1	General Principles of Pathophysiology Energy Metabolism Perfusion Shock
2	Topics Define shock in terms of cellular function Review the requirements for adequate cellular perfusion (Fick principle) Review the mechanisms for starling’s law Preload vs. afterload Muscle contraction
3	Topics Continued Discuss the mechanisms for oxygen transport oxyhemoglobin dissociation curve Define the stages of shock Describe different causes of shock Define multiple organ dysfunction syndrome
4	Shock Defined Inadequate tissue perfusion Anaerobic metabolism
5	Aerobic Metabolism
6	Anaerobic Metabolism
7	Anaerobic? So What?
8	Homeostasis is maintenance of balance Requires proper functioning systems Cardiovascular Respiratory Renal
9	Physiology of Perfusion Dependant on 3 components of circulatory system Pump Fluid Container
10	Factors Affecting The Pump Preload Contractile force Frank-starling mechanism Afterload
11	What Is Blood Pressure? BP = Cardiac Output X Systemic Vascular Resistance
12	What Affects Blood Pressure? ANS balance Contractility Preload Starling’s law Afterload
13	Changes in Afterload and Preload Ý Peripheral vasoconstriction…
14	Changes in Afterload and Preload Ý Peripheral vasodilation…
15	Changes in Afterload and Preload Ý fluid volume…
16	Changes in Afterload and Preload ß fluid volume…
17	Hemostasis The stoppage of bleeding. Three methods Vascular constriction Platelet plug formation Coagulation
18	Coagulation Formation of blood clots Prothrombin activator Prothrombin Þ thrombin Fibrinogen Þ fibrin Clot retraction
19	Disseminated Intravascular Coagulation “A systemic thrombohemorrhagic disorder … with evidence of: Procoagulant activation Fibrinolytic activation Inhibitor consumption End-organ failure”
20	Pathophysiology of DIC Uncontrolled acceleration of clotting cascade Small vessel occlusion Organ necrosis Depletion of clotting factors Activation of fibrinolysis Ultimately severe systematic hemorrhage
21	Container Vasculature is continuous, closed and pressurized system Microcirculation responds to local tissue needs Blood flow dependent on PVR
22	Fick Principle Effective movement and utilization of O₂dependent on: Adequate fio₂ Appropriate O₂ diffusion into bloodstream Adequate number of RBCs Proper tissue perfusion Efficient hemoglobin ‘loading’
23	Fick Principle Perfusion = Arterial O₂ Content - Venous O₂ Content Affected by: Hemoglobin levels circulation of RBCs distance between alveoli and capillaries pH and temperature
24	Causes of Inadequate Perfusion Inadequate pump Inadequate preload Poor contractility Excessive afterload Inadequate heart rate Inadequate fluid volume Hypovolemia Inadequate container Excessive dilation Inadequate systematic vascular resistance
25	Responses to Shock Normal compensation includes: Progressive vasoconstriction Increased blood flow to major organs Increased cardiac output Increased respiratory rate and volume Decreased urine output
26	Cellular Response to Shock
27	Stages of Shock Compensated Uncompensated Irreversible
28	Compensated Shock Defense mechanisms are successful in maintaining perfusion Presentation Tachycardia Decreased skin perfusion Altered mental status
29	Uncompenstated Shock Defense mechanisms begin to fail Presentation Hypotension Prolonged Cap refill Marked increase in heart rate Rapid, thready pulse Agitation, restlessness, confusion
30	Irreversible Shock Complete failure of compensatory mechanisms Death even in presence of resuscitation
31	Types of Shock Hypovolemic Cardiogenic Neurogenic Anaphylactic Septic
32	Hypovolemic Shock “Fluid failure” Decreased intravascular volume Causes? “Third spacing”
33	Anaphylactic Shock “Container failure” Massive & systemic allergic reaction Large release of histamine Increases membrane permeability & vasodilation
34	Septic Shock “Container failure” Systemic infection
35	Multiple Organ Dysfunction System Progressive dysfunction of two or more organ systems Caused by uncontrolled inflammatory response to injury or illness Typically sepsis
36	References New York Presbyterian hospital hypertension center: Http://pc101186.Med.Cornell.edu/htchome/htbk/Htbkindex.htm Biographics Gallery: http://www.accessexcellence.com/AB/GG/#Anchor-Building-11481 RAS (Renin-Angiotensin-Aldosterone System): http://www.science.mcmaster.ca/Biology/4S03/RAS.HTM A graduate student’s hypertension page: http://www.teaching-biomed.man.ac.uk/student_projects/2000/mnpm6ven/default.htm