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CHAPTER 10

CHAPTER 10. SHOCK. What is Shock?. 1)Reduction of blood perfusion to tissues microcirculation. 2)Dysfunction of organs. 3)Disturbance of metabolism. What are causes and types of shock. 1)Hypovolemic shock

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CHAPTER 10

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  1. CHAPTER 10 SHOCK

  2. What is Shock? • 1)Reduction of blood perfusion to tissues microcirculation. • 2)Dysfunction of organs. • 3)Disturbance of metabolism.

  3. What are causes andtypes of shock • 1)Hypovolemic shock • Loss of plasmaburns • Loss of whole bloodhemorrage • Loss of other body fluiddiarrhea • 2)Cardiogenic shock 注意：此点有误， • Anaphylectic reaction 必改。 • Neurologic inhibition

  4. 3)Vasogenic shock • Anaphylectic reaction • Neurologic inhibition • 4)Septic shock • Gram-negative bacteria infection • Gram-positive bacteria infection

  5. Characteristics of hypodynamic shock: Vasoconstriction Peripheral resistance  Cardiac output  Cold skin Characteristics of hyperdynamic shock: Vasodilation Peripheral resistance  Cardiac output  Warm skin There are other 2 kinds of classification of shock: 1.Hemodynamic classification

  6. 2. classification of shock by severity • StageI • Early reversible shock • Compensatory mechanism • dominating

  7. 2. classification of shock by severity Stage II Late reversible shock Compensatory mechanism exahausted

  8. 2. classification of shock by severity Stage III Refractory shock Disseminated Intravascular Coagulation initiated

  9. Pathogenesis of Shock The part consists of three key points: 1.Starting Factors of Shock 2.Stages of Shock and Changes of Microcirculation 3.Mechanisms of Shock Vascular-Bed Volume Cardiac Output Blood Volume

  10. 1.Starting Factors of Shock (1)Reduction of blood volumeHemorrhage, Dehydration, Burn (2)Decrease of cardicoutput Myocardial infarction (3)Increase of vascular-bed volume Anaphylactic reaction 2.Stages of Shock and Changes of Microcirulation

  11. Causes of shock Effective blood volume  Sympathetic nerve (+) CA Release  Vasoconstriction (Arterioles and venous constriction) blood flow in microcirculation  Ischemic anoxia of tissues Harmful Effects ( 1)Stage of Vasoconstriction(Stage of Ischemic Anoxia)

  12. causes of shock Effective blood volume  Sympathetic nerve (+) CA Release  Vasoconstriction Self-infusion Self-blood transfusion Blood flow redistribution Conservation of Na+ &H2O Increased functions of heart Protective Effects

  13. ( 2)Stage of Vasodilation(Stage of Stagnant Anoxia)AnoxiaAcidosisEndotoxinshemorheology changesBlood stasis

  14. ( 3)Stage of Vasofailure(Stage of DIC)Blood stasisEndothelium damagecoagulation cascade initiationthrombus formation and MOF

  15. 3.Mechanisms of Shock (1)Neurogenic Mechanisms Sympathetic stimulation Constriction Rapid heart rate of arterioles and Strengthening and venules Constriction of heart

  16. (2)Cellular Mechanisms Endotoxin Complement Split products Activation of Macrophages and Polymorphonuclear Leukocytes Release Lysosomal enzyme Oxy-free redicals IL-1 TNF Cells and Tissues Injury

  17. Catecholamines Noradrenaline and Adrenaline RAA System Renin-Angiotension-Aldosterone Vasopressin Histamine and Serotonin Kinins Neuropeptides Activated Complement Tumor Necrosis Factor Oxygen Free Radicals Prostaglandins and Leukotrienes (3)Humoral Mechanisms

  18. In brief, Roles that humoral factors play in development of shock are as follows: Effects on tension of vessel Effects on permeability of vessel Direct harmful effects on cells

  19. Effects of Shock on Vital Organs • 1.Shock-Lung Syndrome • CA & Hypoxia • disturbance of pulmolary circulation • lung edema Hemorrhage microthrombi • Adult Respiratory Distress • Syndrome(ARDS).

