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Shock

Shock. Jose Emmanuel M Palo, MD Internal Medicine/Critical Care Medicine. In critical illness, heart and lung must be considered as one organ system.

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Shock

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  1. Shock • Jose Emmanuel M Palo, MD • Internal Medicine/Critical Care Medicine

  2. In critical illness, heart and lung must be considered as one organ system. Adapted from Weibel ER: The Pathway for Oxygen: Structure and Function in the Mammalian Respiratory System. Cambridge, MA, Harvard University Press, 1984

  3. Shock • clinical syndrome of organ dysfunction due to cellular hypoxia from hypoperfusion

  4. Definitions • unrelated to “emotional shock” or the acute stress reaction

  5. Microvascular/ endothelial dysfunction Cellular Death Cellular injury Inflammatory mediators Hypoperfusion

  6. Multiple organ failure Death Cellular Death

  7. Determinants of Effective Tissue Perfusion • Cardiovascular Performance • Cardiac Function • Venous Return • Vascular Performance • Oxygen Transport • Cardiopulmonary level • Cellular level • Microvascular Function • Cellular Energy Metabolism

  8. Cardiovascular Function In humans, most critical organ perfusion is auto-regulated at MAP between 60-100 mmHg

  9. Cardiovascular Function Perfusion pressure ~ MAP

  10. SV x HR Preload • SNS and PNS balance • catecholamine levels/responsiveness • ACTH and cortisol • R-A-A • Vasopressin • prostacycline • Nitric Oxide • Adenosine • Drugs Afterload Contractility MAP = CO x SVR

  11. Oxygen Transport DO2 = 1.39 x CO x Hb x saO2 amount of oxygen leaving the heart per unit time

  12. Oxygen Transport VO2 = 1.39 x CO x Hb x (saO2-svO2) amount of oxygen being consumed per unit time

  13. Critical Delivery Threshold Physiologic Oxygen Supply Dependency Lactic Acidosis VO2 DO2 Mizock BA. Crit Care Med. 1992;20:80-93.

  14. Compensation VO2 = 1.39 x CO x Hb x (saO2-svO2) Arterial Desaturation

  15. Compensation VO2 = 1.39 x CO x Hb x (saO2-svO2) Anemia

  16. Compensation VO2 = 1.39 x CO x Hb x (saO2-svO2) Decreased CO

  17. Association Segment Oxygen Unloading

  18. Dissociation Segment Oxygen Unloading

  19. Oxygen Unloading

  20. Shock Types • Hypovolemic • Distributive • Cardiogenic • Obstructive • afterload • preload

  21. Hypovolemic Shock • decreased effective blood volume • decreased end-diastolic filling pressures • trauma, diarrheal illness • relative hypovolemic state in septic shock • volume is key

  22. Stages of Hypovolemic Shock

  23. Distributive Shock • decreased SVR due to loss of vasomotor control • frequently, need volume to unmask a distributive shock state • sepsis, anaphylaxis, anaphylactoid reactions, neurogenic shock, hypoadrenalism

  24. Distributive Shock • Anaphylactoid shock • ionic contrast media • protamine • opiates • polysaccharide volume expanders (dextran, hydroxyethyl starch) • muscle relaxants • anesthetics • Anaphylactic shock • insect envenomations • antibiotics (beta-lactams, vancomycin, sulfonamides) • heterologous serum (anti-toxin, anti-sera) • blood transfusion • immunoglobulins (esp IgA deficient) • Egg-based vaccines • latex

  25. Cardiogenic Shock • loss of cardiac pump function (intrinsic) • due to myocardial damage, loss of contractility • Special: valvular dysfunction • characterized by elevations of both diastolic volumes and pressures

  26. Extra-Cardiac Obstructive • due to obstruction of flow in the cardiovascular circuit • preload obstruction: cardiac tamponade, constrictive pericarditis, other intrathoracic processes • afterload obstruction: pulmonary embolism

  27. Hemodynamics of Shock Types • CO SVR PWP EDV • Hypovolemic • Distributive • Cardiogenic • Obstructive • afterload • preload

