This document defines and describes different types of shock, including cardiogenic, hypovolemic, and septic shock. It discusses the pathogenesis, causes, stages and key features of each type. Cardiogenic shock is caused by low cardiac output due to myocardial damage or obstruction. Hypovolemic shock is caused by fluid loss leading to hypovolemia. Septic shock results from a severe bacterial or fungal infection and involves an inflammatory response and endothelial cell damage. Shock progresses through non-progressive, progressive and irreversible stages if left untreated, ultimately leading to multi-organ failure and death.

1. SHOCK
Dr. Salman Ansari
Dept. of Pathology
Kanachur Institute of Medical Sciences

2. Contents
● Definition
● Types of shock with examples
● Hypovolemic shock
● Cardiogenic shock
● Septic shock
● Stages of shock: non-progressive, progressive and
irreversible

3. Shock
Definition: pathological process characterised by
intense failure of the circulatory system to maintain
an appropriate blood supply to the microcirculation
● This results in life-threatening hypoperfusion to
vital organs

4. Types of shock
1. Cardiogenic
2. Hypovolemic
3. Septic
4. Less common types: neurogenic shock,
anaphylactic shock

5. Type Causes
Cardiogenic ● MII
● Ventricular rupture
● Arrhythmia
● Cardiac tamponade
● Pulmonary embolism
Hypovolemic Fluid loss(bleeding, vomiting,
diarrhoea, burns)
Septic Severe bacterial or fungal infections
Less common: neurogenic,
anaphylactic
Spinal cord injury, anesthetic accident

6. Cardiogenic shock
Definition: Shock due to low cardiac output as a result of:
- myocardial damage
- external compression of the heart
- obstruction to outflow of blood from ventricles
Causes:
● MI
● Ventricular rupture
● Arrhythmia
● Cardiac tamponade
● Pulmonary embolism

7. Pathogenesis of cardiogenic shock
Various causes of cardiogenic shock(e.g: MI)
↓
LV dysfunction
↓
Decreased cardiac output
↓
Decreased perfusion of tissues

8. Hypovolemic shock
Hypovolemia=abnormal decrease in volume of circulating blood
Definition: Shock due to low cardiac output as a result of:
- Loss of blood: massive hemorrhage
- Loss of plasma: severe burns
- Loss of fluid: vomiting, diarrhoea, severe gastroenteritis
Causes: Fluid loss due to:
● Hemorrhage
● Vomiting
● Diarrhoea
● burns

9. Pathogenesis of hypovolemic shock
Inadequate blood or plasma volume and fluid loss
↓
hypovolemia
↓
low cardiac output
↓
hypotension
↓
inadequate perfusion of tissue.

10. Septic shock
Definition: Shock due to severe sepsis with
hypotension
Causes:
● Infection by Gram-positive bacteria most
commonly. E.g: Staphylococcus aureus,
Streptococcus pneumoniae
● Gram-negative bacteria

11. Main factors contributing to septic shock
1. Inflammatory response:
Activation of neutrophils, macrophages and cytokine release
1. Endothelial cell activation and injury:
Increased vascular permeability → widespread edema
1. Pro-coagulant state:
endotoxin activates factor XII → activation of coagulation system
→ thrombosis of small vessels - complication called

12. 4. Metabolic abnormalities:
- hyperglycemia, insulin resistance
- Decreased glucocorticoid production - due to adrenal
gland insufficiency - life-threatening complication called
Waterhouse-Friderichsen syndrome(WFS)
5. Organ dysfunction: decreased contractility of the heart
and cardiac output → failure of multiple organs like liver,
lung, kidneys and heart → death
6. Immune suppression: hyperinflammatory state leads to
suppression of immune system

14. Pathogenesis of septic shock(short version)
Major factors contributing to septic shock are:
1. Inflammatory response: Activation of neutrophils,
macrophages and cytokine release
2. Endothelial cell activation and injury: Increased
vascular permeability → widespread edema
3. Pro-coagulant state: endotoxin causes activation of
coagulation system → Disseminated intravascular
coagulation(DIC)

15. 4. Metabolic abnormalities: hyperglycemia, insulin
resistance, adrenal gland insufficiency
5. Organ dysfunction: decreased cardiac output → failure
of multiple organs like liver, lung, kidneys and heart →
death
6. Immune suppression

16. Activation of host’s immune system:
neutrophils and cytokines released
Endothelial cell injury
Vasodilation and pooling of blood in
peripheries
↑ permeability: widespread edema
Decreased tissue perfusion
Multi-organ failure
Endotoxin
Activation of coagulation
Micro-thrombi - Disseminated
intravascular coagulation(DIC)
Tissue ischemia
Microbial products

17. Stages of shock
3 phases
1. Non-progressive (compensated/reversible) phase
2. Progressive phase
3. Irreversible phase

18. 1. Nonprogressive/compensated/reversible
phase
- Various compensatory mechanisms are activated
- Blood is redistributed to maintain perfusion to vital
organs

19. 2. Progressive phase
- If the underlying cause of shock is not corrected,
shocks passes into the progressive phase
- Widespread tissue hypoperfusion, hypoxia and
blood pools in the microcirculation
- Cardiac output worsens and there will be
widespread hypoxic damage to vital organs and
they begin to fail

20. 3. Irreversible phase
- If there is no intervention, shock enters into irreversible
stage
- Widespread cell injury further worsens shock
- Acute renal failure
- Death

21. Morphology
- Kidney: acute tubular necrosis(acute renal failure)
- Lungs: diffuse alveolar damage - acute respiratory
distress - “shock lung”
- Disseminated intravascular coagulation(DIC): widespread
deposition of micro-thrombi, especially in brain, heart,
lungs, kidney, adrenal glands and GI tract

22. Prognosis
- Hypovolemic shock: can survive with appropriate
management
- Septic shock, cardiogenic shock with massive MI:
poorer prognosis

23. References:
● Ramadas Nayak - Textbook of Pathology for Allied Health
Sciences
Questions:
salman.s.ansari92@gmail.com