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Global and Regional Tidal Volume Distribution in Spontaneously Breathing Mechanically Ventilated Children
Jefta van Dijk1, Alette A Koopman2, Robert Gt Blokpoel2
1Department of Paediatrics, Division of Paediatric Critical Care Medicine, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands. j.van.dijk01@umcg.nl.
Insights
Allowing ventilated children to breathe spontaneously in the recovery phase of acute respiratory failure did not negatively impact tidal volume distribution or end-expiratory lung volume. This supports continuous spontaneous ventilation modes for pediatric patients.
Area of Science:
- Pediatric critical care medicine
- Respiratory physiology
- Mechanical ventilation
Background:
- Spontaneous breathing in ventilated adults may improve lung mechanics.
- Effects of spontaneous breathing on lung mechanics in children are not well-studied.
- Investigating ventilatory support levels in pediatric acute respiratory failure is crucial.
Purpose of the Study:
- To explore the effect of ventilatory support levels on tidal volume (VT) distribution and end-expiratory lung volume (EELV) in spontaneously breathing ventilated children.
- To assess VT distribution and EELV in children during the recovery phase of acute respiratory failure.
Main Methods:
- Secondary analysis of a prospective clinical trial in children (< 5 years) comparing CPAP + PSV and PC/IMV + PSV.
- Electrical impedance tomography (EIT) used to assess VT distribution (center of ventilation) and EELV.
- Measurements taken during different ventilator modes and downward titration of pressure support.
Main Results:
- Thirty-five children (median age 4.5 months) were studied.
- No significant difference in VT distribution (coefficient of variation) between CPAP/PSV and PC/IMV + PSV.
- Downtapering pressure support significantly shifted VT distribution toward dependent lung regions.
Conclusions:
- Continuous spontaneous ventilation modes in children recovering from acute respiratory failure do not negatively affect VT distribution or EELV.
- Findings support the use of spontaneous breathing in ventilated pediatric patients.
- Further research on optimizing ventilatory support levels in children is warranted.
Background:
Allowing the ventilated adult patient to breathe spontaneously may improve tidal volume (VT) distribution toward the dependent lung regions, reduce shunt fraction, and decrease dead space. It has not been studied if these effects under various levels of ventilatory support also occur in children. We sought to explore the effect of level of ventilatory support on VT distribution and end-expiratory lung volume (EELV) in spontaneously breathing ventilated children in the recovery phase of their acute respiratory failure.
Methods:
This is a secondary analysis of data from a prospective clinical trial comparing 2 different ventilator modes during weaning in mechanically ventilated children < 5 y: CPAP + pressure support ventilation (PSV) and pressure control (PC)/intermittent mandatory ventilation (IMV) + PSV with the mandatory breath rate set at 25% of baseline. Using electrical impedance tomography (EIT), we assessed VT distribution by calculating the center of ventilation. Polynomial functions of the second degree were plotted to evaluate regional lung filling characteristics. Changes in end-expiratory impedance were calculated to assess changes in EELV. Baseline measurements were compared with measurements during CPAP/PSV, PC/IMV + PSV, and during a downward titration of the level of pressure support.
Results:
Thirty-five subjects with a median age 4.5 (2.1-12.9) months and a median ventilation time of 4.9 (3.3-6.9) d were studied. The overall median coefficient of variation was 50.1% and not different between CPAP/PSV or PC/synchronized IMV + PSV. Regional filling characteristics of the lung identified a homogeneous VT distribution under all study conditions. Downtapering of the level of PSV resulted in a significant shift of the coefficient of variation toward the dependent lung regions.
Conclusions:
Our data showed that allowing ventilated children in the recovery phase of respiratory failure to breathe spontaneously in a continuous spontaneous ventilation mode did not negatively affect VT distribution or EELV.
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