What are the initial ventilator settings and modes for neonates requiring ventilation support?

Ventilator Modes and Graphs in Neonates: A Comprehensive Guide

For neonates requiring ventilatory support, initial ventilation should begin with Continuous Positive Airway Pressure (CPAP) for spontaneously breathing preterm infants with respiratory distress, while positive pressure ventilation (PPV) should be initiated with room air (21% oxygen) for term infants and 21-30% oxygen for preterm infants who are apneic or have a heart rate <100 beats per minute. 1, 2

Initial Ventilator Settings

Oxygen Concentration

• Term and late-preterm infants (≥35 weeks): Start with 21% oxygen (room air) 2
• Preterm infants (<35 weeks): Start with 21-30% oxygen 1, 2
• Titrate oxygen to achieve target preductal SpO₂:
  • 60-65% at 1 min
  • 65-70% at 2 min
  • 70-75% at 3 min
  • 75-80% at 4 min
  • 80-85% at 5 min
  • 85-95% at 10 min 2
• If bradycardia (HR <60/min) persists after 90 seconds of resuscitation with lower oxygen concentration, increase to 100% until heart rate recovers 1, 2

Pressure Settings

• Initial inflation pressure: 20 cm H₂O 1, 2
• May require 30-40 cm H₂O in some term babies without spontaneous ventilation 1
• PEEP: 5 cm H₂O (especially for preterm infants) 1, 2
• Ventilation rate: 40-60 breaths per minute 1, 2

Primary Ventilation Modes

1. Continuous Positive Airway Pressure (CPAP)

• Indications: Spontaneously breathing preterm infants with respiratory distress 1
• Benefits:
  • Decreases rate of intubation in delivery room
  • Reduces duration of mechanical ventilation
  • Potential reduction in death and/or bronchopulmonary dysplasia 1
  • Maintains functional residual capacity
• Pressure range: 5-8 cm H₂O
• Monitoring: Observe for chest movement, improvement in heart rate, and oxygen saturation 2

2. Positive Pressure Ventilation (PPV)

• Indications: Apnea, gasping, or heart rate <100/min after initial steps 1
• Delivery methods:
  • Flow-inflating bag
  • Self-inflating bag (note: cannot deliver PEEP without special valve)
  • T-piece resuscitator (provides more consistent pressures) 1
• Assessment: Primary measure of adequate ventilation is prompt improvement in heart rate 1, 2

3. Synchronized Intermittent Mandatory Ventilation (SIMV)

• Allows spontaneous breathing between mandatory breaths
• Reduces work of breathing compared to conventional mandatory ventilation 3, 4
• Particularly useful during weaning phase

4. Volume-Targeted Ventilation

• Delivers consistent tidal volumes (4-6 mL/kg) despite changes in lung compliance
• May provide better lung protection than traditional pressure control modes 3
• Reduces risk of volutrauma and barotrauma

5. High-Frequency Ventilation

• Uses very small tidal volumes at rapid rates (>150 breaths/min)
• Types include:
  • High-Frequency Oscillatory Ventilation (HFOV)
  • High-Frequency Jet Ventilation (HFJV)
• May be beneficial for air leak syndromes or severe respiratory failure 3

Advanced Ventilation Strategies

Non-Invasive Ventilation Options

• Nasal Intermittent Positive Pressure Ventilation (NIPPV):

  • May be more efficacious than CPAP in the post-extubation phase 5
  • Shows lower lung inflammation markers compared to CPAP in animal models 6

• Non-Invasive High-Frequency Oscillatory Ventilation (NHFOV):

  • Emerging option for babies requiring high constant distending pressure 5
  • Limited clinical outcome data but preliminary studies suggest safety 5

Invasive Ventilation Considerations

• Neurally Adjusted Ventilatory Assist (NAVA):
  • Uses electrical activity of diaphragm to trigger and cycle ventilator breaths
  • Improves patient-ventilator synchrony 3
  • FDA approved for both invasive and non-invasive ventilation

Interpreting Ventilator Graphs

Flow-Time Waveforms

• Square waveform: Constant flow throughout inspiration
• Descending ramp: High initial flow that decreases during inspiration
• Sinusoidal: Smooth transition between inspiration and expiration

Pressure-Time Waveforms

• Shows pressure changes during respiratory cycle
• Helps identify:
  • Patient-ventilator asynchrony
  • Auto-PEEP
  • Inadequate inspiratory time

Volume-Time Waveforms

• Displays delivered tidal volume
• Helps identify:
  • Leaks around endotracheal tube
  • Changes in compliance
  • Adequacy of tidal volume

Monitoring and Troubleshooting

Key Monitoring Parameters

• Heart rate (primary indicator of successful ventilation) 2
• Oxygen saturation via pulse oximetry
• End-tidal CO₂ (confirms proper endotracheal tube placement) 1
• Chest movement
• Blood gases

Common Ventilation Problems

• Inadequate oxygenation: Check FiO₂, PEEP, mean airway pressure
• Inadequate ventilation: Check rate, tidal volume, inspiratory time
• Air leaks: Check for pneumothorax if sudden deterioration occurs
• Tube displacement: Confirm position with exhaled CO₂ detection 1

Special Considerations for Preterm Infants

• Higher risk of lung injury from mechanical ventilation
• Consider early use of CPAP rather than immediate intubation 1
• Use volume-targeted ventilation when possible to reduce volutrauma 3
• Lower tidal volumes (4-6 mL/kg) to minimize lung injury 3
• Consider surfactant administration via INSURE technique (Intubation-Surfactant-Extubation) 6

Weaning Strategies

• Gradual reduction in ventilatory support based on:
  • Blood gas values
  • Clinical assessment
  • Work of breathing
• Consider extubation to non-invasive support when minimal ventilator settings are reached
• Note that weaning is not a realistic goal for certain conditions like Congenital Central Hypoventilation Syndrome 1

Remember that the primary goal of ventilation in neonates is to maintain adequate gas exchange while minimizing ventilator-induced lung injury, which is crucial for reducing mortality and improving long-term outcomes.