6.3 PALS Assessment, CPR & Cardiac Arrest

6.3 PALS Assessment, CPR & Cardiac Arrest

Pediatric cardiac arrest commonly follows progressive respiratory failure or shock, although primary arrhythmia, congenital heart disease, myocarditis, trauma, toxins, and sudden collapse also occur. The American Heart Association (AHA) Pediatric Advanced Life Support (PALS) guidelines emphasize early recognition, rapid physiologic stabilization, high-quality cardiopulmonary resuscitation (CPR), and prompt reversal of hypoxemia and acidosis before irreversible ischemic arrest occurs.

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PALS Systematic Approach: Evaluate, Identify, Intervene

The PALS framework consists of a continuous, iterative cycle: Evaluate $\rightarrow$ Identify $\rightarrow$ Intervene.

[Initial Assessment: Pediatric Assessment Triangle (PAT)]
   Appearance | Work of Breathing | Circulation to Skin
                     │
                     ▼
[Primary Assessment: ABCDE Sequence]
   Airway | Breathing | Circulation | Disability | Exposure
                     │
                     ▼
[Secondary Assessment & Diagnostics]
   Focused SAMPLE History & Targeted Lab/Radiographic Studies

1. Pediatric Assessment Triangle (PAT)

A rapid 30-second observational assessment conducted without touching the child:

• Appearance: Tone, interactiveness, consolability, look/gaze, speech/cry (reflects central nervous system oxygenation and perfusion).
• Work of Breathing: Tachypnea, retractions, nasal flaring, head bobbing, grunting, stridor, wheezing.
• Circulation to Skin: Pallor, mottling, cyanosis, petechiae.

2. Primary Assessment (ABCDE)

• Airway: Patent, maintainable with simple positioning (sniffing position, jaw thrust), or unmaintainable (requires advanced airway).
• Breathing: Respiratory rate, air entry, chest expansion, breath sounds, $SpO_2$, transcutaneous or end-tidal $CO_2$.
• Circulation: Heart rate, central vs. peripheral pulses, capillary refill time ($<2\text{ seconds}$ is normal), skin temperature, systemic blood pressure.
  • Hypotension Thresholds by Age (Systolic BP):
    • Term Neonates (0–28 days): $<60\text{ mmHg}$
    • Infants (1–12 months): $<70\text{ mmHg}$
    • Children (1–10 years): $<70 + (2 \times \text{Age in years})\text{ mmHg}$
    • Children $>10$ years: $<90\text{ mmHg}$
• Disability: Neurological status using the AVPU scale (Alert, Voice, Pain, Unresponsive) or Glasgow Coma Scale (GCS), pupil size and reactivity, and bedside blood glucose (rule out hypoglycemia).
• Exposure: Undress patient to inspect for trauma, rashes, purpura fulminans (meningococcemia), and monitor core body temperature.

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Pediatric High-Quality CPR Metrics

High-quality CPR is the cornerstone of pediatric resuscitation, maximizing coronary and cerebral perfusion pressures.

Core CPR Performance Metrics

• Compression Rate: 100 to 120 compressions/min across all pediatric age groups.
• Compression Depth:
  • Infants (<1 year): At least one-third (1/3) the AP diameter of the chest, approximately 1.5 inches (4 cm).
  • Children (1 year to puberty): At least one-third (1/3) the AP diameter of the chest, approximately 2.0 inches (5 cm).
  • Adolescents: Adult depth of 2.0 to 2.4 inches (5 to 6 cm).
• Recoil: Allow full chest wall recoil after each compression; do not lean on the chest. Incomplete recoil increases intrathoracic pressure, impeding venous return and decreasing cardiac output.
• Minimize Interruptions: Keep pauses in compressions to < 10 seconds (e.g., for rhythm checks or defibrillation).
• Compression-to-Ventilation Ratios:
  • Single Rescuer: 30:2.
  • Two Healthcare Rescuers: 15:2.
  • Advanced Airway in Place (ETT or Supraglottic Airway): Deliver continuous chest compressions without pauses for breaths, providing 1 breath every 2 to 3 seconds (20 to 30 breaths/min).
  • Avoid Excessive Ventilation: Hyperventilation increases intrathoracic pressure, decreases venous return, reduces cardiac output, and induces cerebral vasoconstriction via hypocarbia.

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Pediatric Cardiac Arrest: Shockable vs. Non-Shockable Algorithms

When a pediatric patient has no central pulse or signs of life, CPR is initiated immediately and the monitor/defibrillator is attached to identify the cardiac rhythm.

Table 6.3.1: Pediatric Cardiac Arrest Management: Shockable vs. Non-Shockable

Defibrillation Sequence for VF / Pulseless VT

1. Deliver Shock 1 (2 J/kg) unsynchronized. Immediately resume CPR for 2 minutes without checking rhythm or pulse.
2. Rhythm check: If persistent VF/pVT, deliver Shock 2 (4 J/kg). Resume CPR immediately. Administer Epinephrine 0.01 mg/kg IV/IO and consider advanced airway placement.
3. Rhythm check: If persistent VF/pVT, deliver Shock 3 ($\ge 4\text{ J/kg}$, up to 10 J/kg). Resume CPR immediately. Administer Amiodarone 5 mg/kg IV/IO bolus (or Lidocaine 1 mg/kg).

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Pediatric Bradycardia with Cardiopulmonary Compromise

Bradycardia in children is most frequently caused by progressive tissue hypoxia, acidosis, and hypothermia.

The Critical Clinical Threshold: HR < 60 bpm

• If a child has a heart rate $<60\text{ beats/min}$ with signs of poor perfusion (altered mental status, weak central pulses, absent peripheral pulses, hypotension, delayed capillary refill) despite effective oxygenation and ventilation:
  • MANDATORY PALS INTERVENTION: INITIATE CHEST COMPRESSIONS IMMEDIATELY!
  • Major NBRC Testing Principle: Do not wait for complete asystole. In pediatrics, symptomatic bradycardia with hypoperfusion is treated as functional cardiac arrest.

Pharmacologic Interventions in Bradycardia

• Epinephrine (First-Line):
  • Dose: 0.01 mg/kg IV/IO ($0.1\text{ mL/kg}$ of 0.1 mg/mL formulation). Repeat every 3 to 5 minutes. Stimulates $\beta_1$-adrenergic receptors to increase chronotropy and inotropy, and $\alpha_1$-receptors to increase systemic vascular resistance.
• Atropine Sulfate:
  • Dose: 0.02 mg/kg IV/IO (minimum single dose 0.1 mg; maximum single dose 0.5 mg in children, 1.0 mg in adolescents). May repeat once.
  • Specific Indications: Reserved for bradycardia resulting from increased vagal tone (e.g., during laryngoscopy, suctioning, or carotid sinus stimulation), organophosphate toxicity, or primary atrioventricular (AV) conduction block.
  • NPS Exam Caution: Doses $<0.1\text{ mg}$ can precipitate paradoxical central vagal stimulation, worsening the bradycardia.
• Emergency Transthoracic / Transcutaneous Pacing: Indicated for bradycardia unresponsive to medical therapy due to congenital heart disease, surgical complete heart block, or intrinsic nodal pathology.

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