Shock

Question 1

Types of shock

Answer 1

Hypovolemic
Cardiogenic
Mechanical
Septic
Anaphylactic

Question 2

Definition of shock

Answer 2

Acute circulatory failure resulting in inadequate tissue perfusion and insufficient oxygen supply to the cells

Question 3

Causes of hypovolemic shock

Answer 3

External blood loss
Hidden blood loss (intrathoracic/intrabdominal)

Others:
Diarrhoea and Vomiting
Oedema
Cutaneous (burns)
Polyuria

Question 4

Changes in the circulatiory system due to hypovolemic shock

Answer 4

Loss of circulating volume
Reduced venous return and cardiac fillinf

Therefore reduced SVand reduced CO

This reduces BP and oxygen delivery

Impaired cellular function

Question 5

Neuroendocrine response to hypovolemic shock

Answer 5

Reduced blood volume and blood pressure reduces stretch of aortic and carotid baroreceptors, reduced blood flow to chemoreceptors.

Causes reflex increase in sympathetic tone and reduces parasympathetic input.

Results in increased heart rate (tachycardia)
Release of catecholamines from adrenals
Vasoconstriction (increased TPR to maintain bp, increased cardiac filling)

Activation of RAAS to incerase water retention

Produces increase in cardiac output and SVR. Blood flow re-distributed to vital organs

Question 6

Clinical features of hypovolemic shock

Answer 6

Skin: cold, clammy, pale, slow capillary refill

Circulation: tachycardia, initially reduced pulse pressure (systolic maintained, diastolic rises), collapsed veins (severe)

Brain: confusion, restlessness, loss of consciousness

Respiration: tachypnoea

Altered brain and kidney function most significant

Question 7

What are the metabolic changes that occur in hypovolemic shock

Answer 7

Increased anaerobic metabolism: Lactate and H+ production causing metabolic acidosis

Hyperglycaemia - glucagon and cortisol released in stress response

Lack of O2 reduces ATP production, leads to failure of Na/K+ pump. Cell swelling, release of K+, activation of lysomal enzymes, Ca2+ entery and cell death

Question 8

Management of hypovolemic shock

Answer 8

High flow oxygen
Replacement of circulating volume (until bp is restored to normal limits)
Diagnosis and treatment of cause

Question 9

Causes of cardiogenic shock

Answer 9

Acute MI
Heart failure (more common)

Question 10

Clinical features of cardiogenic shock

Answer 10

Reduced contractility due to ischemia and infarction of the myocardium.

Low CO and high LVEDV

Results in pulmonary congestion - dyspnoea, crackles and wheeze, pulmonary oedema, pleural effusion

Eventually leads to RH failure - raised JVP, peripheral oedema

Question 11

Management of cardiogenic shock

Answer 11

Diagnosis - from history (IHD, chest pain), ECG, troponin

Treat with thrombolytics, angiography (stenting), high flow oxygen, analgesia, diuretics, IV fluids if necessary

Question 12

Causes of mechanical shock

Answer 12

Pulmonary embolism
Tension pneumothorax
Cardiac tamponade

Question 13

Pulmonary embolism

Answer 13

A mass in the pulmonary vessels that travels from a distant site and causes obstruction of blood flow.

Causes acute overloading of the right ventricle and hypovolemia of the LA and LV

Question 14

Diagnosis and treatment of PE

Answer 14

Pulmonary angiography
(V/Q scan, ECG)

Full resuscitation, anticoagulants, thrombolysis.

Question 15

Clinical presentation of PE

Answer 15

Crushing central chest pain
Dyspnoea
High venous pressure
Increased SVR

(DVT may be present)

Question 16

Tension pneumothorax

Answer 16

Abnormal collection of air in the pleural cavity that is markedly increased when a one-way valve is formed by an area of damaged tissue.

Increasing pressure collapses teh lung and pushes the mediastinum and heart to the other side.

Impairs respiration and circulation (raised intrathoracic pressure and deviated great vessels prevent cardiac filling)

Question 17

Presentation of pneumothorax

Answer 17

hypoxia, hypercarbia, respiratory distress, hypotension and tachycardia

Examination shows poor chest expansion, mediastinal shift away from the side of the pneumothorax (deviated trachea, displaced apex beat) and a hyperresonant thorax

Question 18

Treatment of tension pneumothorax

Answer 18

Immediate decompression and chest drain.

Tube inserted 2nd intercostal space, midclavicular line

Question 19

Cardiac tamponade

Answer 19

Compression of the heart due to fluid accumulation in the pericardium. Compresses the heart.

Question 20

Treatment of cardiac tamponade

Answer 20

Sub-xiphoid pericardiocentesis

Question 21

Physiology of septic shock

Answer 21

Inflammatory mediators released in severe sepsis cause vasodilation, intravascular coagulation and loss of circulating volume through leaky capillaries

Blood pools in dilated peripheries, reducing venous return and CO.

Blood pressure is reduced (diastolic pressure falls, wider pulse pressure)

Question 22

Clinical features of septic shock

Answer 22

Early: Vasodilation causes warm peripheries, low venous pressure (hypotension). bounding pulse, rapid capillary refill, (fever)

Late: cold peripheries, tachycardia, sweating

Question 23

Mangement of septic shock

Answer 23

Sepsis 6

Oxygenation, fluid resusctation, inotropic agent, vasoconstrictor support

Bacterial cultures
Antibiotics and surgical drainage

Question 24

Anaphylactic shock

Answer 24

Anaphylaxis is a serious allergic reaction that is rapid in onset (and may cause death)

Anaphylactic shock is associated with systemic vasodilation and increased capillary permeability that causes hypovolemia and low blood pressure

Question 25

Presentation of anaphylaxis

Answer 25

Within 30min exposure…

Erythema, urticaria, oedema, palloe/cyanosis

Tachcardia, hypotension

Rhinitis, bronchospasm, laryngeal obstruction, pulmonary oedema

Vomiting, diarrhoea, cramps

Question 26

Management of anaphylaxis

Answer 26

IM adrenaline asap
Fluid resuscitation
CPR
Steroids, antihistamines