Shock

Question 1

What is shock?

Answer 1

Clinical syndrome of tissue hypoperfusion due to circulatory failure. It is common, life-threatening and acute

Question 2

What does inadequate perfusion cause?

Answer 2

• Systemic acidosis, further worsening global enzyme function and cellular performance
• Micro-capillary thrombus with patchy tissue injury (image shows micro-circulatory changes in health-A and in septic shock-B) and even large vessel thrombus with organ infarction
• Eventual cellular necrosis results in mortality
• In survivors, a degree of tissue injury may be irreversible, contributing to chronic mortbidity

Question 3

How is shock recognised?

Answer 3

1. Mottling of the skin
2. GCS <15, confusion, agitation
3. Urine output <0.5ml/kg/hr (oliguria)

Question 4

How is shock confirmed?

Answer 4

Lactate levels - >2mmol/L arguably diagnostic >4mmol/L significant mortality

Question 5

What is the mechanism of action in cardiogenic shock?

Answer 5

1. Reduced force of cardiac contraction and stroke volume and therefore cardiac output and mean arterial pressure
2. Compensatory increase in SVR, resulting in cool, clammy peripheries

Question 6

How is cardiogenic shock treated?

Answer 6

• HR - drugs +/- cardioversion if arrhythmia, drugs +/- dialysis if poisoning
• Stroke volume - drugs +/- PCI if MI, drugs if cardiomyopathy, drugs +/- surgery if valve failure

Question 7

What is obstructive shock?

Answer 7

1. Obstruction to cardiac outflow - otherwise similar to cardiogenic shock
2. Evidence of raised JVP and distended neck veins may be prominent

Question 8

How is obstructive shock treated?

Answer 8

• Cardiac tamponade - pericardiocentesis if trauma, thoracotomy +/- surgery if aortic dissection
• Tension pneumothorax - thoracentesis if trauma, thoracostomy +/- surgery if pleural pathology
• Pulmonary embolus due to stasis- anti-coagulation +/- thrombolysis or direct lysis

Question 9

What is the mechanism of action in hypovolaemic shock?

Answer 9

1. Reduced blood volume
2. Lower venous return to the heart
3. Reduced force of cardiac contraction and cardiac output

Question 10

If someone had a volume loss of >40%=over 2000ml, what would you expect their ABCDE to show?

Answer 10

• A + B = resp rate >35
• C = heart rate >140
• C = decreased blood pressure
• D = lethargic
• E = urine output negligible

Question 11

How is hypovolaemia treated when the cause is haemorrhage?

Answer 11

• Temporising measures - pressure, splint, binding
• Find and stop bleeding - endoscopy, surgery
• Cross-match, blood, blood products

Question 12

How is hypovolaemia treated when dehydration is the cause?

Answer 12

1. Fluids, electrolytes if GI loss
2. Specialist unit care if burns
3. Steroids/insulin if renal/cellular loss e.g. DKA or Addisonian crisis

Question 13

What is distributive shock?

Answer 13

1. Reduced systemic vascular resistance due to vasodilatation with warm, red peripheries
2. Reduced mean arterial pressure
3. Compensatory increase in cardiac output

Question 14

What are some of the inflammatory causes of distributive shock and how are these managed?

Answer 14

1. Sepsis - antibiotics +/- NA
2. SIRS, including pancreatitis and burns - supportive therapy
3. Anaphylactic shock - adrenaline

Question 15

How is a neurogenic cause of distributive shock managed?

Answer 15

• Spinal cord damage - neurosurgery
• Iatrogenic (spinal/epidural) - support +/- vasopressors