Shock In Children
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Shock In Children

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Shock In Children Shock In Children Presentation Transcript

  • SHOCK IN CHILDREN
  • Definition
    • Circulatory system failure to supply
    • oxygen and nutrients to meet cellular
    • metabolic demands
  • Other Definitions
    • Blood Pressure
      • BP = CO x SVR
    • Cardiac Output
      • CO = SV X HR
    • Vascular Tone (SVR)
      • Regulated by several mechanisms
  • Oxygen Delivery
    • DO 2 = CO x CaO 2 x 10
      • Remember: CO depends on HR, preload, afterload, and contractility
    • CaO 2 = Hgb x 1.34 x SaO 2 + (PaO 2 x 0.003)
      • Remember: hemoglobin carries more than 99% of oxygen in the blood under standard conditions
  • Hemodynamics Textbook of Pediatric Advanced Life Support, 1988
  • Defending the blood pressure
    • Neural Sympathetic
      • Baroreceptors
        • Carotid Body
        • Aortic Arch
      • Volume receptors
        • Right Atrium
        • Pulmonary vascular
      • Chemoreceptors
        • Aortic and carotid
        • Medullary
      • Cerebral ischemic response
    • Humoral
      • Adrenal medulla
        • Catecholamines
      • Hypothalamopituitary response
        • Adrenocorticotropic hormone
        • Vasopressin
      • Renin-angiotensin-aldosterone system
  • Cardiovascular function
    • Cardiac Output
      • Clinical Assessment
        • peripheral perfusion, temperature, capillary refill, urine output, mentation, acid-base status
      • CO = HR x SV
        • HR responds the quickest
        • SV is a function of three variables
          • preload, afterload, and myocardial contractility
        • A noncompliant heart cannot increase SV
  • Stroke Volume
    • Preload (LVEDV)
      • Reflects patient’s volume status
      • CVP or PCWP
      • Starling curve
    • Afterload
      • The resistance to ventricular ejection
      • Two variables:
        • vascular tone and transmural pressure
    • Myocardial Contractility (“squeeze”)
      • Many factors including coronary perfusion, baseline myocardial function, use of cardiotonic medications
  • Classification of Shock
      • COMPENSATED
        • blood flow is normal or increased and may be maldistributed; vital organ function is maintained
      • UNCOMPENSATED
        • microvascular perfusion is compromised; significant reductions in effective circulating volume
      • IRREVERSIBLE
        • inadequate perfusion of vital organs; irreparable damage; death cannot be prevented
  • Other Classifications
    • Hypovolemic or Hemorrhagic
    • Cardiogenic
    • Obstructive
    • Distributive
  • Cardiovascular Changes in Shock
    • Type Preload Afterload Contractility
    • Cardiogenic   
    • Hypovolemic   No change
    • Distributive   
    • Septic
      • early   
      • late   
  • Evaluation
    • Regardless of the cause: ABC’s
      • First assess airway patency, ventilation, then circulatory system
    • Respiratory Performance
      • Respiratory rate and pattern, work of breathing, oxygenation (color), level of alertness
    • Circulation
      • Heart rate, BP, perfusion, and pulses, liver size
      • CVP monitoring may be helpful
  • Evaluation
    • Early Signs of Shock
      • sinus tachycardia
      • delayed capillary refill
      • fussy, irritable
    • Late Signs of Shock
      • bradycardia
      • altered mental status (lethargy, coma)
      • hypotonia, decreased DTR’s
      • Cheyne-Stokes breathing
      • hypotension is a very late sign
      • Lower limit of SBP = 70 + (2 x age in years)
  • Cardiovascular Assessment
    • Heart Rate
      • Too high: 180 bpm for infants, 160 bpm for children >1year old
    • Blood Pressure
      • Lower limit of SBP = 70 + (2 x age in years)
    • Peripheral Pulses
      • Present/Absent
      • Strength (diminished, normal, bounding)
    • Skin Perfusion
      • Capillary refill time
      • Temperature
      • Color
      • Mottling
    • CNS Perfusion
      • Recognition of parents
      • Reaction to pain
      • Muscle tone
      • Pupil size
    • Renal Perfusion
      • UOP >1cc/kg/hr
  • Treatment
    • Airway management
      • Always provide supplemental oxygen
