In advanced cardiac life support (ACLS), what is the recommended first-line vasopressor and its dosing interval during cardiac arrest?

Explanation

## First-Line Vasopressor in ACLS: Epinephrine **Key Point:** Epinephrine (adrenaline) 1 mg IV or intraosseous (IO) every 3–5 minutes is the first-line vasopressor for cardiac arrest management in ACLS protocols. **High-Yield:** Epinephrine is indicated for: - Ventricular fibrillation (VF) - Pulseless ventricular tachycardia (pVT) - Asystole - Pulseless electrical activity (PEA) ### Mechanism of Action 1. **α-adrenergic effects (predominant):** Peripheral vasoconstriction → increased diastolic pressure → improved coronary and cerebral perfusion 2. **β-adrenergic effects:** Increased heart rate and contractility (less important during arrest) **Clinical Pearl:** The α-adrenergic effects are crucial for resuscitation; they increase the aortic diastolic pressure, which drives blood to the coronary arteries during the relaxation phase of chest compressions. ### ACLS Epinephrine Protocol ```mermaid flowchart TD A[Cardiac Arrest]:::outcome --> B{Rhythm?}:::decision B -->|VF/pVT| C[Defibrillate immediately]:::action B -->|Asystole/PEA| D[Continue CPR]:::action C --> E[Epinephrine 1 mg IV/IO]:::action D --> E E --> F[Repeat every 3-5 minutes]:::action F --> G[Continue ACLS protocol]:::action ``` ### Comparison with Other Vasopressors | Agent | Dose | Interval | Role in ACLS | | --- | --- | --- | --- | | **Epinephrine** | **1 mg IV/IO** | **Every 3–5 min** | **First-line** | | Vasopressin | 40 units IV/IO | Single dose (alternative) | Rarely used now; removed from most recent guidelines | | Noradrenaline | 0.1–0.5 mcg/kg/min | Continuous infusion | Post-resuscitation; not for acute arrest | | Dopamine | 5–10 mcg/kg/min | Continuous infusion | Post-resuscitation; not for acute arrest | **Mnemonic:** **E-1-3-5** — **E**pinephrine 1 mg every 3–5 minutes. **Warning:** Vasopressin is no longer recommended as a first-line agent in current ACLS guidelines (2020 update onwards). Do not confuse with older protocols. [cite:AHA ACLS Guidelines 2020 Update]