About This Calculator

The Lidocaine Infusion Calculator helps healthcare professionals determine the appropriate loading dose and maintenance infusion rate for administering intravenous lidocaine, primarily for the treatment of ventricular arrhythmias. By inputting patient-specific data, this tool provides key outputs to guide safe and effective administration, streamlining a critical aspect of cardiac care.

Calculator Outputs Explained

After entering the required patient information, the calculator provides the following key dosing parameters:

• Total Loading Dose (Bolus): The total mass of lidocaine (in mg) to be administered as an initial bolus. This is calculated based on the patient’s weight and the selected dose in mg/kg. This dose should be given slowly over 1-2 minutes.
• Volume for Bolus: The volume of the selected lidocaine solution (in mL) that corresponds to the total loading dose. This helps ensure accurate measurement and administration.
• Maintenance Infusion Rate: The rate (in mL/hr) at which the continuous infusion should be run on an infusion pump to deliver the desired maintenance dose in mg/min.

How to Use the Calculator

Follow these steps for an accurate calculation:

1. Enter Patient Weight: Input the patient’s weight and select the appropriate unit (kg or lbs). The calculator will convert lbs to kg for dosing calculations.
2. Select Lidocaine Concentration: Choose from standard premixed concentrations (e.g., 2g in 250 mL) or select “Custom” to enter the specific mass (mg) and volume (mL) of your institution’s preparation.
3. Input Loading Dose: Enter the desired loading dose in mg/kg. The typical range is 1-1.5 mg/kg.
4. Input Maintenance Infusion: Enter the desired maintenance infusion rate in mg/min. The typical range is 1-4 mg/min.
5. Review Results: The calculator will instantly display the calculated bolus dose, bolus volume, and infusion rate for clinical use. Always verify calculations before administration.

Lidocaine Dosing Overview

Lidocaine is a class IB antiarrhythmic agent used to treat ventricular tachycardia and fibrillation. Dosing involves a two-stage process:

• Loading Dose (Bolus): An initial bolus is given to rapidly achieve therapeutic plasma concentrations. The standard dose is 1-1.5 mg/kg. If the arrhythmia persists, additional boluses of 0.5-0.75 mg/kg can be administered every 5-10 minutes, up to a total cumulative dose of 3 mg/kg.
• Maintenance Infusion: Following the bolus, a continuous infusion is started to maintain therapeutic levels. The standard rate is 1-4 mg/min. Dose adjustments are crucial in patients with heart failure, liver disease, or in the elderly, who may require a 50% reduction in dose due to decreased clearance.

Adjustments and Re-bolusing

Managing a lidocaine infusion requires ongoing assessment. If the initial bolus and infusion do not suppress the arrhythmia, a re-bolus may be necessary. Administer a smaller bolus of 0.5-0.75 mg/kg while the maintenance infusion is running. It is critical to not exceed a total loading dose of 3 mg/kg within a 1-hour period to avoid toxicity. Always monitor the patient’s ECG, blood pressure, and neurological status closely during re-bolusing and dose adjustments.

Managing Infusion Interruptions

If the maintenance infusion is interrupted for a short period, it may need to be re-initiated with a small bolus to re-establish therapeutic levels, depending on the duration of the interruption and the patient’s clinical status. Consult institutional protocols or a pharmacist for specific guidance. For prolonged interruptions, a full re-loading dose may be considered, but caution is advised to prevent drug accumulation.

Safety Alerts and Contraindications

Lidocaine administration requires careful patient selection and monitoring.

• Contraindications: Do not use in patients with severe heart block (second- or third-degree AV block without a pacemaker), Stokes-Adams syndrome, Wolff-Parkinson-White syndrome, or a known hypersensitivity to amide-type anesthetics.
• Signs of Toxicity: Be vigilant for signs of CNS toxicity (drowsiness, confusion, paresthesias, slurred speech, seizures) and cardiovascular toxicity (bradycardia, hypotension, arrhythmias). Toxicity is related to plasma concentration, and risk increases with high doses, rapid administration, and in patients with impaired clearance.
• Dose Adjustments: Reduce both loading and maintenance doses by up to 50% in patients with severe hepatic impairment, congestive heart failure, shock, or in those over 70 years of age.

Frequently Asked Questions

References