Ventilator Settings for Weaning a 1-Month-Old Child from SIMV Volume Control

Introduction to Ventilator Settings

• The American Thoracic Society recommends setting the inspiratory trigger at 0.5-0.6 L/min, expiratory trigger at 15-25% of peak inspiratory flow, PS rise time at 0.1-0.2 seconds, and bias flow at 4-6 L/min to optimize patient-ventilator synchrony and facilitate successful extubation in 1-month-old children 1, 2

Inspiratory Trigger

• Set the inspiratory trigger sensitivity at 0.5-0.6 L/min for infants to optimize patient-ventilator synchrony while avoiding auto-triggering 2
• The trigger should be sensitive enough to detect the infant's inspiratory effort but not so sensitive that it auto-triggers from circuit movement or cardiac oscillations 1
• Measure flow near the Y-piece of the patient circuit for children <10 kg to improve trigger sensitivity 1, 3

Expiratory Trigger

• Set the expiratory trigger at 15-25% of peak inspiratory flow for infants to prevent premature cycling and optimize synchrony 2
• Monitor the flow-time scalar to ensure proper cycling from inspiration to expiration 1, 4
• Adjust expiratory trigger based on observation of flow-time waveforms to prevent air-trapping, especially important in this age group 4

Pressure Support Rise Time

• Set PS rise time at 0.1-0.2 seconds for infants to provide smooth pressure delivery without causing flow starvation 2
• Too fast rise time may cause pressure overshooting and patient discomfort 1

Bias Flow

• Set bias flow at 4-6 L/min for infants to ensure adequate flow availability for triggering without increasing work of breathing 1, 2
• Excessive bias flow can increase dead space ventilation and work of breathing 1

Weaning Strategy

• Target patient-ventilator synchrony as a primary goal during weaning 1, 2
• Start weaning as soon as possible and perform daily extubation readiness testing 1, 5
• Monitor pressure-time and flow-time scalars to assess patient-ventilator interaction 1, 4

Monitoring Parameters During Weaning

• Measure SpO2 continuously and maintain ≥95% in healthy lungs 1, 2
• Monitor end-tidal CO2 in all ventilated children 1
• Target PCO2 of 35-45 mmHg for healthy lungs, with higher values acceptable during weaning if pH >7.20 1, 2

Common Pitfalls to Avoid

• Setting inspiratory trigger too sensitive or too insensitive can increase work of breathing or cause auto-triggering 1
• Inappropriate expiratory trigger settings can lead to air-trapping or premature cycling 4
• Weaning too rapidly can lead to fatigue and extubation failure 1, 5
• Failure to monitor for patient-ventilator asynchrony can increase work of breathing 1, 2