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Pathology 301

Pathology 301. Awatif Jamal, MD, MSc, FRCPC, FIAC Consultant & Associate Professor Department of Pathology King Abdulaziz University Hospital. Hemodynamic Disorders Thrombosis & Shock. Shock. Shock. Shock or cardiovascular collapse. Shock constitutes systemic hypo perfusion due to

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Pathology 301

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  1. Pathology 301 • Awatif Jamal, MD, MSc, FRCPC, FIAC • Consultant & Associate Professor • Department of Pathology • King Abdulaziz University Hospital

  2. Hemodynamic Disorders Thrombosis & Shock • Shock Shock

  3. Shock or cardiovascular collapse Shock constitutes systemic hypo perfusiondue to reduction either in : --cardiac output --or in the effective circulating blood volume. It is the common final pathway for a number of potentially lethal events including ; severe hemorrhage Extensive trauma Severe burns Large myocardial infarction Massive pulmonary embolism Massive microbial sepsis.

  4. Shock or cardiovascular collapse The end results are: • 1.Hypotension, followed by • 2.Impaired Tissue Perfusion • 3.Cellular Hypoxia • 4. Hypoxic and metabolic effects of hypoperfusion causes initially reversible cell injury. • 5. Persistence of shock causes irreversible cell injury, even to death of patient.

  5. Shock • Shock or “cardiovascular collapse” could be grouped into three Main Categories: • Cardiogenic shock • Hypovolemic shock • Septic shock • Others: • Neurogenic Shock (spinal cord injury) • Anaphylactic Shock

  6. Cardiogenic Shock Results From Severe Myocardial Pump Failure Due to: Myocardial Infarction Ventricular Arrhythmia Extrinsic Compression (Cardiac Tamponade) Outflow Obstruction (Pulmonary Embolism)

  7. Hypovolemic Shock • Results From Loss of Blood or Plasma Volume: • Hemorrhage • Fluid loss from severe burns or trauma

  8. NEUROGENIC SHOCK • In case of spinal cord injury or anesthetic accident which can lead to; • Loss of vascular tone • And peripheral pooling of blood

  9. ANAPHYLACTIC SHOCK • Initiated by generalized Ig E-mediated hypersensitivity reaction associated with systemic vasodilatation and increased vascular permeability.

  10. Septic Shock Most common cause of death in ICU’s in the US • The incidence is increasing due to; • Improved life support for high-risk patients • Increased invasive procedures • Increasing number of immunocompromized cases as HIV infection, secondary to chemotherapy, and immunosuppression. • Caused by systemic microbial infection; most often by endotoxins-producing gram-negative bacilli infection (endotoxic shock) [in 70% of cases], but can also occur with gram-positive and fungal infections

  11. Pathogenesis Of Endotoxic [Septic] Shock Endotoxins are bacterial wall lipopolysaccharides (LPS) which consists of ; --a toxic fatty acid (lipid A) core and --a complex polysaccharide coat. LPS are released when the cell walls are degraded in an inflammatory response.

  12. Pathogenesis Of Endotoxic [Septic] Shock • Free LPS attaches to circulating LPS- binding proteins, • It will then bind to a receptor ( CD14) in macrophages , monocytes, and neutrophils leading to their activation and production of TNF, and IL-1. • Depending on the dose and number of macrophages that are activated ,the secondary effects of LPS release can cause severe pathologic changes including the fatal shock.

  13. Pathogenesis Of Septic Shock • High quantities of LPS • systemic vasodilatation (hypotension) • diminished cardiac contractility (low cardiac output) • endothelial injury and activation  leukocyte adhesion • activation of coagulation system ( Disseminated Intravascular Coagulopathy) • adult respiratory distress syndrome ( ARDS) • multiorgan system failure and death

  14. Shock Stages of Shock: Shock is a progressive disorder that evolves through 3 stages, and if uncorrected will lead to death. • Initial “Non-progressive stage”: • Reflex compensatory mechanism activation  maintain perfusion of vital organs through maintenance of cardiac output and blood pressure. • C/P; tachycardia, • peripheral vasoconstriction ,cold skin, pallor (although septic shock may be associated with inflammation and hotness)

  15. Stages of Shock • Irreversible stage: • Severe cellular and tissue injury  thus survival is not possible • Acute renal tubular necrosis • Adult respiratory distress syndrome ( ARDS ) • Bowel ischemia and release of its flora. • Disseminated Intravascular Coagulopathy • “Progressive stage: • tissue hypo perfusion with widespread hypoxia  circulatory & metabolic imbalance. • C/P: patient is confused • Reduced urine output.

  16. Disseminated Intravascular Coagulation (DIC) • Sudden widespread fibrin deposition in microcirculation • Rapid consumption of platelets and coagulation proteins (consumption coagulopathy) • Secondary massive fibrinolysis, all the little thrombi dissolve • Clotting disorder turns into a Bleeding Disaster

  17. THANK YOU

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