Mechanical Ventilation in Children

Indications & Goals - Breathless Kiddos SOS

• Indications (Why ventilate?):
  • Respiratory Failure:
    • Hypoxemic: e.g., ARDS, pneumonia ($PaO_2/FiO_2 < \textbf{200}$)
    • Hypercapnic: e.g., severe asthma, NMD ($PaCO_2 > \textbf{55}$ mmHg, pH < 7.25)
  • Airway Protection: GCS < 8, risk of aspiration
  • Apnea: Central or prolonged obstructive
  • ↑ Work of Breathing: Impending fatigue, respiratory muscle exhaustion
  • Cardiopulmonary Arrest
• Goals (What to achieve?):
  • Improve Gas Exchange: Target $SpO_2 > \textbf{92}%$, acceptable $PaCO_2$
  • ↓ Work of Breathing: Patient comfort, prevent muscle fatigue
  • Lung Protection: Minimize Ventilator-Induced Lung Injury (VILI)
  • Supportive Care: Allow recovery from underlying pathology

⭐ In children, respiratory distress progressing to failure is a more common pathway to cardiac arrest than primary cardiac events.

Initiation & Modes - Tiny Lungs, Big Help

• Initiation:
  • Secure airway: ETT $(Age/4)+4$ uncuffed, $(Age/4)+3.5$ cuffed. Confirm.
  • Initial Vt: 4-8 mL/kg (IBW).
  • PEEP: 3-5 cm H₂O.
  • FiO₂: Start 100%, titrate for SpO₂ >92%.
  • RR & Ti: Age-dependent.
• Common Modes:
  • VC: Set Vt.
  • PC: Set PIP; Vt varies. Good for stiff lungs.
  • PSV: Spontaneous breaths; for weaning.
  • HFOV: Severe ARDS.

⭐ Lung Protective Strategy (LPS): Low Vt (4-6 mL/kg PBW), Pplat <28-30 cm H₂O.

Key Parameters & Settings - Numbers Game For Lungs

• Tidal Volume (Vt): 6-8 mL/kg (ideal body weight); ARDS: 4-6 mL/kg.
• PEEP: Initial 5 cm H₂O; titrate for oxygenation & hemodynamics.
• Respiratory Rate (RR): Age-specific:
  • Infant: 25-40/min
  • Child: 20-30/min
  • Adolescent: 12-20/min
• Inspiratory Time (Ti): Infants 0.3-0.7s; Children 0.5-1.0s. I:E ratio 1:2 - 1:3.
• FiO₂: Start 100% if hypoxic; titrate to maintain SpO₂ >92-94%.
• Pressures:
  • Peak Inspiratory Pressure (PIP): Keep <30-35 cm H₂O (ARDS <28).
  • Plateau Pressure (Pplat): Keep <28-30 cm H₂O (ARDS <25).
  • Driving Pressure ($P_{driving}$ = Pplat - PEEP): Target <15 cm H₂O.

⭐ Driving pressure ($P_{driving}$ = Pplat - PEEP) <15 cm H₂O is associated with improved survival in ARDS patients, including children.

Monitoring & Weaning - Freedom Breath Quest

• Monitoring: Clinical (RR, WOB, effort), $SpO_2$ (>92%), ABG ($PaCO_2$ 35-45 mmHg), EtCO2, ventilator waveforms & mechanics.
• Weaning Readiness (📌 ROAM criteria):
  • Resolution/Improvement of illness.
  • Oxygenation: $PaO_2/FiO_2 > \textbf{150-200}$, PEEP $\le \textbf{5-8}$ cm H2O, $FiO_2 \le \textbf{0.4}$.
  • Awake, alert, adequate cough.
  • Minimal sedation/vasopressors.
• SBT: Low PSV (5-7 cm H2O)/CPAP (5 cm H2O) for 30 min-2 hrs. Success if stable vitals, no distress. Then extubate.

⭐ Successful Spontaneous Breathing Trial (SBT) is the most reliable indicator for extubation readiness.

Complications & Special Cases - Tricky Breaths

• Barotrauma/Volutrauma: Pneumothorax, PIE. Prevent with low $V_T$, $P_{plat}$ <30 cmH2O.
• VAP: ↑ Risk with duration. Prevention bundles.
• Oxygen Toxicity: Use lowest FiO2 for $SpO_2$ >92%.
• Auto-PEEP: Esp. in asthma. ↑ $T_E$, ↓ RR.
• ARDS: LPS: $V_T$ 4-6 mL/kg PBW, PEEP guided by $SpO_2$/FiO2.

⭐ In pediatric ARDS, target $P_{plat}$ ≤28-30 cmH2O; higher PEEP may be needed.

• Asthma: Permissive hypercapnia, avoid breath stacking. oka

High‑Yield Points - ⚡ Biggest Takeaways

• Target tidal volume (Vt) is 6-8 mL/kg of ideal body weight (IBW).
• Initial PEEP is typically 5 cm H2O; titrate for oxygenation and hemodynamics.
• Employ lung protective strategies: low Vt, appropriate PEEP, and limit plateau pressure (Pplat) <28-30 cm H2O.
• Permissive hypercapnia (PaCO2 ↑) is acceptable in ARDS if pH remains >7.20-7.25.
• Cuffed endotracheal tubes are increasingly preferred for precise ventilation and aspiration prevention.
• Key complications include Ventilator-Associated Pneumonia (VAP), barotrauma, and volutrauma.
• Spontaneous Breathing Trials (SBTs) are crucial for assessing readiness for extubation.