Longitudinal PEEP Responses Differ Between Children With ARDS and at Risk for ARDS

Area of Science:

• Pediatric Critical Care Medicine
• Respiratory Physiology
• Mechanical Ventilation

Background:

• Lung mechanics in pediatric patients with Acute Respiratory Distress Syndrome (ARDS) versus those at risk remain unclear.
• Investigating differences in end-expiratory lung volume (EELV), respiratory system compliance (C_RS), lung stress, and strain is crucial for optimizing ventilation strategies.

Purpose of the Study:

• To compare lung mechanics between pediatric patients with ARDS and those at risk for ARDS.
• To test the hypothesis that patients at risk for ARDS have higher EELV or C_RS and lower lung stress or strain during mechanical ventilation.

Main Methods:

• Longitudinal measurements of EELV, C_RS, strain, and stress were performed in 32 mechanically ventilated children.
• Subjects were categorized into ARDS (n=15) and at-risk (n=17) groups based on PALICC criteria.
• Incremental positive end-expiratory pressure (PEEP) trials were conducted, and measurements were taken at various time points.

Main Results:

• Subjects with ARDS exhibited lower C_RS and EELV, and higher strain and stress compared to the at-risk group longitudinally.
• EELV correlated positively with strain and stress in both groups.
• C_RS correlated with strain only in the at-risk group.
• Strain and stress levels remained within safe limits in both groups at PEEP levels of 4 or 10 cm H₂O.

Conclusions:

• Pediatric patients with ARDS demonstrate distinct lung mechanics compared to those at risk, characterized by reduced C_RS and EELV and increased strain and stress.
• Lung mechanics parameters varied over time and with different PEEP levels.
• Observed strain and stress were maintained within safe limits, suggesting potential for protective ventilation strategies.