Vasopressors

Norepinephrine

Indication

• Septic shock

Primary Receptor

• α1 >> β1

Relative Effects

• ↑↑↑SVR
• ↑HR
• ↑SV

Dosing

• Start 2mcg/min
  • Incr by 1-2mcg/min
  • Max dose is 40mcg/min
• Replace volume before starting

Rate of Titration

• Q2-5 min

Adverse Effects

• If extravasates use phentolamine 5-10mg into affected area

Notes

More potent vasoconstrictor than dopamine and phenylephrine.

Dopamine

Indication

• Hypotension caused by:
  • Septic shock
  • MI
  • Trauma/spinal shock
  • Heart failure

Primary Receptor

• Low dose: DA, β1
• High dose: DA, α1 >> β1

Relative Effects

• Low dose: Natriuresis, ↑↑HR, ↑↑SV
• High dose: ↑SVR and ↑SV

Contraindication

• Tachyarrhythmias

Dosing

• Low dose:
  • 1-5 mcg/kg/min - Vasodilation (renal, mesenteric, coronary)
  • 5-10 mcg/kg/min - predominant β1
• High dose: 10-20 mcg/kg/min - predominant α1
• Titrate to clinical effect
  • Use lowest dose possible (prevent tachyphylaxis)
• May use in peripheral IV temporarily
  • Avoid using in same line as alkaline infusions

Rate of Titration

• Q2-5 min

Adverse Effects

• Low doses:
  • Hypotension
• High doses:
  • Hypertension, ectopic beats
• Tissue necrosis (if extravasates)
  • If occurs use phentolamine 5-10mg in affected area

Dobutamine

Indication

• Cardiogenic shock
• Low-output heart failure
• Tricyclic overdose

Primary Receptor

• β1
• β2

Relative Effects

• ↑↑↑SV
• ↑↑HR
• ↓SVR (transient, from β2 agonism)

Dosing

• 2-20mcg/kg/min
  • 10mcg works for most
• May use in peripheral IV

Rate of Titration

• Q2-5 min

Adverse Effects

• Tachyarrhythmias
• Myocardial ischemia
• Hypotension as β2 effect may result in vasodilation
  • Caution if SBP <90

Phenylephrine

Indication

• Neurogenic Shock

Primary Receptor

• α1

Relative Effects

• ↑SVR
• ↓HR (reflex bradycardia)

Dosing

• Start 100-200mcg/min then taper down
  • 40-60mcg/min works for most

Adverse Effects

• Baroreceptor-mediated reflex bradycardia
• If extravasates use phentolamine

Notes

• Useful for treatment of vasodilatory shock when norepinephrine or dopamine have precipitated tachyarrhythmias
• In pts with ↓LV function, unopposed α1 may lead to decreased CO or myocardial ischemia
  • However clinical trials do not support these effects when used in clinically appropriate dose range

Push Dose Pressors

• Use when need temporary BP or CO boost
  • Post-intubation hypotension
  • Propofol-induced hypotension
  • A-fib w/ hypotension
    • Easier to convert well-perfused heart

Epinephrine

• Mix 9mL of NS with 1mL of 1:10,000 epi
  • Now have 10mL of 10mcg/mL
    • Use 0.5-2mL q2-5min (similar to epi drip)
    • Same as 2% lido with epi
      • Ok to give peripherally
• Onset - 1min
• Duration - 5-10min

Phenylephrine

• Pure alpha (no effect on heart)
• Place 1mL of 10mg/mL in 100mL NS
  • Draw up 10mL
    • Now have 100mcg/mL
  • Use 0.5-2mL q2-5min
• Onset - 1min
• Duration - 20min

Source

• EBmedicine.net
• Tintinalli
• EmCrit Podcast 6