Undifferentiated shock

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Undifferentiated HypotensionAlgorithm[1]

Check/manage the following in order:

Algorithm for the Evaluation of Hypotension(By Dr. Ravi Morchi)
  • Pulse (assess based on patient'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

Shock

Evaluation

Shock index (SI)[2]

SI = HR / SBP

  • Used when HR and SBP do not predict severity of hypovolemia in early stages
  • May be used as secondary triage tool in mass casualty incidents[3]
  • 0.5-0.7 is normal
  • >0.70-0.75 for occult shock or requirement of life-saving intervention

Management

  • Treat underlying type

Vasopressors

Pressor Initial Dose Max Dose Cardiac Effect BP Effect Arrhythmias Special Notes
Dobutamine 2.5 mcg/kg/min 10-40 mcg/kg/min mainly inotrope (ß1) alpha effect minimal Some HR(ß1) increase. Also Increase SA and AV node fx Debut Research 1979[4] Isoproterenol has most Β2 vasodilatory and Β1 HR effects
Dopamine 2 mcg/kg/min 20-50 mcg/kg/min β1 and NorEpi release α effects if > 20mcg/kg/min Arrhythmogenic from β1 effects More adverse events when used in shock compared to Norepi[5]
Epinepherine 0.1-1 mcg/kg/min
Norepinephrine 8-12 mcg/min 30 mcg/min β1 direct effect β1 and α1,2 effects Less arrhythmias than Dopamine[5] Increases MAP, coronary perfusion pressure, little β2 effects.
Milrinone 50 mcg/kg x 10 min 0.375-75 mcg/kg/min Direct influx of Ca2+ channels Smooth muscle vasodilator PDE Inhibitor which increases Ca2+ uptake by sarcolemma. No venodilatory activity
Phenylephrine 100-180 mcg/min then 40-60 mcg/min 0.4-9 mcg/kg/min Alpha agonist Long half life
Vasopressin Fixed Dose 0.4 U/min unknown increases via ADH peptide should not be titrated due to ischemic effects
Methylene blue[6] IV bolus 2 mg/kg over 15 min 1-2 mg/kg/hour Possible increased inotropy, cardiac use of ATP Inhibits NO mediated peripheral vasodilation Don't use in G6PD deficiency, ARDS, pulmonary hypertension
Medication IV Dose (mcg/kg/min) Concentration
Norepinephrine (Levophed) 0.1-2 mcg/kg/min 8mg in 500mL D5W
Dopamine 2-20 mcg/kg/min 400mg in 250 D5W
Dobutamine 2-20 mcg/kg/min 250mg in 250 mg D5W
Epinephrine 0.1-1 mcg/kg/min 1mg in 250 D5W

See Also

External Links

References

  1. ↑ Morchi R. Diagnosis Deconstructed: Solving Hypotensionin 30 Seconds. Emergency Medicine News. 2015.
  2. ↑ Levitan, Richard M. Fundamentals of Airway Management. 3rd ed. Irving, TX: Emergency Medicine Residents' Association, 2015.
  3. ↑ Vassallo J et al. Usefulness of the Shock Index as a secondary triage tool. J R Army Med Corps. 2015 Mar;161(1):53-7.
  4. ↑ Edmund H. Sonnenblick, M.D., William H. Frishman, M.D., and Thierry H. LeJemtel, M.D. Dobutamine: A New Synthetic Cardioactive Sympathetic Amine
  5. ↑ 5.0 5.1 De Backer Daniel et al. Comparison of Dopamine and Norepinephrine in the Treatment of Shock. NEJM 363(9). 779-789
  6. ↑ Pasin L et al. Methylene blue as a vasopressor: a meta-analysis of randomised trials. Crit Care Resusc. 2013 Mar;15(1):42-8.

Video

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