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ABCs of Shock

ABCs of Shock. Pediatric Critical Care Medicine Emory University Children’s Healthcare of Atlanta. Objectives. Review basic physiology of shock states in pediatrics Classification and recognition of clinical shock states Review initial management of shock. Definition. Shock?. Shock?.

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ABCs of Shock

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  1. ABCs of Shock Pediatric Critical Care Medicine Emory University Children’s Healthcare of Atlanta

  2. Objectives • Review basic physiology of shock states in pediatrics • Classification and recognition of clinical shock states • Review initial management of shock

  3. Definition

  4. Shock?

  5. Shock?

  6. Definition • Failure of delivery oxygen and substrates to meet the metabolic demands of the tissue beds SUPPLY < DEMAND Oxygen delivery < Oxygen Consumption DO2 < VO2 • Failure to remove metabolic end-products • Result of inadequate blood flow and/or oxygen delivery

  7. Definition • Common pathway • Failure to deliver substrates  conversion to anaerobic metabolism • Reversible if recognized early • Irreversible organ damage at the late stage • Progressive acidosis and eventually cell death • Early recognition is key

  8. Epidemiology • Incidence: not clear • Shock is not commonly listed as the diagnosis in ER visits • Estimated that more children die from sepsis than cancer each year • Common causes: hypovolemia, sepsis & trauma • Worldwide: diarrhea • Developed countries: trauma

  9. Pathophysiology • Children • Higher % body water • Higher resting metabolic rate • Higher insensible losses • Lower renal concentrating ability • Subtle signs/symptoms • Higher risk for organ hypo-perfusion

  10. Pathophysiology O2 supply < O2 demand O2 delivery < O2 consumption DO2 < VO2

  11. Oxygen delivery (DO2) • DO2 = CO x CaO2 • DO2 : oxygen delivery • CO : Cardiac output • CaO2: arterial oxygen content • CO = HR x SV • HR: heart rate • SV: stroke volume • CaO2 = HgB x SaO2 x 1.34 + (0.003 x PaO2) • Oxygen content = oxygen carried by HgB + dissolved oxygen

  12. Critical DO2: consumption depends on delivery Oxygen delivery (DO2)DO2= CO x CaO2

  13. Oxygen delivery DO2= COx CaO2

  14. Oxygen delivery DO2= COx CaO2 • CO = HR x SV • HR is independent • Neonates depend on HR (can’t increase SV) • SV depends on • Pre-load: volume of blood • After-load: resistance to contraction • Contractility: force

  15. Oxygen delivery DO2=CO x CaO2 • CaO2 = HgB x SaO2 x 1.34 + (0.003 x PaO2) • Normal circumstance: CaO2 is closely associated with SaO2 • Severe anemia or in the presence of abnormal HgB (i.e. CO poisoning) - CaO2 is strongly affected by PaO2

  16. Hypo-perfusion • Poor perfusion of a vital organs leads to organ dysfunction • Decreased urine output • Altered mental status • Elevated LFTs, bilirubin • Switches to anaerobic metabolism  Lactate • Activates inflammatory cascade • Activates neutrophils, releases cytokines • Increases adrenergic stress response • Increases lipolysis/glycogenolysis (also increases lactate) • Releases catecholamine and corticosteroid

  17. Classification of ShockStages vs. Types

  18. Stages of Shock • Compensated • Maintains end organ perfusion • BP is maintained usually by ↑ HR • Uncompensated • Decreases micro-vascular perfusion • Sign/symptoms of end organ dysfunction • Hypotensive • Irreversible • Progressive end-organ dysfunction • Cellular acidosis results in cell death

  19. Blood Pressure and Volume • BP drops quickly after reaching 50% blood loss • CO follows BP closely

  20. Systemic Inflammatory Response Syndrome (SIRS) • Widespread inflammation due to infection, trauma, burns, etc. • Criteria – requires 2 of the followings • Core temp >38.5˚C or <36˚C • Tachycardia (or bradycardia in infants) • Tachypnea • Elevated or depressed WBC or >10% bands

  21. Types of Shock • Hypovolemic • Distributive • Cardiogenic • Septic

  22. Types of Shock

  23. Hypovolemic Shock • Most common type in children • #1 cause of death worldwide • Hemorrhagic: developed countries – GI bleed, trauma (liver/spleen injuries, long bone fractures), intracranial hemorrhage • Non-hemorrhagic: vomiting/diarrhea, heat stroke, burns, DKA • Pathophysiology: • Loss of intravascular volume  ↓ PRELOAD

