Partitioning of respiratory system resistance in children with respiratory insufficiency

Area of Science:

• Pediatric Pulmonology
• Respiratory Physiology
• Mechanical Ventilation

Background:

• Respiratory system resistance (Rrs) can be partitioned into flow-resistive (Rint) and viscoelastic/inhomogeneity (DeltaR) components using end-inspiratory airway occlusion.
• Understanding the flow and volume dependence of these components is crucial for optimizing mechanical ventilation in children.

Purpose of the Study:

• To investigate the flow and volume dependence of Rrs, Rint, and DeltaR in pediatric patients undergoing mechanical ventilation.
• To compare these parameters in children with and without primary lung disorders.

Main Methods:

• End-inspiratory airway occlusion was used to measure Rrs, Rint, and DeltaR in 13 children on mechanical ventilation.
• Subjects were divided into two groups: Group 1 (pulmonary insufficiency) and Group 2 (no primary lung disorder).
• Flow and volume dependence of Rrs, Rint, and DeltaR were analyzed under isovolume and isoflow conditions.

Main Results:

• DeltaR was elevated in most mechanically ventilated children, irrespective of primary lung disease.
• Rint was increased in lower airway obstruction and in most patients without primary lung disorder, but less so in parenchymal lung disease.
• DeltaR decreased with increasing flow and increased with increasing tidal volume, exhibiting opposite dependence compared to airway resistance.

Conclusions:

• The DeltaR component is significantly affected in pediatric patients on mechanical ventilation, indicating viscoelasticity and inhomogeneity.
• The distinct flow and volume dependencies of DeltaR suggest it reflects different pathophysiological mechanisms than Rint.
• These findings highlight the importance of assessing DeltaR for a comprehensive understanding of respiratory mechanics in ventilated children.