  20. 2.Shock Kidney • Sympathetic stimulation & Secretion of CA  Arteriolar constriction  renal ischemia and hypoxia  tubule necrosis and decrease of glomerular Filtration rate Renal Failure

  21. 3. Effects of Shock on Liver 3. Effects of Shock on Liver • Ischemia , hypoxia and toxic substances liver dysfunction  GTP and metabolic diturbance  hyperglycemia (early) and hypoglycemia (late) and blood amino acids  and so on.

  22. 4.Effects of Shock on Brain • In early stage, due to blood flow redistribution and autoregulatory mechanism, functions of brain still are normal. • Inlatestage, functions of brain are disturbed by cytotoxic edema, nerosis of brain cells resulting from harmful effects of OFR, Kinins and PGs, ect. • Clinically Restless, Lassitude and Coma are manifested.

  23. 5. Effects of Shock on Heart • In early stage, due to blood flow redistribution and autoregulatory vasodilation, performance of heart still is normal. • Inlatestage, functions of heart are disturbed by imbalance between availability and consumption of oxygen, acidosis, hyperkalemia,MDF and DIC in myocardium. • Clinically heart failure are manifested.

  24. 6.Multiple Organ Failue(MOF) • MOF is a comprehensive outcome of dysfunctions of the above organs in shock. • Cell damage is a fundamental cause of MOF, many harmful factors can induce cell damage.

  25. Characteristicsof Various Types of Shock 1.Hypovolemic shock Common causes:Hemorrhage, Burn, Dehydration etc. A key link of pathogenesis: Inadequate circulating blood volume Main mechanism: Sympathetic nervous system activation

  26. 2.Septic shock Common causes: Serious systemic infection ofbacteria,fungi,viruses,parasites,particularly gram-negative bacteremia • Main mechanism: • The above organisms→Monocytes and macrophages→cytokines(TNF,IL1)→cell damage,specially impairment of cellular uptake and/or utilization of O2

  27. Two types of septic shock • ＊Hyperdynamic type-warm shock • High cardiac output • Low vessel resistance • Flushed and warm skin • Mechanism:Histamine and Kinins induced-vasodila-tion • ＊Hypodynamictype-cold shock • Low cardiac output • High vessel resistance • Cold and wet skin • Mechanism: endotoxin, • Stagnant Microcircula-tion, • Sympathetic stimulation, • Vasoconstriction

  28. 3.Cardiogenic shock Common causes: • Myocardial infarction etc. • Main mechanism: • decrease of cardiac output 4.Anaphylactic shock Common causes: Hypersensitivity to some substances(antigens) such as penicillin, fish, shrimp etc.

  29. Main mechanism: • Massive releaseof mediators • such as histamine→dilationof arterioles and venules,and increase of capillary permeability→imbalancebetween volume of vessel bed and blood volume(the former﹥the latter) →shock

  30. 5.Neurogenic shock • Common causes: • Severe pain,spinal cord injury,etc. • Main mechanism: • Lack of vasomotor tone→dilationof peripheral vessel→decrease of peripheral • resistance→inadepuate returnof blood to heart→decreaseof cardiac output→shock

  31. Principle of Treatment of Shock 1.Elimination of initiating causes of shock For example, anti-infection, stop bleeding, anti-anaphylactic reaction. 2.Restoration of blood volume Intravenous administration of normal saline, glucose solution, blood, plasma and so on.

  32. 3.Application of vasoactive drugsAccording to different stages and types of shock, administer different agents. For example, in early stage, use dilating vessel agents, , use constricting vessel agents for anaphylactic shock and so on. 4.Improvement of cardiac function Cardiac tonic such as digitalis and digoxin improves functions of heart. 5.Treatment of complications e.g.acidosis, hypoxia, DIC etc.

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