Vasopressors

Norepinephrine

Indication

• Septic shock

Primary Receptor

• α1 >> β1

Relative Effects

• ↑↑↑SVR
• ↑HR
• ↑SV

Dosing

• Start 2mcg/min
  • Incr by 1-2mcg/min q3-5min prn
  • Max dose is 40mcg/min
• Replace volume before starting

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 - natriuresis
  • 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

Adverse Effects

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

Mechanism of Action

• 0-5mcg/kg/min
  • Vasodilation (renal, mesenteric, coronary)
• 5-10mcg/kg/min
  • Beta1, alpha1 agonist
    • Incr CO, contractility, vasoconstriction
• >10mcg/kg/min
  • Alpha effects predominate

Dobutamine

Indication

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

Dosing

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

Adverse Effects

• Modest incr in HR/BP
• PVCs
• B2 effect may result in vasodilation
  • Caution if sys BP <90

Mechanism of Action

• Primarily B1 (and B2) agonist
  • Increases CO via incr contractility

Phenylephrine

Indication

• Shock

Dosing

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

Adverse Effects

• Bradycardia
• If extravasates use phentolamine

Mechanism of Action

• Alpha agonist
  • Vasoconstriction w/ reflex decr HR
    • May decrease stroke volume

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