What is the best initial ventilation strategy for a pediatric patient with severe hypoxemia and bilateral chest infiltration on chest x-ray, who is mechanically intubated and receiving 100% FiO2 (fraction of inspired oxygen)?

Ventilation Strategy for Pediatric Severe Hypoxemia with Bilateral Infiltrates

Use low tidal volume ventilation (6 mL/kg predicted body weight) with adequate PEEP, and accept permissive hypercapnia—this is the lung-protective strategy that reduces mortality in severe hypoxemic respiratory failure with bilateral infiltrates, which represents pediatric ARDS. 1

Immediate Ventilator Settings

Low tidal volume ventilation is mandatory:

• Set tidal volume at 6 mL/kg predicted body weight (not actual body weight) 1
• Maintain plateau pressure <30 cmH2O, ideally <28 cmH2O 1, 2
• This lung-protective approach reduces ventilator-induced lung injury and improves survival 3, 1

PEEP strategy based on severity:

• For moderate-to-severe hypoxemia (which this patient has, given 100% FiO2 failure), use higher PEEP strategy of 10-15 cmH2O 1
• PEEP prevents alveolar collapse and maintains lung recruitment 1
• The statement "no PEEP to prevent barotrauma" (option C) is incorrect—PEEP is protective, not harmful, when combined with low tidal volumes 1

Permissive hypercapnia is acceptable:

• Allow PaCO2 to rise while maintaining arterial pH >7.20 1, 4
• Do not increase tidal volume to "clear CO2" (option B is wrong)—this increases mortality by causing ventilator-induced lung injury 4
• After ROSC or in critical illness, target normocapnia (PaCO2 35-45 mmHg) when possible, but prioritize lung protection over normal CO2 3

Why High Tidal Volume is Dangerous

Never use tidal volumes >8 mL/kg predicted body weight, even if hypercapnia develops:

• High tidal volumes cause overdistension and ventilator-induced lung injury 1, 4
• This increases mortality in ARDS patients 4
• The ARDSNet trial demonstrated survival advantage with 6 mL/kg versus 12 mL/kg tidal volumes 3

Oxygenation Management

Titrate FiO2 downward once oxygenation improves:

• Target SpO2 92-97% or 94-99% in pediatrics 3, 1
• Avoid prolonged exposure to 100% FiO2—wean as soon as possible 3
• Both hyperoxia (PaO2 >300 mmHg) and hypoxemia (PaO2 <60 mmHg) increase mortality 3

Rescue Therapies if Conventional Ventilation Fails

Consider these interventions in sequence:

• High-frequency oscillatory ventilation (HFOV) may be considered as rescue therapy when conventional ventilation fails, using an open lung strategy 3, 2
• Prone positioning for 12-16 hours daily if PaO2/FiO2 remains <150 despite optimization 1, 4
• Inhaled nitric oxide (20 ppm) can improve oxygenation in pediatric hypoxemic respiratory failure with pulmonary hypertension 5
• ECMO for refractory hypoxemia if available and disease is reversible 2, 4

Critical Pitfall to Avoid

The most dangerous error is using high tidal volumes (option B) to normalize CO2:

• This directly contradicts lung-protective ventilation principles 1, 4
• Permissive hypercapnia with low tidal volumes saves lives; attempting to normalize CO2 with high tidal volumes kills patients 3, 1
• In pediatric post-cardiac arrest care, both hypocapnia (PaCO2 <30 mmHg) and hypercapnia (PaCO2 >50 mmHg) are associated with mortality, but lung protection takes priority 3

Answer: Option A (Low tidal volume with permissive hypercapnia) is correct.