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Shock

Shock. Stephanie N. Sudikoff, MD Pediatric Critical Care Yale School of Medicine. Learning Objectives. Understand the pathophysiology of shock Understand the principles of treatment of shock Examine septic shock as one example.

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Shock

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  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

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

  5. What are PRELOAD and AFTERLOAD?

  6. 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

  7. Venous return and CO

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

  9. 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

  10. Myocardial contractility

  11. Myocardial contractility

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

  13. SHOCK

  14. Shock

  15. Classification of Shock

  16. Systemic response to low perfusion

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

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

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

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

  21. Physical Signs of low CO

  22. Objective monitors • Systemic perfusion • base deficit • lactate

  23. 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

  24. TREATMENT OF SHOCK

  25. Goals of therapy • Treat underlying cause

  26. Reduction of demands for CO • Treat hyperthermia aggressively

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

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

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

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

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

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

  33. 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

  34. 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

  35. SEPTIC SHOCK

  36. Types of septic shock • Cold shock • ↓ CO, ↑ SVR (60% pediatric) • Narrow pulse pressure, thready pulses, delayed capillary refill

  37. 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

  38. Early recognition!

  39. Early recognition!

  40. Increase preload • Aggressive fluid resuscitation

  41. 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

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