      • Endotracheal intubation and controlled ventilation is suggested if respiratory failure or airway compromise is likely
        • elective is safer and less difficult
        • decrease negative intrathoracic pressure
        • improved oxygenation and O 2 delivery and decreased O 2 consumption
        • can hyperventilate if necessary
  • Treatment
    • Circulation
      • Based on presumed etiology
      • Rapid restoration of intravascular volume
        • PIV-if unstable you have 60-90 seconds
        • I.O. if less than 4-6 years old
        • Central venous catheter
        • Use isotonic fluid: NS, LR, or 5% albumin
        • PRBC’s to replace blood loss or if still unstable after 60cc/kg of crystalloid
          • anemia is poorly tolerated in the stressed, hypoxic, hemodynamically unstable patient
  • Vasoactive/Cardiotonic Agents
    • Dopamine
      • 1-5 mcg/kg/min: dopaminergic
      • 5-15 mcg/kg/min: more beta-1
      • 10-20 mcg/kg/min: more alpha-1
      • may be useful in distributive shock
    • Dobutamine
      • 2.5-15 mcg/kg/min: mostly beta-1, some beta-2
      • may be useful in cardiogenic shock
    • Epinephrine
      • 0.05-0.1 mcg/kg/min: mostly beta-1, some beta-2
      • > 0.1 to 0.2 mcg/kg/min: alpha-1
  • Vasoactive/Cardiotonic Agents
    • Norepinephrine
      • 0.05-0.2mcg/kg/min: only alpha and beta-1
      • Use up to 1mcg/kg/min
    • Milrinone
      • 50mcg/kg load then 0.375-0.75mcg/kg/min: phosphodiesterase inhibitor; results in increased inotropy and peripheral vasodilation (greater effect on pulmonary vasculature)
    • Phenylephrine
      • 0.1-0.5mcg/kg/min: pure alpha
  • Hypovolemic
    • # 1 cause of death in children worldwide
    • Causes
        • Water Loss (diarrhea, vomiting with poor PO intake, diabetes, major burns)
        • Blood Loss (obvious trauma; occult bleeding from pelvic fractures, blunt abdominal trauma, “shaken baby”)
    • Low preload leads to decreased SV and decreased CO.
    • Compensation occurs with increased HR and SVR
  • Hypovolemic Shock
    • Mainstay of therapy is fluid
    • Goals
      • Restore intravascular volume
      • Correct metabolic acidosis
      • Treat the cause
    • Degree of dehydration often underestimated
      • Reassess perfusion, urine output, vital signs...
    • Isotonic crystalloid is always a good choice
      • 20 to 50 cc/kg rapidly if cardiac function is normal
      • NS can cause a hyperchloremic acidosis
  • Treatment
    • Solution Na+ Cl- K+ Ca++ Mg++ Buffer
    • NS 154 154 0 0 0 None
    • LR 130 109 4 3 0 Lactate
    • Plasmalyte 140 98 5 0 3 Acetate & Gluconate
    • Inotropic and vasoactive drugs are not a substitute for fluid, however...
      • Can have various combinations of hypovolemic and septic and cardiogenic shock
      • May need to treat poor vascular tone and/or poor cardiac function
  • Hemorrhagic Shock
    • Treatment is PRBCs or whole blood
      • Treat the cause if able (stop the bleeding)
      • Transfuse if significant blood loss is known or if patient unstable after 60cc/kg crystalloid
        • In an emergency can give group O PRBCs before cross matching is complete or type specific non-cross-matched blood products
  • Cardiogenic
    • Low CO and high systemic vascular resistance
    • Result of primary cardiac dysfunction:
        • A compensatory increase in SVR occurs to maintain vital organ function
        • Subsequent increase in LV afterload, LV work, and cardiac oxygen consumption
        • CO decreases and ultimately results in volume retention, pulmonary edema, and RV failure
  • Cardiogenic Shock Etiologies
    • Congenital heart disease
    • Arrhythmias
    • Ischemic heart disease
    • Myocarditis
    • Myocardial injury
    • Acute and chronic drug toxicity
    • Late septic shock
    • Infiltrative diseases
      • mucopolysaccharidoses
      • glycogen storage diseases
    • Thyrotoxicosis
    • Pheochromocytoma
  • Cardiogenic Shock
    • Initial clinical presentation can be identical to hypovolemic shock
    • Initial therapy is a fluid challenge
    • If no improvement or if worsens after giving volume, suspect cardiogenic shock
    • Usually need invasive monitoring, further evaluation, pharmacologic therapy
    • Balancing fluid therapy and inotropic support can be very difficult.
