ZSFG AM Report Pearls 6/19/2017: SHOCK – Differentiating Etiology and Treatment of Cardiogenic Shock

Thanks to Chloe Ciccariello for presenting a case of afib with RVR found to have cardiogenic shock and new onset heart failure.

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Top Pearls:

  • When working up new Afib, work up should include considering your “T’s and E’s.” T = Thyroid studies, Troponin. E = EKG and ECHO.
  • ScVO2 (central venous oxygen saturation) is an oxygen SATURATION (not a PaO2) and can be used to differentiate cardiogenic shock from distributive shock. It is measured from a blood draw from a central catheter (often in the SVC), and it is a surrogate for SVO2 (mixed venous oxygen saturation).
  • Norepinephrine can be used as a vasopressor in cardiogenic shock for rapid, initial circulatory support especially if shock is not completely differentiated (See reference below).

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“SHOCK”

Diagnosis:

  • Hypotension (although can be mild) = typically SBP <90mmHg, MAP <70mmHg with tachycardia
  • Tissue Hypoperfusion (think 3 organ systems)
    • Skin – cold, clammy, cyanotic (low-flow state, i.e. cardiogenic) or warm, diaphoretic (vasodilation, i.e. sepsis)
    • Kidneys – low urine output, i.e. less than 0.5cc/kg/hr or elevated Cr
    • Brain – altered mental status
  • Elevated lactate – a sign of abnormal cellular oxygen metabolism

Differential:

Type of Shock Preload Afterload (SVR) Cardiac Output
Cardiogenic Low High Low
Distributive Low Low High (but can get low)
Hypovolemic Low High Low
Obstructive High or Low Low Low

Tips on Differentiating:

  • Warm extremities (septic, distributive) vs. cold extremities (cardiogenic, obstructive, hypovolemic)
  • ScVO2 (central venous oxygen saturation) = Low (low cardiac output), High (high cardiac output)
  • Volume Exam – (edema, elevated JVP to point to elevated R-sided cardiac pressures)
  • Limited U/S Exam (Volume – IVC, JVP, cardiac function)

 

Brief Discussion of Pressors in Cardiogenic Shock:

  • A question was raised about whether Norephinephrine can be used in cardiogenic shock. A 2010 trial compared norepi to dopamine, but it did not have a comparison group to inodilators (dobutamine and milrinone) in the study which are also used in cardiogenic shock.
  • Some authors would advocate that an inopressor (norepi, epi, dopamine (high dose)) would be indicated for circulatory support when a patient’s MAPs are very low and you are worried about the vasodilatory effect of inodilators.
  • In a trial of 1679 patients with circulatory shock from VARYING etiologies, who were randomly assigned to initial therapy with either dopamine or norepinephrine, there was a trend toward a higher rater of death at 28 days with dopamine and there were significantly more arrhythmias, predominantly atrial fibrillation. No difference in the treatment effect based on shock type, including the 280 patients with cardiogenic shock.

 

References:

  • De Backer et al. (2010). Comparison of dopamine and norepinephrine in the treatment of shock. NEJM 363(9): 779.
  • Vincent JL and De Backer D. (2013). Circulatory Shock. NEJM 369: 1725-1734.

Evernote link: https://www.evernote.com/shard/s509/sh/c8fc9051-e2ef-4df4-b2f9-871259ae56bd/476852550f394db4e8afe9afb628a0da

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