SHOCK

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SHOCK

• NGA B. PHAM, MD, FAAP
• CRITICAL CARE MEDICINE
• CHILDRENS HEALTHCARE OF ATLANTA
• EGLESTON
• 2006

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Objectives

• Review basic physiologic aspects of shock
• Define shock and its different categories
• Describe management of shock

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What is Shock?Pathophysiology of shock

• Oxygen
• Demand gt Supply

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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

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Determinants of Oxygen Delivery

• Oxygen
• Delivery Content x Cardiac output

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Determinants of Oxygen Delivery

• Oxygen content 1.34 (Hgb x SaO2) (PaO2 x
  0.003)
• SaO2 Oxygen saturation
• Hgb Hemoglobin concentration
• PaO2 partial pressure Oxygen in plasma
• To improve Oxygen content
• Increase Hemoglobin concentration
• Increase saturation

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Determinants of Oxygen Delivery

• Cardiac output
• C.O. Heart rate x stroke volume
• To improve Cardiac output
• Increase Heart rate
• Increase Stroke Volume
• Preload volume of blood in the ventricle
• Afterload resistance to contraction
• Contractility force applied

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Secondary Organ Dysfunction

• Respiratory failure
• Tachypnea
• Decreased compliance
• Pulm edema, pulm infiltrate, etc.
• Increased resistance
• Diaphragm fatigue
• Central vs peripheral
• Demand gtgt supply
• Inadequate O2 delivery

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Secondary Organ Dysfunction

• CNS altered mental status
• Renal insufficiency pre-renal
• Coagulation abnormalities DIC
• Hepatic/GI dysfunction bowel ischemia
• Endocrine Calcium, hypo-adrenalism, vasopressin

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Classification of Shock

• Hypovolemic Shock (1 cause world wide)
• Dehydration, hemorrhagic
• Cardiogenic Shock
• Pump failure, obstructive, L-R shunt
• Distributive Shock
• Neurogenic
• Anaphylaxis
• Septic Shock All of the above

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Classification of Shock

• Compensated
• Organ perfusion is maintained
• Uncompensated
• Circulatory failure with end organ dysfunction
• Irreverisble
• Irreparable loss of essential organs

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Mechanical Requirements for Adequate Tissue
Perfusion

• Fluid
• Pump
• Vessels
• Flow

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Hypovolemic Shock

• 1 cause of death world wide
• Gastroenteritis
• Hemorrhagic Trauma, GI bleed

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Diagnosis of Hypovolemic Shock

• Early
• Increase HR
• Decrease perfusion
• Normal BP, decrease pulse pressure
• Late
• Sign increase HR
• Sign decrease perfusion
• Decrease BP
• End organ dysfunction

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Pathophysiology of Hypovolemic Shock

• Decrease intravascular volume
• Compensation increase endogenous catecholamines
• Increase HR increase C.O., O2 delivery
• Increase SVR increase BP (esp diastolic)
• Compensation for lt15 dehydration

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Cardiogenic Shock

• Pump failure/malfunction
• (decreased contractility)

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Cardiogenic Shock

• Electrical Failure
• Arrhythmias
• Mechanical failure
• Cardiomyopathy
• Metabolic acidosis
• Anatomic
• Hypoxia/ischemia
• Obstruction

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Cardiogenic ShockSymptoms

• Tachycardia
• Tachypnea
• Respiratory distress
• Mental status change
• Cool extremities
• Poor perfusion
• Signs of dehydration

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Cardiogenic ShockObstruction of Flow

• Causes
• Pericardial tamponade
• Pulmonary embolism
• Pulmonary hypertension

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Cardiogenic ShockObstruction of Flow

• Cardiac tamponade
• Causes
• Pericarditis
• Post-traumatic
• Post-cardiac surgery
• Complication of central line placement
• Recognition
• Tachycardia
• Low C.O., narrow pulse pressure (inc. diastole)
• Inc. CVP, JVD
• PULSUS PARADOXUS (gt10mmHg)
• Muffled heart sounds (??rub)
• NO RALES

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Distributive Shock

• Abnormal vessel tone
• (decreased afterload)

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Distributive Shock

• Vasodilitation Venous Pooling
• Decreased Afterload
• Maldistribution of regional blood flow

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Distributive Shock

• Neurogenic or Anaphylactic Shock
• Diminished or absent sympathetic tone
• Reduce peripheral vascular tone
• Peripheral pooling of blood volume
• Inadequate venous return
• Decreased perfusion, acidosis, hypotension

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Septic Shock

• Terminology in Sepsis
• Infection response to micro organism
• Bacteremia bug in blood
• Systemic Inflammatory Response Syndrome (SIRS)
• Tgt38, lt36
• Increase HR
• Increase RR, paCO2lt32
• WBCgt12,000, lt4,000, gt10 bands

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Septic Shock

• Terminology in Sepsis
• Sepsis SIRS as response to a known infection
• Severe sepsis Sepsis organ dysfunction
• Septic Shock Sepsis inadequate oxygen
  delivery
• Multiple Organ Dysfunction Syndrome (MODS)
  organ dysfunction that requires intervention

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Septic Shock

• Components of Septic shock
• Decreased volume
• Decreased pump function
• Abnormal vessel tone

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Septic Shock

• Therapy for Caridovascular Support
• Preload Volume
• Contractility Inotropes
• Afterload Vasodilators

