Shock

Question 1

what is the definition of shock?

Answer 1

Acute tissue hypoperfusion due to circulatory failure

Question 2

briefly describe the basic physiology of shock

-what 4 mechanisms effect the mean arterial pressure?

Answer 2

Mean arterial pressure drops (50-60 mmHg)

slow blood flow to organs (possible thrombus)

Inadequate perfusion of cellular metabolic requirements
–> acidosis and lactate formation

-HR & SV = CO
CO & systemic vascular resistance = Mean arterial pressure

Question 3

Give 3 consequences of inadequate perfusion?

Answer 3

systemic acidosis
(worsens enzyme function and cellular performance) 

Microcapillary thrombus with patchy tissue injury and even large vessel thrombus with organ infarction

eventual cellular necrosis results in mortality

Question 4

What are the signs of shock? (3)

Answer 4

Mottling

Glasgow coma score <15- confusion/agitation

Reduced urine output <0.5ml/kg/h

Question 5

Hoe do you confirm Shock?

Answer 5

Lactate levels

> 2mmol/l of lactate highly suggestive of shock

Question 6

Cardiogenic shock

• physiological cause?
• clinical sign?
• treatment?

Answer 6

-Reduced force of cardiac contraction so
Reduced SV so
Reduced CO so
Reduced Mean arterial pressure

-Cool clammy peripheries due to increased SVR

-depends on cause 
Arrythmia- cardioversion
Poisoning- Dialysis
MI-PCI
cardiomyopathy- drugs
Valve failure- surgery

Question 7

Obstructive shock

• cause?
• clinical signs?
• treatment?

Answer 7

• Obstruction to cardiac outflow e.g. cardiac tamponade, tension pneumothorax, PE
• evidence of raised JVP and Distended Neck veins due to venous back pressure

-again depends on cause
cardiac tamponade- pericardiocentesis/thoractomy
Tension pneumothorax- thoracocentesis/thoractomy
PE- anticoagulation/thrombolysis

Question 8

Hypovolaemic shock

• describe the physiology
• clinical sign? (2)
• what obs should be tested in suspected haemorrhage?
• treatment?

Answer 8

-reduced blood vol
Lower venous return to heart
reduced force of cardiac contraction and CO

-tachycardia
cool, clammy peripheries

-RR
HR
BP
Mental state
Urine output

-haemorrhage
(temporising measures, Find and stop bleeding, cross-match blood and blood product)
Dehydration
(fluids & electrolytes, specialist unit care steroids/insulin)

Question 9

Distributive shock

• describe the physiology
• clinical sign?
• causes?
• memorise the rapid assessment table on slide 36

Answer 9

-Reduced systemic vascular resistance due to vasodilation
reduced mean arterial pressure
compensatory increase in CO

-Warm, red peripheries
bounding, hyper dynamic circulation

-most commonly sepsis

Question 10

What result from a fluid challenge suggests poor systolic function?

Answer 10

no increase in SV after volume challenge