Bradydysrhythmias in children most often result from which cause?

• A. Hyperkalemia
• B. Hypothyroidism
• C. Severe hypoxia
• D. Anemia

Answer: (C)

Severe hypoxia is the most common reason bradydysrhythmias occur in children because when oxygen delivery to the heart and brain drops, the autonomic nervous system shifts toward vagal dominance and the sinus/AV node automaticity slows. In pediatric emergencies, bradycardia often appears as a late sign of escalating respiratory failure, airway obstruction, or severe hypoxemia, and improving oxygenation and ventilation usually reverses the rhythm disturbance. Hyperkalemia can slow conduction and cause bradycardia but is less common in kids without specific settings like renal failure or toxins. Hypothyroidism causes bradycardia, but it is typically a chronic finding, not an acute emergency. Anemia tends to produce tachycardia as a compensatory mechanism rather than bradycardia.