SHOCK , PATHOPHYSIOLOGY Prof.M.H.MUMTAZ.

1. SHOCK , PATHOPHYSIOLOGYProf.M.H.MUMTAZ. 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 Final Common Pathway!

5. 6 O2 GLUCOSE Aerobic Metabolism 6 CO2 6 H2O METABOLISM 36 ATP HEAT (417 kcal)

6. Anaerobic Metabolism 2 LACTIC ACID GLUCOSE METABOLISM 2 ATP HEAT (32 kcal)

7. Inadequate Energy Production Anaerobic Metabolism Lactic Acid Production Metabolic Failure Cell Death! Metabolic Acidosis Anaerobic? So What? Inadequate Cellular Oxygenation

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. Muscle Anatomy

12. Contraction: Sliding Filaments image from: http://www.accessexcellence.com/AB/GG/muscle_Contract.html

13. What Is Blood Pressure? BP = Cardiac Output X Systemic Vascular Resistance CO = Stroke Volume X Heart Rate

14. What Affects Blood Pressure? • ANS balance • Contractility • Preload • Starling’s law • Afterload

15. Autonomic Nervous System Review… Quiz Time! Yeah!

16. Jeopardy Controls vegetative functions,exits the CNS at high in the neck and low in the back. What is the parasympathetic nervous system?

17. Jeopardy The chief neurotransmitter of the sympathetic nervous system. What is Norepinephrine?

18. Jeopardy The ‘cutesy’ name for the parasympathetic nervous system. What is ‘Feed or Breed’?

19. Jeopardy Two types of parasympathetic receptors. What is nicotinic (NMJ) and muscarinic (organs)?

20. Jeopardy Two types classes of sympathetic receptors. What is alpha and beta?

21. Jeopardy The ‘cutesy name’ for the sympathetic nervous system. What is ‘fight or flight’?

22. Jeopardy Stimulation of this receptor causes an increase in peripheral vasoconstriction. What is alpha 1?

23. Jeopardy Stimulation of this receptor causes an increase in myocardial contractility. What is beta 1?

24. Jeopardy Stimulation of this receptor causes an increase in bronchodilation. What is beta 2?

25. Jeopardy Stimulation of this receptor causes a decrease in the sympathetic activation. What is alpha 2?

26. Jeopardy Two types of parasympathetic receptors. What is nicotinic (NMJ) and muscarinic (organs).

27.  peripheral vascular resistance… •  afterload… •  blood pressure. Changes in Afterload and Preload  •  Peripheral vasoconstriction…

28.  peripheral vascular resistance… •  afterload… •  blood pressure. Changes in Afterload and Preload   •  Peripheral vasodilation…

29.  preload… •  contractility (Starling’s Law)… •  blood pressure. •  cardiac output. Changes in Afterload and Preload  •  fluid volume…

30.  preload… •  contractility (Starling’s Law)… •  blood pressure. •  cardiac output. Changes in Afterload and Preload  •  fluid volume…

31. Fluid • Must have adequate amounts of hemoglobin • Must have adequate intravascular volume

32. Maintenance of Fluid Volume • Renin-Angiotensin-Aldosterone system. • Works through kidneys to regulate balance of Na+ and water.

33. Kidney (juxtaglomerular apparatus) Detected by Releases Via ACE (Angiotensin Converting Enzyme) Renin Converts Angiotensin II… Angiotensinogen Angiotensin I… Renin-Angiotensin-Aldosterone • Plasma volume &/Or  [Na+]

34.  vasoconstriction  PVR  thirst • ADH (anti-diuretic hormone) • Fluid volume  BP! Releases • Na+ reabsorption Adrenal cortex Aldosterone Renin-Angiotensin-Aldosterone Angiotensin II…

35. Hemostasis • The stoppage of bleeding. • Three methods • Vascular constriction • Platelet plug formation • Coagulation

36. Coagulation • Formation of blood clots • Prothrombin activator • Prothrombin  thrombin • Fibrinogen  fibrin • Clot retraction

37. Fibrinolysis • Plasminogen • Tissue plasminogen activator (tPA) • Plasmin

38. Disseminated Intravascular Coagulation “A systemic thrombohemorrhagic disorder … with evidence of: • Procoagulant activation • Fibrinolytic activation • Inhibitor consumption • End-organ failure” Bick, R.L. Seminars in Thrombosis and Hemostasis 1996

39. Pathophysiology of DIC • Uncontrolled acceleration of clotting cascade • Small vessel occlusion • Organ necrosis • Depletion of clotting factors • Activation of fibrinolysis • Ultimately severe systematic hemorrhage

40. Container • Vasculature is continuous, closed and pressurized system • Microcirculation responds to local tissue needs • Blood flow dependent on PVR

41. Fick Principle • Effective movement and utilization of O2 dependent on: • Adequate fio2 • Appropriate O2 diffusion into bloodstream • Adequate number of RBCs • Proper tissue perfusion • Efficient hemoglobin ‘loading’

42. Fick Principle • Perfusion = Arterial O2 Content - Venous O2 Content • Affected by: • Hemoglobin levels • circulation of RBCs • distance between alveoli and capillaries • pH and temperature

46. Onloading Oxygen in Lungs oxyhemeglobin pH 7.45 • Remember: • CO2  [H+] pH 7.4 Saturation •  pH shifts curve to left •  ‘onloading’ in lungs deoxyhemeglobin Pressure

47. Offloading Oxygen in Tissues oxyhemeglobin pH 7.4 • Remember: • CO2  [H+] pH 7.35 Saturation • pH shifts curve to right •  ‘offloading’ to tissues deoxyhemeglobin Pressure

48. 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

49. 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

50. O2 use Impaired cellular metabolism Anaerobic metabolism Stimulation of clotting cascade & inflammatory response Impaired glucose usage • ATP synthesis  Intracellular Na+ & water • Cellular edema  Vascular volume • Na+ Pump Function Cellular Response to Shock • Tissue perfusion