increases as the blood returning cant fill the heart

Question 13

how does a pulmonary embolism cause mechanical shock

Answer 13

• occludes a large pulmonary artery giving a high pressure.
• the RV cant empty which raises the venous pressure
• reduced heart return to the left heart
• left arterial pressure is lowered leading to shock

Question 14

how does an embolism reach the lungs

Answer 14

portions of a thrombosis in the legs breaks off and travels in the venous system to the lungs

Question 15

what most commonly causes hypovolaemic shock

Answer 15

haemorrhage

Question 16

what proportion of blood must be lost to cause hypovolaemic shock

Answer 16

20-30% too show sign

30-40% for a serious response

Question 17

how does a haemorrhage cause hypovolaemic shock

Answer 17

the venous pressure falls which causes the cardiac output to fall by starlings law.

Question 18

what is done by the body to compensate for a haemorrhage

Answer 18

there is increased sympathetic stimulation causing tachycardia which increases the force of contraction and causes vasoconstriction

Question 19

during hypovolaemic shock what happens to the net movement of fluid in the capillaries

Answer 19

fluid moves into the capillaries due to a lower hydrostatic pressure

Question 20

what does a patient in hypovolaemic shock have

Answer 20

• weak pulse
• tachycardia
• pale skin
• cold, clammy extremities

Question 21

what can severe burns, diarrhoea or vomiting cause

Answer 21

hypovolaemic shock

Question 22

what are the dangers of compensating for hypovolaemic shock

Answer 22

vasoconstriction will cause tissue damage by hypoxia

this causes the release of chemical mediators which cause vasodilation causing bp to fall more

Question 23

what type of shock result from a decrease in TPR

Answer 23

distributive shock

Question 24

what is distributive shock

Answer 24

where there is profound vasodilation as the volume of circulation has increased but the blood volume is normal

Question 25

what are the 2 types of distributive shock

Answer 25

• anaphylactic

- toxic shock

Question 26

what is toxic/septic shock

Answer 26

• persisting hypotension requiring treatment to maintain blood pressure despite fluid resuscitation due to shock

Question 27

what causes septic shock

Answer 27

endotoxins released by circulating bacteria cause vasodilation through an excessive inflammatory response causing a decrease in TPR

Question 28

why does a patient which shock have tachycardia

Answer 28

baroreceptors detect a decrease in pressure and so increase heart rate and stroke volume compensate

Question 29

what is anaphylactic shock

Answer 29

severe allergic reaction due to the release of histamine from mast cells causing vasodilation

Question 30

what should be administered to someone suffering from an anaphylactic shock

Answer 30

adrenaline - causes vasoconstriction vis alpha 1 adrenoreceptors