Review of Dopamine

Introduction

• Presenter: Eddie Watson
• Platform: ICU Advantage
• Topic: Dopamine
• Importance: Key role in critical care, ACLS, treating bradycardia, and shock

Dopamine Overview

• Category: Endogenous catecholamine
• Role in Body: Neurotransmitter in the brain, effects body-wide
• Precursor: To norepinephrine and epinephrine
• Form Used: Intravenous medication (does not cross the blood-brain barrier)
• Effects: Peripheral body controls

Mechanism of Action

• Receptors Affected:
  • Dopamine Receptors:
    • Located on smooth muscle, proximal renal tubules, collecting ducts
    • Leads to increased diuresis from kidneys
  • Beta Adrenergic Receptors:
    • Beta 1:
      • Increased chronotropy
      • Increased inotropy
      • In heart, increases heart rate and stroke volume → increased cardiac output and perfusion
      • In kidneys, stimulates renin release → increased blood volume
    • Beta 2: Bronchial smooth muscle relaxation, dilates airways
  • Alpha Adrenergic Receptors:
    • Alpha 1: Constriction of vascular smooth muscle, increased inotropy in myocardial tissue

Dose-Dependent Effects

• Lower Doses (<10 µg/kg/min): More beta-adrenergic stimulation
• Higher Doses (>10 µg/kg/min): More alpha-adrenergic activation
• Renal Dose Dopamine: Low dose (0.5–2 µg/kg/min) initially thought to benefit kidneys, later disproven

Pharmacokinetics

• Half-Life: Short, 1–5 minutes
• Administration: Continuous infusion
• Pre-mixed Bags: Commonly found in 400mg/250ml, 200mg/250ml, 800mg/250ml
• Dosing Range: 5–20 µg/kg/min (can go higher with increased risk)

Side Effects

• Common: Palpitations, nausea, vomiting, headaches, anxiety, chills, shortness of breath
• Serious: Tachyarrhythmias, ventricular arrhythmias, tissue necrosis (extravasation), asthmatic episodes, anaphylaxis

Uses in Critical Care

• Bradycardia:
  • Mechanism: Activation of beta 1 receptors → increased heart rate
  • Dose Range: 5–10 µg/kg/min
  • Recommended by AHA as an alternative when atropine is ineffective
• Shock:
  • Mechanism: Activation of alpha 1 (vasoconstriction) and beta 1 (increased cardiac output)
  • Dose Range: 10–20 µg/kg/min (start at 5 µg/kg/min and titrate up)
  • Watch for risks of tachyarrhythmias which can decrease cardiac output

Conclusion

• Wrap-up: Review of dopamine's effects, dosing, and critical care uses
• Engagement: Encouragement to like, comment, subscribe, share
• Support: Mention of benefits of Patreon and YouTube membership