Undifferentiated shock

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Undifferentiated Hypotension Algorithm

Check/manage the following in order:

  • Pulse (assess based on pt's age)
    • Too slow or too fast (to the point where CO is affected)?
      • If so, HR is likely primary etiology of hypotension
      • Pace or cardiovert
  • Volume Status
    • What is the LV end-diastolic volume?
      • Approximated by the IVC diameter or CVP
      • If low:
        • Assess for blood loss versus fluid loss
          • FAST for intra-abdominal bleed
          • US for ruptured AAA
          • Guaiac for GI bleed
          • CXR for hemothorax
        • Treat with IVF and/or pRBC depending on cause
  • Contractility
    • Is the myocardium severely depressed in its contractile function (cardiogenic shock)?
    • Is forward flow occurring?
      • Assess for valvular dysfunction (MR, AR)
      • Assess for obstruction (PE, tamponade)
  • Systemic Vascular Resistance
    • Pathologic vasodilation (decreased SVR) suggested by:
      • Warm extremities
      • Bounding pulse
    • Treated based on likely etiology of distributive shock (see below)

Differential Diagnosis


      • Classes of Hemorrhagic Shock
Blood Loss (mL) < 750 750-1000 1500-2000 >2000
Blood Loss (%) < 15 15-30 30-40 >40
Pulse rate (per min) <100 100-120 120-140 >140
Blood Pressure Normal Normal Decreased Decreased
Pulse Pressure (mmHg) Normal or Increased Decreased Decreased Decreased
Respiratory Rate (per min) 14-20 20-30 30-40 >35
Urine Output (mL/hr) >30 20-30 15-May Negligble
Mental Status Slightly Anxious Mildly Anxious Anxious, Confused Confused, Lethargic

See Also


  • Tintinalli
  • Morchi, Undifferentiated Hypotension and Shock, All LA Conference, 05/06/2010