How can I increase the PO2 in a child on a ventilator with a current PO2 of 68 mmHg?

Improving PO2 in a Child on Mechanical Ventilation

To increase the PO2 in this child, you should increase PEEP to 8-10 cmH2O while maintaining appropriate plateau pressures and considering recruitment maneuvers. 1

Assessment of Current Ventilator Settings

The current ventilator settings show:

• TV: 230 ml
• I:E ratio: 1:2
• RR: 14
• PEEP: 5 cmH2O
• FiO2: 100%
• T insp rise: 5%
• PO2: 68 mmHg (hypoxemia despite maximum FiO2)

Step-by-Step Approach to Improve Oxygenation

1. Optimize PEEP

• Increase PEEP from 5 to 8-10 cmH2O
• According to the Paediatric Mechanical Ventilation Consensus Conference (PEMVECC), higher PEEP is necessary based on underlying disease severity 1
• Titrate PEEP carefully while monitoring hemodynamics and plateau pressure
• Consider PEEP titration and lung recruitment maneuvers 1

2. Adjust I:E Ratio

• Consider increasing inspiratory time (decreasing I:E ratio from 1:2 to 1:1.5) to improve mean airway pressure and alveolar recruitment
• Set inspiratory time according to respiratory system mechanics and underlying disease 1

3. Consider Recruitment Maneuvers

• Perform lung recruitment maneuvers to open collapsed alveoli
• This should be done cautiously with careful monitoring of hemodynamics
• Use PEEP titration after recruitment to maintain open alveoli 1

4. Adjust Patient Position

• Ensure head of bed is elevated 30-45° 1, 2
• Consider prone positioning if severe hypoxemia persists despite other interventions 2

5. Check for Mechanical Issues

• Verify endotracheal tube position
• Use cuffed endotracheal tube with appropriate cuff pressure (≤20 cmH2O) 1
• Check for circuit leaks or disconnections
• Minimize dead space by removing unnecessary components 1

6. Consider Advanced Modes

• If conventional ventilation fails to improve oxygenation, consider high-frequency oscillatory ventilation (HFOV) 1, 3
• Combined high-frequency jet ventilation has shown benefit in children with severe respiratory failure, improving PaO2 while allowing lower peak pressures 3

7. Consider Inhaled Nitric Oxide

• If pulmonary hypertension is suspected, inhaled nitric oxide may improve oxygenation by selectively dilating pulmonary vessels in better ventilated areas 4
• Note that nitric oxide is primarily indicated for term and near-term neonates with hypoxic respiratory failure associated with pulmonary hypertension 4

Monitoring Parameters

• Continuously monitor SpO2 and end-tidal CO2 1
• Obtain arterial blood gases after each significant change in ventilator settings
• Monitor plateau pressure (keep ≤28 cmH2O) and driving pressure (keep <15 cmH2O) 1, 2
• Watch for signs of barotrauma or hemodynamic compromise
• Monitor pressure-time and flow-time scalars 1

Oxygenation Targets

• For PARDS (Pediatric Acute Respiratory Distress Syndrome):
  • SpO2 92-97% when PEEP <10 cmH2O
  • SpO2 88-92% when PEEP ≥10 cmH2O 1, 2
• Target PaO2 70-90 mmHg 2

Common Pitfalls to Avoid

1. Excessive PEEP: While increasing PEEP can improve oxygenation, excessive PEEP (>10-12 cmH2O) may lead to overdistension, increased mechanical power, and driving pressure in children with mild-moderate PARDS 5

2. High Respiratory Rate Strategy: Increasing respiratory rate to 30 breaths/min may not improve CO2 clearance and can produce dynamic hyperinflation and impair right ventricular ejection 6

3. Ignoring Hemodynamics: High PEEP can impair venous return and cardiac output, especially in patients with vasodilation 2

4. Inadequate Monitoring: Transcutaneous PO2 monitoring can be valuable for continuous assessment of oxygenation status rather than relying solely on intermittent blood gases 7

5. Overlooking Ventilator Synchrony: Target patient-ventilator synchrony to optimize gas exchange 1