Pediatric emergency medicine trisk 1724 1724
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combination) to control rate until the patient is fully assessed for a possible clot in
the left atrium. Calcium channel blockers are not given to patients less than 2
years of age. Amiodarone or sotalol are commonly used for chronic control atrial
fibrillation and when used acutely may cause conversion to sinus rhythm.
Wide Complex, Irregular Tachycardia. A wide rhythm, which is irregularly
irregular may be VT or atrial fibrillation with Wolff–Parkinson–White (WPW)
and will require cardioversion/defibrillation. Assess for hemodynamic stability
and proceed according to the PALS algorithms. WPW with atrial fibrillation
should be cardioverted, just as for atrial fibrillation without WPW. Do not give
adenosine to any patient with a wide complex irregular rhythm (see adenosine
below).
Narrow Complex, Regular Tachycardia. Evaluation of a relatively stable patient
with narrow complex tachycardia, includes asking the patient to perform a vagal
maneuver while recording the rhythm. An external defibrillator/pacer should be
available. The vagal technique chosen should be appropriate for the age of the
patient. In infants, knee to chest position, rectal stimulation with a thermometer,
or the diving reflex may be used. To elicit the diving reflex in an infant, gently
place a slurry of ice and water in a plastic bag over the nose and eyes of the
patient for no more than 35 seconds. Older children and adolescents may perform
knee to chest, hold their breath, immerse their face in cold water, or bear down. If
vagal maneuvers are unsuccessful in converting tachycardia to sinus rhythm, IV
access should be obtained for administration of adenosine.
Adenosine is the drug of choice in regular, narrow complex tachycardia. It is an
amino acid that is rapidly metabolized by erythrocytes and the endothelium,
giving it a half-life of about 9 seconds. Therefore, adenosine must be delivered
via a large-bore IV placed as close to the heart as possible, followed by rapid or
simultaneous flush of 10 mL normal saline to ensure that the medication reaches
the heart before it is metabolized. The starting dose of adenosine is 0.1 mg/kg IV,
followed by 0.2 mg/kg IV as needed three times. In patients weighing more than
50 kg, give 6 mg IV followed by 12 mg IV. One-third to one-half of the normal
adenosine dose should be used when given to heart transplant recipients.
Adenosine has reportedly been effective when administered through an
intraosseous line but results are inconsistent.
Adenosine briefly blocks conduction in the atrioventricular (AV) node causing
disruption of any tachycardia circuit that depends on AV nodal conduction for
perpetuation of the tachycardia. Interpretation of the adenosine’s effect on
conduction cannot be analyzed on the bedside monitor screens, so it is important
