Pediatric bradycardia is a heart rate slower than the expected normal range for a child’s age. It becomes a medical emergency when the slow rate compromises the body’s ability to circulate blood effectively, leading to instability. The Pediatric Advanced Life Support (PALS) Bradycardia with a Pulse Algorithm provides a systematic framework for managing this situation. This protocol is designed for unstable patients who still possess a palpable pulse, distinguishing it from the cardiac arrest algorithm. It focuses on identifying and treating the underlying cause, which is usually respiratory failure or shock rather than a primary cardiac issue.
Criteria for Initiating the Algorithm
The decision to initiate the PALS bradycardia algorithm rests on two concurrent findings: an abnormally slow heart rate and signs of cardiopulmonary compromise. Bradycardia is defined by age-specific heart rate thresholds. For infants up to three years old, a rate below 100 beats per minute (bpm) is considered bradycardic. For children aged three to nine years, the threshold drops to below 60 bpm, and adolescents require intervention if their heart rate falls below 50 bpm.
A slow heart rate alone does not mandate the use of this algorithm; the patient must also display signs of instability, indicating poor cardiac output. These signs include hypotension (blood pressure too low to perfuse organs adequately) and acutely altered mental status (such as unresponsiveness or confusion). Signs of shock, such as weak pulses, cold or mottled skin, and prolonged capillary refill time, also signal circulatory failure. When bradycardia is accompanied by these signs of poor perfusion, the patient is considered symptomatic and unstable, requiring immediate intervention.
Essential Steps Before Advanced Intervention
Upon recognizing unstable bradycardia, the immediate priority is to address inadequate oxygenation, the most common underlying cause. Initial actions focus on the foundational supportive measures of airway, breathing, and circulation. Establishing a patent airway and ensuring effective breathing are the first steps, often requiring assisted ventilation with a bag-mask device if the child is not breathing adequately.
Supplemental oxygen should be administered to achieve a normal saturation level, as hypoxia is the most frequent trigger for secondary bradycardia. Continuous monitoring of the heart rhythm, blood pressure, and oxygen saturation must be established immediately to track the patient’s response. Securing intravenous (IV) or intraosseous (IO) access is a parallel task that allows for the rapid administration of fluids and medications later in the algorithm. These initial supportive measures often resolve the bradycardia, making advanced treatments unnecessary.
Advanced Interventions within the Protocol
If initial supportive measures fail to improve the heart rate and signs of instability persist, the algorithm moves to pharmacologic and electrical therapies. Epinephrine is the primary medication used in refractory unstable bradycardia to increase heart rate and improve contractility. The standard intravenous or intraosseous dose is 0.01 mg/kg of the 1:10,000 concentration, which can be repeated every three to five minutes as needed. This medication acts as a potent adrenergic agonist.
Atropine may be considered if the bradycardia is suspected to be caused by increased vagal tone or a primary atrioventricular (AV) block. The recommended dose is 0.02 mg/kg, administered intravenously or intraosseously. There is a minimum single dose of 0.1 mg and a maximum single dose of 0.5 mg, which can be repeated once. Atropine blocks the effects of the vagus nerve.
Transcutaneous pacing (TCP) is another option for advanced treatment, particularly when the bradycardia is due to a primary heart block unresponsive to Atropine. TCP involves delivering electrical impulses through the chest wall to stimulate a heart contraction. Pacing efficacy is lower in pediatric patients compared to adults and is generally not effective if the bradycardia is caused by hypoxia or metabolic derangement. TCP should be considered only after medication and correction of reversible causes have failed, or if the rhythm is a complete heart block.
Transitioning to Cardiac Arrest Management
The management of bradycardia with a pulse has a distinct endpoint when the patient’s condition deteriorates. The critical transition to the pulseless cardiac arrest algorithm occurs when the heart rate falls below 60 bpm and is accompanied by signs of poor perfusion, despite adequate oxygenation and ventilation. This profound and refractory bradycardia is considered a pre-arrest condition because it cannot maintain sufficient cardiac output.
If the patient loses their pulse entirely, the transition to the cardiac arrest protocol must be immediate. This signifies that the heart is no longer generating detectable blood flow. Chest compressions must begin immediately to artificially circulate blood, initiating the high-quality cardiopulmonary resuscitation phase of the pulseless arrest algorithm. The focus shifts from supporting a failing heart to replacing its function manually.