  24. Hypovolemic Shock • Clinical symptoms • Sunken fontanel/eyes • Dry mucous membrane • Poor skin turgor • Delayed capillary refill • Cool extremities • Tachycardia = compensated shock! • Normal BP until volume loss >30-40%

  25. Distributive Shock • Loss of SVR (AFTERLOAD) results in abnormal distribution of blood flow • Increased CO and HR • Often hyper dynamic contractility, bounding pulses, flash CR • Loss of vascular tone eventually leads to loss of PRELOAD • Blood volume pools in the periphery

  26. Distributive Shock • Anaphylaxis is IgE mediated hypersensitive response • Massive release of cytokines from activated mast cells • Associated with respiratory distress, angioedema, vascular tone collapse • Neurogenic: unusual and mostly transient • Follows acute CNS injury (brain or spinal cord) • Loss of sympathetic and autonomic tone • Unique presentation: hypotension with normal heart rate

  27. Distributive Shock VasodilationVenous pooling Decrease after-load Mal-distribution of regional blood flow

  28. Cardiogenic Shock • Impaired CONTRACTILITY (pump failure) • 3 categories • Cardiomyopathy • Arrhythmia • Obstruction

  29. Cardiogenic Shock • Cardiomyopathy • Infectious – post viral infection (coxsakie) • Infiltrative – storage disease • Ischemia – cardiac arrest or bypass • Sepsis – late stage

  30. Cardiogenic Shock • Arrhythmia • Ventricular fibrillation & pulseless ventricular tachycardia abolish cardiac output • Prolonged or recurrent SVT • Brady-arrhythmias or heart block seen in neonatal SLE

  31. Cardiogenic Shock • Obstructive • Physical obstruction – tension pneumothorax, tamponade, pulmonary embolus • Congenital - coartation of the aorta, hypoplastic left heart, critical aortic stenosis • Usually present in shock with closing of the ductus arteriosus

  32. Septic Shock

  33. Septic Shock • 20% presentation – classic warm shock • High CO, low SVR • 60% presentation – cold shock • Low CO, high SVR • Small % presentation with mixed pictures

  34. Septic Shock • Highest in infants (particularly in newborns) • Risks • Structural heard disease • Neutropenia • Neurodevelopmental disorders • Invasive devices

  35. Evaluation & Treatment

  36. Initial Assessment • Goals • Immediate identification of life-threatening conditions • Rapid recognition of circulatory compromise • Early classification of the type and cause of shock

  37. Initial Assessment • Airway • Mental status: can the patient maintain the airway • Breathing • ?impending respiratory failure • Circulation • Heart rate, pulses, blood pressure • Capillary refills - perfusion • Dextrose

  38. Treatment Increase O2 contents Increase cardiac output Increase blood pressure Early intubation Sedation Analgesia

  39. Surviving sepsis Campaign 2008

  40. PALS Shock Algorithm

  41. History & Physical Exam • Brief medical history • Preceding events, recent illness or trauma • PMH • Allergies & exposure • Focused physical examination • Neuro – mental status • CV – HR/perfusion/CR, ?gallop/murmur • Resp – crackles, wheezing • GI - ?HSM

  42. Early Goal-Directed Therapy • Goal – in the first 6 hours of presentation - improvement of indicators of perfusion and vital organ function • Physiologic targets • BP >5th percentile for age • Quality of central & peripheral pulses • Normal perfusion • Mental status • UOP > 1 ml/kg/hr

  43. Fluid Resuscitation • Isotonic crystalloids – availability • 20cc/kg  reassess (overload vs. third spacing) • Rapid infusion – 5 - 10 min • NO upper limit • Pressor if > 60ml/kg • May need up to 100-200 ml/kg during the first few hours

  44. Volume

  45. Treatment: Volume • Volume resuscitation  optimize preload • >60 ml/kg during 1st hr associated with increase survival • Titrate volume to improve CO, normal HR, BP; improve perfusion/cap refill; improve UOP, MS • Carcillo JA, Fields AI. Clinical practice parameters for hemodynamic support of pediatric and neonatal patients in septic shock. Crit. Care Med. 2002; 30:1365-1378

  46. Treatment: Volume • Retrospective review of 34 pts with septic shock & hypovolemia with 1st hr fluid resuscitation • Group 1: up to 20ml/kg • Group 2: 20-40ml/kg • Group 3: >40mg/kg • No different in rate of ARDS • Carcillo JA, Davis AL, Zaritsky A, Role of early fluid resuscitation in pediatric septic shock. JAMA. 1991; 266:1242-1245

  47. Treatment: Volume • Colloids – blood products • Trauma or DIC in septic shock • PRBC to help with oxygen carrying and delivery

  48. PALS Shock Algorithm

  49. Vasopressors

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