SHOCK,Pathophysiology,Introduction,what is shock?,Comatose?,Section I Overview,Introduction,Drop in BP？,Section I Overview,Case analysis,Chief complaint： Male, 45 years of age, severe laceration of the left leg in a car accident. Physical Examination： Appears pale and indifferent but with clear consciousness. Multiple soft tissue contusion. Left inguinal briefly covered, but with large amount of exudation. BP 105/85mmHg, HR 96/min. Sonogram indicates rupture of the spleen with an estimated 600ml of blood accumulation in the abdomen.,Section I Overview,Case analysis,Treatment： A laceration wound of 7cm in the left inguinal. Partial separation of the femoral artery and vein with a ruptured spleen. Vascular prosthesis and splenectomy were conducted. 400ml of blood transfusion during operation. 5Glucose solution I.V. after surgery. 2h post-surgery BP 80/50mmHg. Epinephrine and dopamine are given I.V., but BP remains low (85/60mmHg). Clammy skin and anuria. BP drops to 70/40mmHg the next morning. I.V. epinephrine with no effect. Patient goes into coma with B.P. at 7:30. Weak respiration and heart beat. Pronounced dead at 7:50.,Section I Overview,Questions:,1、This patient has a normal BP upon admission. Why does his BP drop dramatically after the surgery to repair injured vessels?,2、Why do the vasoconstrictors fail to restore BP?,3、How would you modify the treatment strategy for this patient?,Section I Overview,The term was originated from Greek. Its initial meaning was:,In the 1730s, this term was re-coined by a French doctor to describe,Shock,A pathological process caused by trauma,A violent collision or a heavy blow to the head,Section I Overview,Understanding shock: a progressive history,From the use of vasoconstrictor (restoration of BP) to the use of vasodilator,Understanding shock: a progressive history,microcirculation,Acute circulatory failure,3,Microcirculation disturbance the effects of pro-inflammatory mediators and anti-inflammatory mediators,Shock,Reduction of ECBV Inadequate perfusion of vital organs Cellular metabolism disturbance Dysfunction of organs,The pathogenesis of shock is complex, involving:,Shock is a general pathologic process, characterized by:,Including:,Section I Overview,Shock syndrome,Classic clinical presentation of shock:,Shock,peripheral vasoconstriction,severely diminished CO inadequate blood flow to the brain and kidneys,respiratory compensation for metabolic acidosis,pale and cold clammy skin,hyperventilation,oliguria,dulled sensorium ranging from agitation to stupor or coma,tachycardia with a thready pulse,hypotension with a narrowed pulse pressure,Section I Overview,Section II,Etiology and Classification of Shock,Hypovolemic shock,Section II,(1) Based on causes,1) Loss of blood or fluid Blood loss Hemorrhagic shock Fluid loss Dehydration shock Burn Burn shock 2) Trauma Traumic shock 3) Infection Infectious (endotoxic, septic) shock 4) Anaphylaxis Anaphylactic shock 5) Acute heart failure Cardiogenic shock 6) Strong stimulation on nerve system Neurogenic shock,Perfect perfusion,(2) Based on pathogenesis,Sufficient,blood volume,heart pump function,Normal function,Vascular bed volume,3 major determinants of effective perfusion :,Section II,Normal vasoconstriction and vasodilation,Any one of these determinants may influence the efficiency of perfusion,Effective circulatory blood volume,Referred to as the volume of blood circulating through the cardiovascular system per unit time, excluding blood stored in liver, spleen, and lymphatic sinusoid, or retained in capillary network.,Determining factors： sufficient overall blood volume sufficient cardiac output normal peripheral vasoactivity,Section II,hypovolemic shock,Loss of blood Loss of fluid burn,ECBV Insufficient venous return Cardiac output BP ,Negative feedback of pressure sensor SN excitation Constriction of peripheral vessels Tissue perfusion,Dilation of visceral microvessels due to inflammation or allergy, which results in blood stasis and decrease of ECBV,vasogenic shock,Myocardiogenic：myocardial infarct, septal heart disease,cardiogenic shock,Non-myocardiogenic: Acute Cardiac Tamponade, pneumothorax, PAH,Loss of blood and fluid,burn,trauma,infection,allergy,Strong stimulation of SN nerve (e.g., pain),hypovolemic,vasogenic,cardiogenic,Major cardiovascular pathologies,Major Determinants for Effective Perfusion,Normal,Sufficient,Blood volume,Shock type,Initial changes,Section II,Three types of shock (based on different initiating factors),Decrease,Hypovolemic shock,Adequate,Vascular bed volume,Increase,Vasogenic shock,Heart pump function,Cardiogenic shock,Disturbance,Clinical examples,Hemorrhage Burns or trauma,MI, CHF Arrhythmias,Anaphylaxis Sepsis,Vasogenic=maldistributive,Pathogenesis of Shock,the Microcirculatory Disturbance Theory,Section III,blood flow rather than blood pressure,stimulatio