Lidocaine

• Class IB antidysrhythmic agent

• Blocks sodium channels of the heart's conduction system
• Slows conduction in the atria, ventricles, and Purkinje fibers
• Reduces automaticity in the ventricles
• Raises electrical stimulation threshold of the ventricles during diastole
• Accelerates repolarization shortening action potential duration
• (no anticholinergic effects)

Antidysrhythmic medication for:

• Ventricular ectopy (PVC's)

• Stable ventricular tachycardia
• alternative to amiodarone during pulseless ventricular tachycardia/fibrillation code

• Onset: 45 – 90 seconds IV push
• Duration: 10 – 20 minutes IV push
• Half-Life: 1.5 – 2 hours
• Metabolism:  by liver

• Drowsiness, confusion, paresthesia

• (early) agitation, confusion
• (late) seizures, coma, respiratory arrest

• Prophylactic use in acute MI is contraindicated.
• Ideoventricular rhythm
• Complete (3rd degree) heart block
• Hypersensitivity to __amide anesthetics
• Safety during pregnancy or lactation (class B) not established.

• Intravenous: 1 – 1.5 mg/kg first IV push or intraosseous during codes; second dose may be 0.5 – 0.75 mg/kg IV or IO
• IV Drip:  1 – 4 mg/min diluted in D₅W or NS
• (Can be administered via endotracheal tube, but not a preferred route)

• Drug Interactions:  1) Lidocaine enhances effects of tocainide and mexiletine; 2) Barbiturates decrease effect of lidocaine; 3) Lidocaine is enhanced by cimetidine, beta blockers, phenytoin, quinidine, and procainamide.
• Incompatibilities with intravenous infusion include phenytoin, ampicillin, cefazolin, amphotericin B, and thiopental.
• Check BP and cardiac monitor prior to administration of lidocaine.
• For stable patients, doses should be given slow IV push at 25 mg/minute.
• Monitor blood pressure and cardiac monitor during therapy with lidocaine.
• Assess neurological and respiratory status frequently for signs of toxicity.
• When treating a patient for ventricular dysrhythmias with lidocaine, an IV infusion (drip) must be started soon after the bolus or serum level will drop below therapeutic range and ventricular dysrhythmias will return.
• Therapeutic serum level is 1.5 – 5 mcg/ml.
• If patient appears upset or agitated, consider lidocaine toxicity.  If toxicity is evident, simply discontinue IV infusion–serum levels drop in 10-20 minutes.