Digital PharmD

Informatics in Pharmacy

shock

Pressors and Ionotropes

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Drug NameReceptor affectedHRBPCOUses
Norepinephrineα, β1↔↑↑↑↔ or ↑cardiogenic shock
Epinephrineα, β1, β2↑↑↑↑↑↑↑↑↑cardiogenic shock  and anaphylaxis
epi activates everything)
Dopamineα, β1, dopaminergic↑↑↑↑↑cardiogenic and neurogenic
shock, if not tachy
Phenylephrineα↔ or ↓↑↑↑↓septic shock only, can use if tachy
Vasopressinvasopressin–↑↑↑ – or ↑septic only
Isoproterenolβ1, β2↑↓↑ 
Dobutamineβ1, β2 (less β2
than isoproterenol		↑↓↑cardiogenic and septic shock   At high doses, causes headaches, paresthesias, and muscle cramps Doesn’t work well if the patient on beta blocker, milrinone is similiar choice
Milrinoneinotrope, vasodilation,
PDE (phosphodiesterase
inhibitor)		↑↑–↑ 

α = smooth muscle contraction

β1 = positive chronography, dromotropic and ionotropic

β2 = smooth muscle relaxation

Remember:

  • BP = SBP/DBP
  • MAP = [SBP + (2 * DBP)]/3    (normal is 70-100)
    • Map is largely based off of DBP because most of cardiac cycle is in diastole (filling)
  • Cardiac Output (CO) = Sv + HR

Which pressor when:

  • Septic shock: norepinephrine is first line, +/- vasopressin +/- dopamine
  • Cardiogenic shock: dobutamine is first line, +/- IABP (intra-aortic balloon pump) +/- milrinone.
  • Post-op: phenylephrine
  • Post-code:epinephrine

I like these graphics, which came from here:

Shock

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Hypovolemic shock:

  • Restore intravascular volume and oxygen carrying capacity.
  • If hemoglobin < 7, administer blood products.
  • Patients may need pressers.

Obstructive shock:

  • Must treat actual obstruction.
  • Fluids may improve end-organ perfusion temporarily.

Vasodilatory shock:

  • Usually sepsis

Septic Shock:

Treat with sepsis bundles.

  • Within 3 hours:
    • Obtain labs.
    • Start broad-spectrum antibiotics, ideally within the first hours (obtain cultures first if possible, but do not wait if not)
    • Measure lactate.
    • Administer crystalloids for hypotension or lactate > 4.  Use of balanced crystalloids (Ringers, plasmalyte) leads to less acute kidney injury.  Avoid hydroxyethyl starches, +/- albumin. Usually 30mL/kg fluid bolus.
  • Within 6 hours:
    • Check on what you did initially.  See if it worked.
    • Vasopressors if hypotension not improved to keep MAP > 65.
      • Norepinephrine is drug of choice (vasopressin or dopamine may be considered)
      • Phenylephrine is not recommended unless CO is high and BP is low.
      • Vasopressin added to norepinephrine may improve outcomes
    • Recheck lactate, monitor CVP or SCVOO2.
  • Empiric antibiotics: usually vancomycin and cefepime, pip/tazo or imipenem or meropenem +/- antifungal.  Change with cultures.
    • Procalcitonin levels can give guidance to the effectiveness of empiric therapy.  Decreasing levels suggests response.
  • Corticosteroids if not responding to IV fluids.  Hydrocortisone is preferred. Avoid fludrocortisone.

Hypersensitivity Reactions

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Type 1 Hypersensitivity is IgE mediated.  It’s anaphylaxis and the one we’re most concerned with in critical care.

Treatment:

  • Epinephrine, Benadryl, albuterol or racepinephrine, IV fluids, and pressors
  • Steroids will help biphasic reaction, but not acute reaction.
  • Monitor for 4-6 hours. Keep overnight if you have to re-intervene.
  • Send home with 2 epi-pens, oral steroids for 3-5 days, H2RA antihistamines and Benadryl
  • A biphasic reaction can happen within 24-48 hours.  Symptoms are rash and swelling. This is a medical emergency. Call 9-1-1-.