Shock

Shock

Updated: 08/08/2022

© Jun Wang, MD, PhD

General features

• Cell/tissue hypoxia
• Due to circulatory failure
• Life threatening
• Reversible at early stage only
• Need to initiate therapy immediately while rapidly identify underlying etiology
• Treat underlying etiology
  

Stages

• Compensation: Perfusion of vital organs maintained
• Decompensation: Hypoperfusion and lactic acidosis
• Irreversible: Permanent cell/tissue damage, organ failure, usually leads to death

Classification

• Distributive: Relative hypovolemia due to pathological redistribution of intravascular volume, usually resulted from excessive vasodilation
  

• Systemic inflammatory response syndrome
• Septic shock
• Neurogenic shock
• Anaphylactic shock
• Drug and toxin-induced shock
• Endocrine shock

• Cardiogenic: Cardiac malfunctioning associated critical reduction of pumping capacity

• Cardiomyopathic
• Arrhythmic
• Mechanical

• Hypovolemic: Absolute hypovolemia due to loss of intravascular volume, usually acute

• Hemorrhagic
• Non-hemorrhagic

• Obstructive: Reduced cardiac pumping capacity due to obstruction of large vessels or heart

• Pulmonary vascular
• Mechanical

• Combined

Key pathogenesis

• Reduced oxygen delivery
• Inadequate oxygen utilization
• Increased oxygen consumption
• Mixed

Pathophysiology

Clinical presentations

• Hypotension
• Tachycarcia
• Tachypnia
• Cool clammy skin
• Change of mental status
• Oliguria

Ancillary exam findings

• Laboratory tests
  
• Metabolic acidosis
• Hyperlactatemia
• Impaired renal/liver function
• Etiology associated findings (CBC, coagulation, etc)
• Radiologic findings (depending on underlying causes)
• Chest: pneumonia, ARDS, widened mediastinum, etc
• Abdomen: intestinal obstruction, etc
• Head: trauma, hemorrhage, etc
• EKG
• Cardiac ischemia/infarct
• Arrhythmia
• Pulmonary embolism, etc

Diagnostic approaches

• Always suspected in patients with hypotension, hyperlactatemia and tachycardia
• Based on clinical and laboratory findings

Diagnosis

• Diagnosed based on clinical evaluation and lab results
• Evidences of hypoperfusion
  

• Change of mental status 
• Oliguria 
• Peripheral cyanosis

• Signs of compensatory mechanisms: Tachycardia, tachypnea, hypotension, etc
• Laboratory findings 
• Elevated blood lactate 
• Reduced PaCO₂

Initial management approaches

• Assess airway, breathing and circulation
• Lifesaving intervention if needed
• Etiology identification based on history, PE, ancillary tests
• Hemodynamic support

Practice questions

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