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Septic Shock

• Etiologies
• Inflammatory too much, too little
• Coagulation pathway DIC-bleeding, pro-coagulant,
  microthombosis
• Multiple organ system failure

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Recognition of Septic Shock

• Early warm shock similar to neurogenic shock
• Late Cold shock similar to cardiogenic shock

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Diagnosis of Septic Shock

• Establish presence of infection
• Inc. HR, normal or dec. BP perfusion
• Latic acidosis
• Muti-organ dysfunction

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Early vs Late Septic Shock
Early Late
Heart rate Tachycardia Tachycardia/ bradycardia
Blood pressure Normal decreased
Peripheral Perfusion Warm/cool Dec./inc. pulses Cool Dec. pulses
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Early vs Late Septic Shock
Early Late
End-organ skin Dec. cap refill Very dec. cap Refill
Brain Irritable, restless Lethargic, unresponsive
Kidneys Oliguria Oliguria, anuria
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Treatment Strategies in Shock
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Principles of Resuscitation

• Increase Oxygen Delivery\
• Increase Oxygen content
• Increase Cardiac output
• Increase blood pressure
• Decrease Demand
• Sedation/analgesia
• Intubation

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Initial Treatment in Shock

• Airway
• Supplemental oxygen, intubation
• Carefull with cardiovascular collapse post
  intubation due to positive thoracic pressure
  decrease venous return
• Breathing
• Circulation
• Intravenous access go early, go IO
• Volume expansion (40cc/kg NS, repeat prn)
• Carefull with cardiogenic shock (5cc/kg then
  reassess)
• Optimize cardiac function, oxygenation

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Restoration of CirculationVolume

• Fluids, fluids, fluids
• Crystalloids vs Colloids

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Restoration of CirculationVolume

• Crystalloids
• NS is the fluid of choice, availability
• Rapid redistribution out of intravascular space
  capillary leak

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Restoration of CirculationVolume

• Colloids albumin, blood
• Albumin
• Worsening of edema due to cap leak in early
  sepsis
• Blood
• Great volume expanders
• Side effects with massive transfusion gt1.5 blood
  volumes
• Risk of infection
• Dilutional thrombocytopenia and factors V VIII
• Calcium binding hemodynamic instability (citrate)

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Restoration of CirculationVolume Fluid Choices

• Based on
• Type of deficit
• Urgency of repletion
• Pathophysiology of shock

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Restoration of CirculationVolume Fluid Choices

• Crystalloids for initial resuscitation
• Colloids/PRBCs to replace blood loss

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Treatment of ShockCardiac Support

• Alpha Dopamine Beta
• Epinephrine
• Norepinephrine Dobutamine
• Neosynephrine

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Inotropes
Agent Site of Action Dose Mcg/kg/min Effects
Dopamine Dopaminergic Beta Alpha gt Beta 1-3 5-10 11-20 Renal vasodilation Inotrope/vasoconstriction Increase perip. Vasc. resistance
Dobutamine Beta 1 2 1-20 Inotrope Vasodilation
Epineprhine Beta gt alpha 0.05 1.0 Inotrope, vasoconstriction Tachycardia
Norepinephrine Alpha gt beta 0.05 1.0 Profound vasoconstriction inotrope
Nitroprusside Vasodilator (art gt venous) 0.5 1.0 Vasodilation
Milranone Phosphodiesterase inhibitor 0.5 0.75 Inotrope vasodilation
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New Therapies in Septic Shock

• Vasopressin
• Steroids
• Activated protein C (Xigris) in Septic Shock

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New Therapies in Septic ShockVasopressin

• Unclear mechanism of action
• Bridging vascular instability in high exogenous
  catecholamines requirement septic shock,
  therefore decrease side effects of toxic dosage
  of catecholamines
• Also shows greater blood flow diversion from
  non-vital to vital organs

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New Therapies in Septic ShockVasopressin

• Dosage 0.01 0.04U/min up to 0.08U/min

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New Therapies in Septic ShockSteroids

• Hypo-adrenalism abnormal hypothalamus-pituitary-a
  drenal axis
• At risk of adrenal insufficiency in the
  presence of catecholamine requirement
• Fluid refractory shock
• Normal BP, cold shock
• Low BP, cold shock
• Dosage stress dose
• Hydrocortisone 150 mg/m2 ivp

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New Therapies in Septic ShockSteroids

• Glucocorticoid function immune response
• Fall in circulating lymphocytes
• Inhibits neutrophils migration to the
  inflammatory sites
• Inhibits macrophages secretion
• Promotes eosinophilic apoptosis
• Modulates cytokines production

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New Therapies in Septic ShockSteroids

• Glucocorticoid function Cardiovascular
• Modulate vascular reactivity to angiotensin II
  and to catecholamines -Not fully understood
  mechanism
• Modulate vascular permeability and production of
  NO and other vasodilator factor
• INCREASE IN BLOOD PRESSURE

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New Therapies in Septic ShockSteroids

• Glucocorticoid production in stress
• Maintain homeostasis
• Normalize vascular reactivity
• Modulate inflammatory response

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New Therapies in Septic ShockActivated
Protein C (Xigris)

• Recombinant Human Activated Protein C
• Prevent DIC cascade with antithrombotic activity
  by inhibiting factors Va VIIIa
• May exerts anti-inflammatory effects by
  inhibiting TNF and by blocking leukocytes
  adhesions
• Side effects
• Bleeding
• Pediatric trial terminated early (03/04) due to
  no benefit to known risk of bleeding