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

18. 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