      • Call an intensivist and/or a cardiologist
  • Obstructive Shock
    • Low CO secondary to a physical obstruction to flow
    • Compensatory increased SVR
    • Causes:
      • Pericardial tamponade
      • Tension pneumothorax
      • Critical coarctation of the aorta
      • Aortic stenosis
      • Hypoplastic left heart syndrome
  • Obstructive Shock
    • Initial clinical presentation can be identical to hypovolemic shock
    • Initial therapy is a fluid challenge
    • Treat the cause
      • pericardial drain, chest tube, surgical intervention
      • if the patient is a neonate with a ductal dependent lesion then give PGE
    • Further evaluation, invasive monitoring, pharmacologic therapy, appropriate consults
  • Distributive Shock
    • High CO and low SVR (opposite of hypovolemic, cardiogenic, and obstructive)
    • Maldistribution of blood flow causing inadequate tissue perfusion
    • Due to release of endotoxin, vasoactive substances, complement cascade activation, and microcirculation thrombosis
    • Early septic shock is the most common form
  • Distributive Shock
    • Goal is to maintain intravascular volume and minimize increases in interstitial fluid (the primary problem is a decrease in SVR)
      • Use crystalloid initially
      • Additional fluid therapy should be based on lab studies
      • Can give up to 40cc/kg without monitoring CVP
      • Vasoactive/Cardiotonic agents often necessary
      • Treat the cause (i.e.. antimicrobial therapy)
  • Distributive Shock Etiologies
    • Anaphylaxis
    • Anaphylactoid reactions
    • Spinal cord injury/spinal shock
    • Head injury
    • Early sepsis
    • Drug intoxication
      • Barbiturates, Phenothiazines, Antihypertensives
  • Metabolic Issues Acid-Base
    • Metabolic acidosis develops secondary to tissue hypoperfusion
    • Profound acidosis depresses myocardial contractility and impairs the effectiveness of catecholamines
    • Tx: fluid administration and controlled ventilation
    • Buffer administration
      • Sodium Bicarbonate 1-2meq/kg or can calculate a 1/2 correction = 0.3 x weight (kg) x base deficit
      • hyperosmolarity, hypocalcemia, hypernatremia, left-ward shift of the oxyhemoglobin dissociation curve
  • Metabolic Issues Electrolytes
    • Electrolytes
      • Calcium is important for cardiac function and for the pressor effect of catecholamines
      • Hypoglycemia can lead to CNS damage and is needed for proper cardiovascular function
      • Check the BUN and creatinine to evaluate renal function
      • Hyperkalemia can occur from renal dysfunction and/or acidosis
  • Metabolic Issues Special Topics
      • Congenital adrenal hyperplasia
        • Infant presents in shock, usually in the second week of life, typically a boy, with metabolic acidosis, hyponatremia, hypoglycemia, and hyperkalemia
      • Hyperammonemia
        • mild elevations are common with shock
        • levels > 1000 are consistent with inborn errors of metabolism
        • consider Reye Syndrome, toxins, hepatic failure
  • Other Studies
    • Look for etiology of shock
    • Evaluate hemoglobin, hematocrit, and platelet count
      • Should be followed as these values may drop after fluid resuscitation
    • Shock from any etiology can lead to DIC and end organ damage
      • CBC, PT, INR, PTT, Fibrinogen, Factor V, Factor VIII, D-dimer, and/or FDPs
      • Check LFT’s, follow CNS and pulmonary status
  • Other Studies II
    • Think about inborn errors of metabolism
      • Lactate and pyruvate
      • Ammonium, LFTs
      • Plasma amino acids, urine organic acids
      • Urinalysis with reducing substances
      • Urine tox screen
  • Conclusion
    • Goal of therapy is identification, evaluation, and treatment of shock in its earliest stage
    • Initial priorities are for the ABC’s
    • Fluid resuscitation begins with 20cc/kg of crystalloid or 10cc/kg of colloid
    • Subsequent treatment depends on the etiology of shock and the patient’s hemodynamic condition
    • Successful resuscitation depends on early and judicious intervention