June 9, 2023

Dear colleagues:

Welcome to UH EMS Institute’s Pharmacy Phriday. In the last installment, we reviewed Tetracaine and its use for eye injuries. In this week’s installment, we will review Lidocaine, another medication in the “caine” family that may be known to older providers as an antiarrhythmic but is now considered more as an anesthetic used during IO infusions. Like Tetracaine, Lidocaine works by blocking sodium channels that prevent depolarization of the nerves causing a local anesthesia effect. 

The prevalence of the use of the intraosseous (IO) route for emergency administration of medications continues to grow. Studies can be found that look at its use for trauma patients and unconscious or semi-conscious patients with difficult IV access. Within the UH protocols, an IO is indicated for life-threatening illness or injury in an adult or child where traditional vascular access has failed or is unlikely. Establishing an IO is a quick procedure with typically high success rates.

Pain associated with an IO insertion and infusion in conscious patients is a well-documented reality that must be addressed. This pain can be substantially reduced by the use of Lidocaine through the IO port prior to the infusion. The injection of 2% intravenous Lidocaine into the IO needle for relief of injection pain has become a standard practice and is approved within the UH protocols for the paramedic and advanced EMT provider.

The dosage for Lidocaine for this use with an IO is 20-40 mg (1-2 ml as provided in the 2% solution), with a slow push to allow it to work. In the pediatric patient, the dosing is 0.5 mg/kg, up to a maximum pf 40 mg, again as a slow push. Lidocaine has a rapid onset, but protocols and other resources suggest allowing the medication to dwell shortly to allow it to take effect before flushing, some suggesting up to two minutes.  

As a sodium channel blocker that affects the depolarization in the cardiac action potential, Lidocaine can also be used as an antiarrhythmic. The medication will suppress the heart’s ventricles irritability and raise the fibrillation threshold in cases of pulseless V-Fib/V-Tach as well as wide complex tachycardias with a pulse. Lidocaine should only be used in these instances when amiodarone is not available or if its use is contraindicated. One of those contraindications to the use of amiodarone mentioned in our UH protocols is in the pregnant patient. 

When using Lidocaine for cardiac dysrhythmias in the adult patient, the dose is 1.0-1.5 mg/kg, IV/IO, followed by a half dose of 0.5-0.75 mg/kg every 5-10 minutes to a max dose of 3 mg/kg. Half dosing is recommended for patients over 70 years of age, those with liver disease, or those suffering from heart failure. 

When using Lidocaine for dysrhythmias in the pediatric patient, the dosing is 1.0 mg/kg, followed by 0.5 mg/kg in 5-10 minutes to a max dose of 3 mg//kg. Per UH protocols, if the pediatric patient converts to a non-bradycardic rhythm, a maintenance dose is given by bolus at 0.5 mg/kg IV/IO every 10 minutes up to two times.

As with many other antiarrhythmics, Lidocaine is contraindicated in cases of bradycardia, AV blocks, idioventricular escape rhythms, or in cases of shock or hypotension. Side effects with the use of Lidocaine include many of these contraindications, as well as effects of its anesthetic effect that could include nausea and vomiting, dizziness, slurred speech, drowsiness, confusion, respiratory depression, or seizures. 

Till the next installment, stay safe!

Sincerely,



The UH EMS-I Team

University Hospitals