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Shock in the Pediatric Patient: or Oxygen Don’t Go Where the Blood Won’t Flow!

Shock in the Pediatric Patient: or Oxygen Don’t Go Where the Blood Won’t Flow!. James D. Fortenberry MD FAAP, FCCM Medical Director, PICU Division of Critical Care Medicine Children’s Healthcare of Atlanta. Objectives. Define shock and its different categories

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Shock in the Pediatric Patient: or Oxygen Don’t Go Where the Blood Won’t Flow!

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  1. Shock in the Pediatric Patient:orOxygen Don’t Go Where the Blood Won’t Flow! James D. Fortenberry MD FAAP, FCCM Medical Director, PICU Division of Critical Care Medicine Children’s Healthcare of Atlanta

  2. Objectives • Define shock and its different categories • Review basic physiologic aspects of shock • Describe management of shock including: • oxygen supply and demand • fluid resuscitation • crystalloid vs. colloid controversy • vasopressor support

  3. Definition of Shock • Uncontrolled blood or fluid loss • Blood pressure less than 5th percentile for age • Altered mental status, low urine output, poor capillary refill • None of the above

  4. Definition of Shock An acute complex pathophysiologic state of circulatory dysfunction which results in a failure of the organism to deliver sufficient amounts of oxygen and other nutrients to satisfy the requirements of tissue beds

  5. SUPPLY < DEMAND

  6. Definition of Shock • Inadequate tissue perfusion to meet tissue demands • Usually result of inadequate blood flow and/or oxygen delivery • Shock is not a blood pressure diagnosis!!

  7. Characteristics of Shock • End organ dysfunction: • reduced urine output • altered mental status • poor peripheral perfusion • Metabolic dysfunction: • acidosis • altered metabolic demands

  8. Essentials of Life • Gas exchange capability of lungs • Hemoglobin • Oxygen content • Cardiac output • Tissues to utilize substrate

  9. Arterial Oxygen Content 100 mm Hg PaO2 100 mmHg Partial Pressure SaO2 97% Oxygen Saturation + Hgb 15 gm/100 mL Hemoglobin + O2 in plasma O2 bound to Hgb

  10. Oxygen Delivery DO2=Cardiac Output x 1.34 (Hgb x SaO2) + Pa02 x 0.003 O2O2O2O2O2O2 Oxygen Express O2O2O2O2O2O2 Ca02

  11. Cardiac Output The volume of blood ejected by the heart in one minute 4 - 8 liters / minute

  12. Cardiac OutputC.O.=Heart Rate x Stroke Volume • Heart rate • Stroke volume: • Preload- volume of blood in ventricle • Afterload- resistance to contraction • Contractility- force applied

  13. Cardiac OutputC.O.=Mean arterial pressure (MAP) - CVP/SVR • To improve CO: • MAP • CVP • SVR

  14. Preload Afterload Contractility x Heart Rate Stroke Volume Cardiac Output O2 Content Resistance x x O2 Delivery Arterial Blood Pressure

  15. Hypovolemic dehydration,burns, hemorrhage Distributive septic, anaphylactic, spinal Cardiogenic myocarditis,dysrhythmia Obstructive tamponade,pneumothorax Compensated organ perfusion is maintained Uncompensated Circulatory failure with end organ dysfunction Irreversible Irreparable loss of essential organs Classification of Shock

  16. Mechanical Requirements for Adequate Tissue Perfusion • Fluid • Pump • Vessels • Flow

  17. Hypovolemic Shock: Inadequate Fluid Volume (decreased preload)

  18. Hypovolemic Shock:Causes • Fluid depletion • internal • external • Hemorrhage • internal • external

  19. Cardiogenic Shock: Pump Malfunction (decreased contractility)

  20. Cardiogenic Shock:Causes Electrical Failure • Mechanical Failure • Cardiomyopathy • metabolic • anatomic • hypoxia/ischemia

