A 52-year-old man with hypertension and type 2 diabetes undergoes femoral nerve block for total knee replacement at a private hospital in Bangalore. The anesthesiologist injects 40 mL of 0.75% ropivacaine. After 8 minutes, the patient becomes unresponsive, and the monitor shows ventricular fibrillation. ACLS is initiated. What is the most appropriate next step in management?

Explanation

## LAST-Induced Cardiac Arrest: Modified ACLS Protocol **Key Point:** When local anesthetic systemic toxicity (LAST) causes cardiac arrest, standard ACLS must be **modified**: lipid emulsion takes priority, CPR must be prolonged (60+ minutes), and epinephrine dosing is restricted. ### Why Cardiac LAST Is Different Ropivacaine (and especially bupivacaine) cause profound myocardial depression, bradycardia, and dysrhythmias refractory to standard resuscitation. The toxin must be removed from the myocardium via lipid sequestration before conventional drugs will be effective. | Feature | Standard Cardiac Arrest | LAST-Induced Cardiac Arrest | |---------|------------------------|----------------------------| | **First intervention** | Defibrillation (if VF) | IV lipid emulsion 20% bolus | | **Epinephrine dose** | 1 mg IV q 3–5 min | ≤1 mg total (max single dose 0.1 mg/kg) | | **CPR duration** | 20–30 min before pronouncement | 60+ min (lipid takes time to work) | | **Lipid emulsion role** | Not indicated | **Essential; given immediately alongside ACLS**| **High-Yield:** The American Heart Association (2015) and Association of Anaesthetists (UK) both recommend **immediate IV lipid emulsion 20% as part of ACLS in LAST-induced cardiac arrest**, not as a secondary measure. ### Cardiac LAST Management Algorithm ```mermaid flowchart TD A[LAST with cardiac arrest: VF/PEA/Asystole]:::urgent --> B[Call for lipid emulsion immediately]:::action B --> C[Start CPR + defibrillate if VF]:::action C --> D[Administer IV lipid emulsion 20%<br/>1.5 mL/kg bolus over 1 min]:::action D --> E[Continue CPR at high quality]:::action E --> F[Epinephrine: max 1 mg total<br/>or 0.1 mg/kg]:::action F --> G[Repeat lipid bolus q 5 min<br/>if no ROSC]:::action G --> H{ROSC achieved?}:::decision H -->|Yes| I[Transfer to ICU<br/>Extracorporeal support if available]:::action H -->|No| J[Continue CPR + lipid<br/>for 60+ minutes]:::action ``` **Clinical Pearl:** Extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass should be considered if ROSC is not achieved after 30 minutes of lipid-augmented ACLS, as these modalities can remove the local anesthetic while maintaining perfusion. **Warning:** Do NOT use standard epinephrine dosing (1 mg every 3–5 minutes) in LAST cardiac arrest—this can cause refractory dysrhythmias and myocardial injury. Restrict total epinephrine to ≤1 mg (or 0.1 mg/kg) during the entire resuscitation. **Mnemonic:** **LAST-ACLS = Lipid, Airway, Seizure control, Toxin removal; prolonged CPR, limit epinephrine, Supportive care, extended resuscitation** — think "extended" not "standard." [cite:American Heart Association Circulation 2015; Association of Anaesthetists AAGBI Guidelines 2010]