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    Undifferentiated Shock – Diagnosis and Treatment

    Cardinal Presentations / Presenting Problems, Critical Care / Resuscitation

    Last Reviewed on Feb 17, 2022
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    By Samantha Jang-Stewart,Kevin Choi


    • Shock is a state of acute cardiocirculatory failure resulting in end-organ hypoxia and dysfunction.
    • Promptly recognizing and treating shock is important as it is associated with high mortality
    • Shock has many etiologies and is the final common pathway of death.
    • Approach to undifferentiated shock requires simultaneous resuscitation and investigation.

    Table 1 Categories of shock

    Diagnostic Process

    Approach to undifferentiated shock

    1. Recognize shock.
    • No single clinical finding or investigation can rule in or rule out shock. Diagnosis is based on a combination of clinical findings.
    • Shock is commonly associated with hypotension, but it can also occur with normal blood pressure.
    • Shock red flags
      • Ill appearance.
      • Altered mental status.
      • HR > 100, MAP < 65, SBP < 90, shock index (SI) > 0.8.
      • RR > 20.
      • Urine output < 0.5 ml/kg/h.
      • Skin – cool peripheries, mottling, urticaria.
      • Lactate > 4 mM/L or arterial base deficit < -4mEq/L.
    1. Primary survey (ABCDE)
    • Airway: assess airway patency.
    • Breathing: assess oxygenation and ventilation.
      • Consider the need for intubation and mechanical ventilation. Minimize induction agents to avoid hemodynamic collapse.
    • Circulation: assess pulse, BP, telemetry, signs of obvious bleeding.
      • Obtain large bore peripheral IV access. Obtain intraosseous access if peripheral IV access is difficult. Do not delay resuscitation for central line access.
    • Disability: assess for level of consciousness and signs of spinal cord injury.
    • Exposure: assess skin for urticaria, angioedema (signs of anaphylaxis).
    • Rule out conditions requiring immediate intervention: tension pneumothorax, massive hemothorax, cardiac tamponade, MI, significant arrhythmias, massive PE, anaphylaxis, hypovolemia.
    1. Initiate empiric resuscitation unless the cause of shock is clear and is rapidly reversed.
    • Fluid resuscitation.
      • Fluid challenge with 300-500 ml of a crystalloid solution over 20-30 min. Repeat according to fluid responsiveness based on changes in BP, HR, urine output.
      • Be cautious with excessive fluid administration, especially if suspecting cardiogenic shock or massive PE.
      • Colloids like albumin are theoretically better intravascular volume expanders but there is no evidence of mortality benefit over crystalloids.
    • Consider vasoactive agents if hypotension persists (MAP <65) despite fluid resuscitation.
      • Typical first line agent is norepinephrine with initial dose of 0.2 mcg/kg/min. Norepinephrine can initially be given through peripheral IV until central line access is available.
      • Vasopressin and epinephrine infusions can be used as second-line agents for severe cases of shock.
    • Consider the use of inotropes if suspecting cardiogenic shock. Dobutamine is commonly used as a first line agent.
    • Start broad-spectrum antibiotics if suspecting sepsis. Early antibiotic therapy improves outcomes in sepsis.
    • Consider empiric corticosteroids for chronic steroid users or shock refractory to vasopressors and fluid resuscitation. Options include dexamethasone 6 mg IV or hydrocortisone 100 mg IV.
    • Sodium bicarbonate therapy for severe metabolic acidosis is commonly used but there is no evidence of mortality benefit.
    1. Secondary survey focused on determining the cause of shock.
    • History: trauma, infection, immunosuppression, corticosteroid use, exposure to allergen, chest pain, toxic ingestions.
    • Head to toe examination.
    • Point of care ultrasound (FAST, RUSH).
      • Recent systematic review suggests ultrasound measurement of IVC is not a reliable indicator of volume status.
    • Suggested initial investigations.
      • Blood tests: ABG, lactate, CBC, serum chemistry, LFT, troponin, BNP, coagulation studies.
      • ECG – ACS.
      • CXR – heart failure or pneumonia.
      • CT scan depending on working differential.
    • Consider placing arterial line and/or central line.
    1. Reassess indicators of adequate hemodynamic support.
    • MAP > 65 with clinical signs of adequate tissue perfusion (mental status, skin appearance, urine output).
    • Decreasing serial lactate measurements.

    6. Transition to ICU.

    Quality Of Evidence?


    Substantial evidence on the diagnosis and management of shock. Most clinical trials are specific to the ICU but of high quality.


    Related Information

    Reference List

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    2. Annane D, Siami S, Jaber S, Martin C, Elatrous S, Declère AD, Preiser JC, Outin H, Troché G, Charpentier C, Trouillet JL, Kimmoun A, Forceville X, Darmon M, Lesur O, Reignier J, Abroug F, Berger P, Clec’h C, Cousson J, Thibault L, Chevret S; CRISTAL Investigators. Effects of fluid resuscitation with colloids vs crystalloids on mortality in critically ill patients presenting with hypovolemic shock: the CRISTAL randomized trial. JAMA. 2013 Nov 6;310(17):1809-17. doi: 10.1001/jama.2013.280502.

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    4. Orso D, Paoli I, Piani T, Cilenti FL, Cristiani L, Guglielmo N. Accuracy of Ultrasonographic Measurements of Inferior Vena Cava to Determine Fluid Responsiveness: A Systematic Review and Meta-Analysis. J Intensive Care Med. 2020 Apr;35(4):354-363. doi: 10.1177/0885066617752308. Epub 2018 Jan 17. PMID: 29343170.

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