Lidocaine

In this lesson, we'll go over the medication lidocaine and all of its effects, including indications, precautions and contraindications, and pediatric dosages.

Lidocaine works by bringing about negative inotropic (meaning, modifying the force or speed of the contraction of muscles) effects and antiarrhythmic actions in the heart which weaken the force of muscular contractions and can calm erratic and uncoordinated electro myocardial activity.

In other words, lidocaine decreases automaticity and suppresses ventricular arrhythmias.

Lidocaine Indications

Now let's take a look at lidocaine indications.

Due to lidocaine's antiarrhythmic properties, the primary use of lidocaine is for cardiac arrest from ventricular fibrillation (VFib) and pulseless ventricular tachycardia.

Lidocaine Precautions and Contraindications

Lidocaine has one important precaution and contraindication that we should note.

Lidocaine would be contraindicated if the patient has a known hypersensitivity to lidocaine or its derivatives, such as xylocaine, novocaine (also known as procaine), and similar drugs.

Pediatric Dosage of Lidocaine

Now let's look at the pediatric dosage of lidocaine.

For pediatric dosages, the initial lidocaine IV or IO dose is 1mg/kg. A maintenance infusion can be given at between 20 and 50mcg/kg per minute.

A Word About Medication Therapy for Shock in Pediatric Patients

We'll be getting more into the treatment of shock in pediatric patients in the next section – Case Studies – however, consider this Word as either a preview of things to come or supplemental information that could come in handy later.

Medication therapy is used in the management of shock to affect heart rate, myocardial contractility, and vascular resistance. The choice of agent, or agents, will be determined by the child's physiologic state.

Vasoactive agents are indicated when shock persists despite adequate volume
resuscitation to optimize preload. For example, a pediatric patient with septic shock who remains hypotensive with signs of vasodilation despite the administration of fluid boluses could benefit from a vasoconstrictor.

The administration of vasoactive medications can be potentially harmful if the pediatric patient hasn't been sufficiently fluid resuscitated first. However, in pediatric patients with cardiogenic shock, vasoactive agents should be used early since fluid resuscitation isn't key to improving myocardial function and may even contribute to pulmonary edema and respiratory failure.

Most pediatric patients with cardiogenic shock will benefit from a vasodilator (provided that the patient's blood pressure is sufficient) to decrease systemic vascular resistance (SVR) and increase cardiac output and tissue perfusion.

lnotropes, phosphodiesterase inhibitors (such as the inodilator milrinone), vasodilators, and vasopressors are classes of pharmacologic agents that are commonly used in the treatment of shock in pediatric patients. Now let's look at vasoactive therapies typically used in the treatment of pediatric shock.

Vasoactive Medications by Class and Pharmacologic Effects

Class: Inotropes

Medication:

• Dopamine
• Epinephrine
• Dobutamine

Effects:

• Increase cardiac contractility
• Increase heart rate
• Produce variable effects on SVR

Class: Phosphodiesterase Inhibitors (lnodilators)

Medication:

• Milrinone

Effects:

• Decrease SVR
• Improve coronary artery blood flow
• Improve contractility

Class: Vasodilators

Medication:

• Nitroglycerin
• Nitroprusside

Effects:

• Decrease SVR
• Decrease venous tone

Class: Vasopressors (vasoconstrictors)

Medication:

• Epinephrine (dosages >0.3 mcg/kg per minute)
• Norepinephrine
• Dopamine (dosages > 10 mcg/kg per minute)
• Vasopressin

Effects:

• Increase SVR
• Increase myocardial contractility (except vasopressin)

For more specific categories of shock, lifesaving diagnostic assessments and therapeutic interventions may be required that may be beyond the scope of practice of many PALS providers.

For example, there's a chance you may not be trained to interpret an echocardiogram or perform a thoracostomy or pericardiocentesis. Which is why it's important to recognize your own limitations to your own scope of practice and ask for help when needed.

Early subspecialty consultation (such as pediatric critical care, pediatric cardiology, and pediatric surgery) is an essential component of shock management in pediatric patients and can influence the outcome.