  28. Management Principles • frequently reversible in early stages • early recognition and emergent intervention are key • clinical signs and symptoms may be due to the primary shock state, compensatory mechanisms or end-organ effects

  29. Clinical Signs • Primary diagnosis - tachycardia, tachypnea, oliguria, encephalopathy (confusion), peripheral hypoperfusion (mottled, poor capillary refill vs. hyperemic and warm), hypotension • Differential DX: • JVP - hypovolemic vs. cardiogenic • Left S3, S4, new murmurs - cardiogenic • Right heart failure - PE, tamponade • Pulsus paradoxus, Kussmaul’s sign - tamponade • Fever, rigors, infection focus - septic

  30. Pulmo Artery Proximal (CVP) CO Thermistor Distal (PCWP) Sup Vena Cava Balloon port R Atrium R Ventricle The Swan-Ganz Catheter

  31. Diagnosis and Evaluation Invasive Monitoring • Arterial pressure catheter • CVP monitoring • Pulmonary artery catheter (+/- RVEF, oximetry) • MVO2 • DO2 and VO2 2 2

  32. Static and dynamic volume assessment • CVP • PCWP • Straight leg raising • Intrathoracic fluid index • Pulse pressure variability • Pre-ejection period variability • Pulse contour analysis

  33. PEEP Advanced Concepts: PPVar SV RAP

  34. Advanced Concepts: Straight Leg Raising Michard, 2008

  35. Advanced Concepts: Microvascular Function

  36. Advanced Concepts:Cellular Energetics

  37. A Clinical Approach to Shock Diagnosis and Management Initial Therapeutic Steps • Admit to ICU • Venous access (1 or 2 wide-bore catheters) • Central venous catheter • Arterial catheter • ECG monitoring • Pulse oximetry • Hemodynamic support (MAP < 60 mmHg) • Fluid challenge • Vasopressors for severe shock unresponsive to fluids

  38. A Clinical Approach to Shock Diagnosis and Management When Diagnosis Remains Undefined orInitial Management Fails • Pulmonary Artery Catheterization • Cardiac output • Oxygen delivery • Filling pressures • Echocardiography • Pericardial fluid • Cardiac function • Valve or shunt abnormalities

  39. A Clinical Approach to Shock Diagnosis and Management Immediate Goals in Shock Hemodynamic support MAP > 60mmHg PAOP = 12 - 18 mmHg Cardiac Index > 2.2 L/min/m2Maintain oxygen delivery Hemoglobin > 9 g/dL Arterial saturation > 92% Supplemental oxygen/mechanical ventilationReversal of oxygen dysfunction Decreasing lactate (< 2.2 mM/L) Maintain urine output Reverse encephalopathy Improving renal, liver fxn tests MAP = mean arterial pressure; PAOP = pulmonary artery occlusion pressure.

  40. SV x HR Preload • SNS and PNS balance • catecholamine levels/responsiveness • ACTH and cortisol • R-A-A • Vasopressin • prostacycline • Nitric Oxide • Adenosine • Drugs Afterload Contractility MAP = CO x SVR

  41. Case #1 • 90/M inpatient for cholecystitis, treated now for 11 days with antibiotics and fluid • Pacemaker 2 yrs ago for symptomatic bradycardia • PAC placed for peri-operative management • BP 189/86 PAWP 23 (6-12) HR 80 • CO 3 L/min (4-8) SVR 6600 (700-1300) • lactate 5 mmol/L (<2.2)

  42. Case #2 • 50/M brought to ER unresponsive, arrested and had ACLS/CPR for 12 minutes • Comatose now and on norepinephrine • Urine output 0 • BP 55/40 HR 45 PACW 8 (6-12) RA 0 (2-6) • CO 3.6 (4-8) SVR 1000 (700-1300) • lactate 12 mmol/L (<2.2) • )

  43. Case #3 • 59/M 2 days after STEMI, not on mechanical ventilator • BP 55/40 HR 110 RR 26 • PA 35/18 CVP 18 • PPV 8%

  44. End(points) • shock is common and life-threatening • differentiating diagnoses frequently requires invasive procedures • management is time dependent • use therapy with the highest physiologic benefit at the lowest physiologic cost

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