  21. Distributive Shock Abnormal Vessel Tone (decreased afterload)

  22. Distributive Shock Vasodilation Venous Pooling Decreased Preload Maldistribution of regional blood flow

  23. Distributive Shock: Causes • Sepsis • Anaphylaxis • Neurogenesis (spinal) • Drug intoxication (TCA, calcium, Channel blocker)

  24. Septic Shock Decreased Pump Function Decreased Volume Abnormal Vessel Tone

  25. Cardiac OutputC.O.=Heart Rate x Stroke Volume • Heart rate • Stroke volume: • Preload- volume of blood in ventricle • Afterload- resistance to contraction • Contractility- force applied

  26. Clinical Assessment • Heart rate • Peripheral circulation • capillary refill • pulses • extremity temperature • Pulmonary • End organ perfusion • brain • kidney

  27. Improving Stroke Volume:Therapy for Cardiovascular Support Preload Volume Inotropes Contractility Vasodilators Afterload

  28. Septic Shock Early (“Warm”) Decreased peripheral vascular resistance Increased cardiac output Late (“Cold”) Increased peripheral vascular resistance Decreased cardiac output

  29. Assessment of Circulation

  30. Heart Rate and Perfusion Pressure (MAP-CVP) Parameters by Age

  31. Assessment of Circulation

  32. OBSTRUCTIVE SHOCK OBSTRUCTED FLOW

  33. Obstructive Shock:Causes • Pericardial tamponade • Pulmonary embolism • Pulmonary hypertension

  34. Hemodynamic Assessment of Shock

  35. O2 content Cardiac output Blood pressure Goals of Resuscitation • Overall goal: • increase O2 delivery • decrease demand Treatment Sedation/analgesia

  36. Principles of Management • A: Airway • patent upper airway • B: Breathing • adequate ventilation and oxygenation • C: Circulation • optimize • cardiac function • oxygenation

  37. Act quickly,Think slowly. Greek Proverb

  38. Airway Management • Patients in shock have: • O2 delivery • progressive respiratory fatigue/failure • energy shunted from vital organs • afterload

  39. Airway Management • Early intubation provides: • O2 delivery and content • controlled ventilation which: • reduces metabolic demand • allows C.O. to vital organs

  40. Therapy Vagolysis Heart Rate  Chromotropy

  41. Fluid Choices Colloid Crystalloid Less Filling Tastes Great !

  42. CrystalloidsHypotonic Fluids (D5 1/4 NS) • No role in resuscitation • Maintenance fluids only

  43. Fluids, Fluids, Fluids • Key to most resuscitative efforts • Give generously and reassess

  44. CrystalloidsIsotonic Fluids • Intravascular volume expansion • Hauser: • crystalloids rapidly redistribute • Lethal animal model • NS = good resuscitative fluid • 4x blood volume to restore hemodynamics

  45. CrystalloidsIsotonic Fluids • 2 trauma studies • crystalloids = colloids but: • 4x amount • longer time to resuscitation

  46. CrystalloidsComplications • Under-resuscitation • renal failure • Over-resuscitation • pulmonary edema • peripheral edema

  47. CrystalloidsSummary • Crystalloids less effective than equal volume of colloids • Preferred when 1o deficit is water and/or electrolytes • Good in initial resuscitation to restore extracellular volume • Hypertonic solutions however, may act as plasma volume expanders

  48. Oncotic pressure (tendency to pull unit) Hydrostatic pressure (tendency to drive unit) Fluid Transport Capillary

  49. ColloidsAlbumin • Hepatic production • MW = 69,000 • 80% of COP • Serum t1/2: 18 hours endogenous 16 hoursexogenous

  50. ColloidsHydroxyethyl Starch (Hespan) • Synthetic • Derived from corn starch • Average MW = 69,000 • Stable, nonantigenic • Used for volume expansion • Renal excretion • t 1/2 2-67 hours • 90% gone in 42 days

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