Procainamide

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

Procainamide blocks sodium channels which prolongs the refractory period of both the atria and the ventricles. It also reduces the speed of intraventricular conduction, which prolongs the QT, QRS, and PR intervals.

Procainamide Indications

Now let's take a look at procainamide indications.

For pediatric patients, procainamide can be used to treat a variety of atrial and ventricular arrhythmias. It can also be used to treat hemodynamically stable SVT refractory to vagal maneuvers and the medication adenosine, because procainamide can terminate SVT that is resistant to other medications.

Procainamide is also effective at treating atrial flutter, atrial fibrillation, and suppressing pulsed V-tach.

Procainamide Precautions and Contraindications

Warning: Caution must be taken when administering procainamide, as it shortens the effective refractory period of the AV node and increases AV nodal conduction.

Procainamide can also increase heart rate when used to treat ectopic atrial tachycardia and atrial fibrillation. And, like amiodarone, may also increase the risk of polymorphic V-tach, also commonly known as torsades de pointes.

Due to procainamide's potent vasodilating effects, this medication can cause hypotension in children. Also, the dose should be reduced for patients with poor renal or cardiac rhythm.

Pediatric Dosage of Procainamide

Now let's look at the pediatric dosage for procainamide.

The initial dose of procainamide should be an infusion of 15mg/kg over a period of 30 to 60 minutes with continuous ECG monitoring and frequent blood pressure monitoring.

It's also important that procainamide be administered by slow infusion to avoid toxicity from heart block, hypotension, and the prolongation of the QT interval.

A Word About Identifying Respiratory Problems by Type

We'll be digging into respiratory arrest and specific upper and lower airway issues in the following Case Studies section of your ProPALS course. So, consider this a bit of a preview of things to come, but with some additional information thrown in.

You may remember from the previous lesson that respiratory distress or failure can be classified as one or more of the following types:

• Upper airway obstruction
• Lower airway obstruction
• Lung tissue disease
• Disordered control of breathing

In the last Word, we went into detail on signs and symptoms of upper and lower airway obstruction. In this Word, we'll dig deeper into the remaining two types: lung tissue disease and disordered control of breathing.

Lung Tissue Disease

Lung tissue disease is a condition that's used to describe a disease involving the substance (such as parenchyma or tissue) of the lung. While in this state, the pediatric patient's lungs become stiff due to fluid accumulation in the alveoli, interstitium, or both, and requires increased respiratory effort during inspiration and exhalation. Therefore, retractions and accessory muscle use are common.

Hypoxemia is often distinct due to alveolar collapse or reduced oxygen diffusion caused by pulmonary edema fluid and inflammatory debris in the alveoli. Tachypnea is also common and often quite noticeable as well.

A pediatric patient will frequently attempt to counteract alveolar and small airway collapse by increasing their efforts to maintain an elevated end-expiratory pressure, which is often manifested by grunting respirations.

The signs of lung tissue disease include:

• Tachypnea (often evident)
• Increased respiratory effort
• Grunting
• Crackles, or rales, and decreased air movement
• Diminished breath sounds
• Tachycardia
• Hypoxemia (despite the administration of supplementary O2

Disordered Control of Breathing

While in the state of disordered control of breathing, there is inadequate respiratory effort. Often the parent will say something like, their child is breathing funny or not breathing normally.

There can be periods of increased respiratory rate, effort, or both, and followed by decreased rate, effort, or both. Also common is that the patient's respiratory rate or effort may be continuously inadequate. The net effect is often hypoventilation leading to hypoxemia and hypercarbia.

The signs of disordered control of breathing include:

• Variable or irregular respiratory rate and pattern (tachypnea alternating with bradypnea)
• Variable respiratory effort
• Shallow breathing with inadequate effort (often resulting in hypoxemia and hypercarbia)
• Central apnea (such as apnea without any respiratory effort)
• Normal or decreased air movement