Vasopressors and inotropic support

Vasopressors and inotropic support

Vasopressors and inotropic support

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Goals of Therapy - Squeeze the Pipes

  • Primary Goal: Maintain Mean Arterial Pressure (MAP) ≥ 65 mmHg to ensure adequate organ perfusion.
  • MAP is estimated as $1/3(SBP) + 2/3(DBP)$.

⭐ Add Dobutamine for persistent hypoperfusion (e.g., elevated lactate) and evidence of myocardial dysfunction (e.g., low cardiac index on echo) despite achieving the MAP goal.

Norepinephrine - The Alpha Dog

  • First-line vasopressor for septic shock (Surviving Sepsis Campaign).
  • Mechanism: Potent α1-agonist >> β1-agonist activity.
    • α1 stimulation → intense peripheral vasoconstriction → ↑ SVR & ↑ MAP.
    • β1 stimulation → modest ↑ inotropy & chronotropy → ↑ Cardiac Output.
  • Hemodynamic Profile:
    • Primarily ↑ MAP through ↑ SVR.
    • Cardiac output may increase, stay stable, or decrease (due to reflex bradycardia).

Exam Favorite: Norepinephrine is superior to dopamine for septic shock as it's associated with a lower risk of arrhythmias and improved mortality.

Adjunctive Agents - The Backup Squeezers

  • Vasopressin: For refractory shock to ↓ norepinephrine needs. Acts on V1 receptors causing pure vasoconstriction. Typical dose is 0.03 units/minute.
  • Epinephrine: Add-on therapy if MAP targets are unmet. Potent β1 and α1 effects, but risk of tachyarrhythmias and ↑ lactate.
  • Corticosteroids: Consider for refractory shock despite adequate fluids and pressors.
    • Hydrocortisone IV, often 200 mg/day.

⭐ For patients on norepinephrine or epinephrine, adding vasopressin is associated with a lower rate of atrial fibrillation. It acts as a catecholamine-sparing agent.

Inotropic Support - Whip the Heart

Used for persistent hypoperfusion and cardiac dysfunction despite adequate fluid and vasopressor therapy (MAP ≥65 mmHg).

  • Goal: Increase cardiac output (CO) and improve end-organ perfusion.
  • Primary Agent: Dobutamine
    • Mechanism: Primarily a β1-agonist → ↑ contractility & heart rate.
    • Dosing: 2-20 mcg/kg/min.
  • Alternative: Epinephrine
    • Provides both potent inotropic (β1) and vasopressor (α1) support.

⭐ Dobutamine's β2-agonist activity can cause peripheral vasodilation, potentially worsening hypotension. Ensure patient is on a vasopressor first.

Monitoring & Titration - Watchful Waiting

  • Goal: Titrate to the lowest effective dose to maintain target MAP (>65 mmHg) and ensure adequate end-organ perfusion.
  • Frequent Reassessment:
    • Arterial Line: For continuous, real-time MAP monitoring.
    • Lactate Clearance: Check q4-6h; indicates resolving shock.
    • Urine Output: Target >0.5 mL/kg/hr.
    • CVP & ScvO2: Targets 8-12 mmHg & >70% respectively.
  • Weaning: Gradually ↓ dose when stable and lactate normalizes. Avoid abrupt discontinuation.

⭐ Persistent ↑ lactate despite an adequate MAP is a poor prognostic sign, suggesting ongoing tissue hypoperfusion or mitochondrial dysfunction.

Early Vasopressor Initiation and Titration in Septic Shock

High‑Yield Points - ⚡ Biggest Takeaways

  • Norepinephrine is the first-line vasopressor for septic shock, targeting a MAP ≥65 mmHg.
  • Vasopressin is a common second-line agent added to norepinephrine; it is not titrated.
  • Add dobutamine for signs of myocardial dysfunction (e.g., low cardiac output) despite adequate fluid and vasopressor therapy.
  • Epinephrine can be an alternative or add-on to norepinephrine.
  • An arterial line is essential for accurate, continuous blood pressure monitoring.
  • Watch for peripheral ischemia as a major side effect.

Practice Questions: Vasopressors and inotropic support

Test your understanding with these related questions

A 28-year-old research assistant is brought to the emergency department for severe chemical burns 30 minutes after accidentally spilling hydrochloric acid on himself. The burns cover both hands and forearms. His temperature is 37°C (98.6°F), pulse is 112/min, respirations are 20/min, and blood pressure is 108/82 mm Hg. Initial stabilization and resuscitation is begun, including respiratory support, fluid resuscitation, and cardiovascular stabilization. The burned skin is irrigated with saline water to remove the chemical agent. Which of the following is the most appropriate method to verify adequate fluid infusion in this patient?

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Flashcards: Vasopressors and inotropic support

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Do patients with point of service (POS) insurance plans require PCP referral for specialist visits?_____

TAP TO REVEAL ANSWER

Do patients with point of service (POS) insurance plans require PCP referral for specialist visits?_____

Yes

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