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- 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
- 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.
- 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.