Pathology for all mbbs and bs programs shock topic

1. Shock
Pre by ZAHID REHMAN
LECTURER IPMS(KMU)

2. LECTURE OBJECTIVE
 At the end of this lecture the student will be able to know
 Definition of shock
 Types of shock
 Causes of shock

3. Shock
 state characterized by systemic hypotension
 Occur due to diminished cardiac output or due to reduced
effective circulating blood volume.
 Results in impaired tissue perfusion and cellular hypoxia.
 Prolong shock can cause irreversible injury and can be fatal.

4. Definition
 Shock is a state in which diminished cardiac output or
reduced effective circulating blood volume impaired tissue
perfusion and leads to cellular hypoxia.
 Inadequate perfusion and oxygenation of cells leads to:
Cellular dysfunction and damage
Organ dysfunction and damage

5. Pathophysiology: of shock
 Tissue perfusion is determined by Mean Arterial
Pressure (MAP)
MAP = CO x SVR*o2 content in the blood
Heart rate Stroke Volume

6. Types of shock
 Most common type of shock are
 Cardiogenic shock
 Septic shock
 Hypovolemic shock
 Other types of shock are
 Neurogenic shock , anaphylactic shock and psychogenic
shock

7. Cardiogenic shock
Cardiogenic Shock
Myocardial Infarction with damage to heart muscle; heart
unable to pump effectively. Inadequate cardiac output. Body
cells do not receive enough oxygen.

8. Intrinsic causes of cardiogenic shock
Myocardial Injury or Obstruction to Flow
Arrhythmias
MI
Cardiomyopathies
Rupture of the heart ,ventricle or papillary muscles.

9. Cardiogenic Shock, extra cardiac
(Obstructive)
 Ball Valve thrombosis
Pulmonary Embolism
Cardiac Tamponade
Tension Pneumothorax
Dissecting aortic aneurysm

10. Pathophysiology of Cardiogenic Shock
 Heart fails to pump blood out
MAP = CO x SVR
HR Stroke Volume

11. Normal
MAP=CO*SVR Cardiogenic Shock
MAP = ↓CO x SVR
MAP = ↓CO x ↑ SVR
↓MAP = ↓↓CO x ↑ SVR

12. HYPOVOLUMIC SHOCK
Severe bleeding or loss of body fluid from trauma, burns,
surgery, or dehydration from severe nausea and vomiting.
Blood pressure decreases, thus blood flow is reduced to cells,
tissue, and organs
OR
Reduced circulating blood volume with secondary decreased
cardiac output

13. Non-hemorrhagic
Vomiting
Diarrhea
 pancreatitis
Burns
 environmental (dehydration)

14. Hemorrhagic
GI bleed
Trauma
Massive hemoptysis
AAA rupture
Ectopic pregnancy, post-partum bleeding

15. Hypovolemic Shock: Pathophysiology
 Heart pumps well, but not enough blood volume to pump
MAP = CO x SVR
HR x Stroke volume

16. Normal
MAP = CO x SVR
Hypovolemic
MAP = ↓CO x SVR
MAP = ↓CO x ↑ SVR
↓MAP = ↓↓CO x ↑ SVR

17. When the blood flow decrease the resistance of the blood vessel
increase to response the body constrict the blood vessel
cause vasoconstriction due to sympathatic tone of vessel.
Due to increase the resistance of vessel the blood flow squeeze
towards the heart, mostly happened in the venous drainage.
Sympathetic tone also act on the heart to increased the heart
rate.

18. Shock associated with systemic
inflammation
 Release of inflammatory mediators causes
 Arterial vasodilation
 Vascular leakage
 Venous pooling of blood
 All the these causes tissue hypo perfusion , cellular hypoxia ,
metabolic derangement and ultimately organ dysfunction or
organ failure and death.

19. Septic shock
An acute infection, usually systemic, that overwhelms the body
(toxic shock syndrome). Poisonous substances accumulate in
bloodstream and blood pressure decreases, impairing blood
flow to cells, tissues, and organs.

20.  Shock with severe sepsis characterize by hypotension.
 Septic shock can not be corrected by infusion fluid.
 Causes of septic shock:
 Immune reaction against the infection result in systemic
vasodilation , decrease vascular resistance and cause
peripheral pooling of blood which cause tissue hypo
perfusion

21.  Agents :
 Most common cause are gram positive bacteria
e.g. staphylococcus aurous , enterococci, strep pneumonia
Gram negative bacteria
Fungi
Protozoa

23.  Morphological changes:
 DIC cause
Micro thrombi in this condition thrombosis occur in brain , heart
and lungs.

24. Anaphylactic reaction

25. Anaphylactic Shock
 Results from reaction to substance to which patient is
hypersensitive or allergic (allergen extracts, bee sting,
medication, food). Outpouring of histamine results in dilation
of blood vessels throughout the body.

26. Pathophysiology
Heart pumps well, but there is peripheral vasodilation
due to loss of vessel tone
MAP = CO x SVR
HR x Stroke volume

27. Normal
MAP = CO x SVR
Anaphylactic
MAP = co x ↓ SVR
MAP = ↑cox ↓ SVR
↓MAP = ↑cox ↓↓ SVR

28. Neurogenic Shock
Injury or trauma to the nervous system (spinal cord,
brain). Nerve impulse to blood vessels impaired,
blood vessels remain dilated and blood pressure
decreases.

29. • higer injuries = worse paralysis
MPA= CO*SVR decrease

30. 6.Psychogenic Shock
 Shock caused by overwhelming emotional factors. Sudden
dilation of blood vessels results in fainting because of lack of
blood supply to the brain.

31. 7.Respiratory Shock
Trauma to the respiratory tract (trachea, lungs) that causes a
reduction of oxygen and carbon dioxide exchange. Body cells
cannot receive enough oxygen.

32. Signs
 decrease in blood pressure
 rapid, weak, or absent pulse
 irregular heart rate
 confusion
 rapid and shallow breathing
 anxiety
 decrease in urine

33.  chest pain
 nausea
 thirst and dry mouth
 low blood sugar
 fever (septic shock only)

34. Causes
 Anything that affects the flow of blood through the body can
cause shock. Some common causes of shock are:
 significant blood loss
 dehydration
 allergic reaction
 reduced blood pressure
 heart failure
 nerve damage
 blood infections

35. Treatment for Shock
 Hypovolemic shock is usually treated by blood transfusion.
 Shock caused by dehydration is treated with IV fluids.
 Shock caused by anaphylaxis is treated with epinephrine and
other drugs.
 Cardiogenic shock is treated by improving blood flow through
to the heart.