Drugs Used in Shock

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Drugs Used in Shock - Shocking Start!

Shock: critical circulatory failure causing tissue hypoperfusion. Early goal-directed therapy is key; target Mean Arterial Pressure (MAP) often >65 mmHg.

Types of Shock & Primary Hemodynamic Problem:

Shock TypePrimary ProblemExample(s)
Hypovolemic↓ Preload (↓ circulating volume)Hemorrhage, Dehydration
Cardiogenic↓ Contractility (pump failure)MI, Arrhythmia
Distributive↓ SVR (vasodilation, leaky vessels)Sepsis, Anaphylaxis
Obstructive↓ CO (physical obstruction to flow)PE, Tamponade

Key Adrenergic Receptors Targeted:

  • α1: Vasoconstriction (arterial & venous) → ↑SVR, ↑BP.
  • β1: Heart → ↑Heart rate (chronotropy), ↑Contractility (inotropy).
  • β2: Smooth muscle relaxation → Vasodilation (skeletal muscle), Bronchodilation.
  • D1 (Dopamine): Renal & mesenteric vasodilation (low "renal dose" dopamine - use is controversial).

⭐ Septic shock is the most common type of distributive shock, characterized by profound vasodilation and increased capillary permeability, leading to relative hypovolemia.

Drugs Used in Shock - Pressure Up!

DrugReceptor ActivityMAPCOHRSVRKey IndicationsMajor Side Effects
Norepinephrineα1 > β1↑↑↔/↓↔/↓↑↑Septic shock (1st line), other vasodilatory shockPeripheral ischemia, Arrhythmias
Epinephrineα1, β1, β2 (dose-dep.)↔/↑Anaphylaxis, Cardiac arrest, Septic shock (adjunct)Tachyarrhythmias, HTN, Myocardial ischemia
DopamineD1 > β1 > α1 (dose-dep.)VarVarVarVarShock (2nd line if NE unavailable/bradycardia), Symptomatic bradycardiaTachyarrhythmias, Nausea, Ischemia
Phenylephrineα1 (pure agonist)Neurogenic shock, Sepsis-induced hypotension (if tachyarrhythmias with NE)Reflex bradycardia, Reduced CO, Ischemia
VasopressinV1 (vascular smooth muscle)Refractory septic shock (adjunct), GI hemorrhageMyocardial/Splanchnic ischemia, Hyponatremia
  • Low (1-5 mcg/kg/min): D1 (Renal)
  • Moderate (5-10 mcg/kg/min): β1 (Cardiac)
  • High (>10-20 mcg/kg/min): α1 (Vasopressor)

⭐ Norepinephrine is the first-line vasopressor for septic shock.

Vasopressor Properties and Effects Chart

Simplified Vasopressor Strategy in Shock:

Drugs Used in Shock - Pump Power!

Key inotropes improve cardiac contractility in shock.

FeatureDobutamineMilrinoneLevosimendan
Mechanism$\beta_1$ agonist (📌 Do-Beta-mine); ↑ cAMPPDE3 inhibitor (📌 Mill-PDE-none); ↑ cAMPCa2+ sensitizer (📌 Levo-Sensi-dan), K+ATP opener
Effects↑ Inotropy, mild ↑ Chrono, mild ↓ SVR↑ Inotropy, Lusitropy; Vasodilation (↓SVR/PVR)↑ Inotropy; Vasodilation (coronary/systemic/pulmonary)
IndicationsCardiogenic shock (low CO, ok BP), severe HFAcute HF, shock (if $\beta$-blocked)Acute decomp. HF; shock
Side EffectsTachycardia, Arrhythmias, Hypotension (if hypovolemic)Hypotension, Arrhythmias, ThrombocytopeniaHypotension, Headache, HypoK+, Arrhythmias

Inotropes and Vasopressors: Dosing and Half-life

Drugs Used in Shock - Helper Heroes!

  • Corticosteroids (for Septic Shock):
    • Indication: Septic shock with persistent hypotension despite adequate fluids & vasopressors.
    • Drug: Hydrocortisone IV is preferred.
    • Dose: 200-300mg/day (e.g., 50mg IV q6h or as a continuous infusion).
    • Mechanism: Modulate inflammation, ↑vascular reactivity to vasopressors.
    • Goal: Earlier shock reversal, ↓ vasopressor duration.
    • Taper gradually once vasopressors weaned.

⭐ Corticosteroids are considered in septic shock refractory to fluids and vasopressors, particularly if vasopressor requirements are escalating.

High‑Yield Points - ⚡ Biggest Takeaways

  • Norepinephrine is the first-line vasopressor in septic shock.
  • Dobutamine is the inotropic agent of choice in cardiogenic shock with low cardiac output.
  • Epinephrine is the drug of choice for anaphylactic shock and second-line in septic shock.
  • Vasopressin is an adjunct in refractory septic shock to spare norepinephrine.
  • Phenylephrine is used in neurogenic shock or if tachyarrhythmias are a concern.
  • Milrinone (PDE3 inhibitor) is an inodilator for refractory cardiogenic shock.
  • Target MAP >65 mmHg and monitor lactate clearance with vasopressors.

Practice Questions: Drugs Used in Shock

Test your understanding with these related questions

A 30-year-old female patient developed features of septicemia, presenting with shock characterized by hypotension and low urine output, and was being treated for colonic necrosis. What is the most likely management?

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Flashcards: Drugs Used in Shock

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Drug of choice for cardiogenic shock -

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Drug of choice for cardiogenic shock -

Norepinephrine

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