Shock

1. Shock Stephanie N. Sudikoff, MD Pediatric Critical Care Yale School of Medicine

2. Learning Objectives Understand the pathophysiology of shock Understand the principles of treatment of shock Examine septic shock as one example

3. �The reason you get up in the morning is to deliver oxygen to the cells.� Mark Mercurio, MD

5. Oxygen Consumption vs. Delivery Oxygen consumption (DEMAND) VO2 = CO x (CaO2-CvO2) Oxygen delivery (SUPPLY) DO2 = CO x CaO2

7. What are PRELOAD and AFTERLOAD?

8. Preload PreloadLV = (EDPLV)(EDrLV)/2tLV where, LV = left ventricle ED = end diastole Represents all the factors that contribute to passive ventricular wall stress at the end of diastole

10. Venous return and CO

11. Factors affecting venous return Decrease in intravascular volume Increase in venous capacitance Increase in right atrial pressure Increase in venous resistance

12. Afterload AfterloadLV = (SPLV)(SrLV)/2tLV where, LV = left ventricle S = systole Represents all the factors that contribute to total myocardial wall stress during systolic ejection

14. Myocardial contractility

15. Myocardial contractility

16. Heart rate HR ? CO At high HR, diastolic filling is impaired Atrial contraction accounts for up to 30% of Stroke Volume

17. SHOCK

19. Classification of Shock

20. Systemic response to low perfusion

21. Systemic response to low perfusion Increase CO Increase preload Aldosterone Na reabsorption Interstitial fluid reabsorption ADH secretion Venoconstriction

22. Systemic response to low perfusion Increase CO Increase contractility Sympathetics Increase afterload Vasoconstriction Increase HR Sympathetics

23. Systemic response to low perfusion Increase CO Increase contractility Sympathetics Increase HR Sympathetics Increase SVR Vasoconstriction Increase blood volume

24. Local response to low perfusion Increase O2ER Opening of previously closed capillaries Increased surface area for diffusion Shortened diffusion distance Increased transit time

25. Physical Signs of low CO

26. Objective monitors Systemic perfusion base deficit lactate

27. Objective monitors Systemic perfusion ABG lactate CO PA catheter Arterio-venous oxygen difference Preload CVP Echo Myocardial contractility Echo Afterload PA catheter Invasive or noninvasive BP HR EKG CaO2 Hb ABG

28. TREATMENT OF SHOCK

29. Goals of therapy Treat underlying cause

30. Reduction of demands for CO Treat hyperthermia aggressively

31. Reduction of demands for CO Treat hyperthermia Reduce work of breathing As much as 20% of CO goes to respiratory muscles

32. PPV and CO Advantages Decreases work of breathing Improves acidosis Decreases PVR Decreases LV afterload Improves oxygenation

33. Reduction of demands for CO Treat hyperthermia Reduce work of breathing Sedation Seizure control Paralysis

35. Increase supply:Restoration of perfusion Preload Fluid resuscitation Colloids vs. crystalloids

36. Increase supply:Restoration of perfusion Preload Fluid resuscitation Colloids vs. crystalloids Myocardial contractility Inotropic support ECMO Other mechanical support

37. Increase supply:Restoration of perfusion Preload Fluid resuscitation Colloids vs. crystalloids Myocardial contractility Inotropic support ECMO Other mechanical support Afterload Vasopressors Vasodilators

38. Increase supply:Restoration of perfusion Preload Fluid resuscitation Colloids vs. crystalloids Myocardial contractility Inotropic support ECMO Other mechanical support Afterload Vasopressors Vasodilators HR Anti-arrhythmics Pacer

39. Increase supply:Restoration of perfusion Preload Fluid resuscitation Colloids vs. crystalloids Myocardial contractility Inotropic support ECMO Other mechanical support Afterload Vasopressors Vasodilators HR Anti-arrhythmics Pacer Beta-blockers? CaO2 Blood transfusion Oxygen support

40. SEPTIC SHOCK

43. Types of septic shock Cold shock ? CO, ? SVR (60% pediatric) Narrow pulse pressure, thready pulses, delayed capillary refill

44. Phases of septic shock Warm shock (�early�) ? CO, ? SVR ? CO, ? SVR Wide pulse pressure, bounding pulses, brisk capillary refill Cold shock (�late�) ? CO, ? SVR Narrow pulse pressure, weak pulses, delayed capillary refill

46. Early recognition!

47. Early recognition!

49. Increase preload Aggressive fluid resuscitation

50. Increase preload Aggressive fluid resuscitation Usually requires 40-60 mL/kg but can be as much as 200 mL/kg 20 mL/kg IV push titrated to clinical monitors

51. Monitor improvement in CO Cardiac output Heart rate Urine output Capillary refill Level of consciousness Blood pressure NOT reliable endpoint

52. Increase preload Aggressive fluid resuscitation with crystalloids or colloids Usually requires 40-60 mL/kg but can be as much as 200 mL/kg 20 mL/kg IV push titrated to clinical monitors Maintain hemoglobin within normal for age (=10 g/dL)

53. Antibiotic therapy IV antibiotics within 1 hr of recognition of severe sepsis Cultures before antibiotics Cover appropriate pathogens Penetrate presumed source of infection

55. Improve myocardial contractility and titrate afterload

59. Cold Shock, Adequate BP:Decrease afterload

61. Adequacy of resuscitation Capillary refill < 2 sec Adequate pulses Warm limbs Normal mental status Urine output > 1 mL/kg/hr Adequate blood pressure Improved base deficit Decreased lactate ScvO2 > 70%

62. Early shock reversal improves outcome

63. SUMMARY

65. Goals of therapy Treat underlying cause

67. Special thanks to Vince Faustino, MD for use of his slides