A55-20 Potential for Lung Recruitment and Peep Optimization Utilizing Electrical Impedance Tomography in Early Pediatric Acute Respiratory Distress Syndrome

Abstract Rationale In Pediatric Acute Respiratory Distress Syndrome (PARDS), the potential for lung recruitment and the optimal PEEP that balances overdistention and collapse is unknown. Objective 1. Determine the early potential for lung recruitment using recruitment-to-inflation (RI) ratio and cumulative collapse measured by Electrical Impedance Tomography (EIT). 2. Assess oxygenation and pulmonary mechanics following PEEP titration at the balance of overdistention and collapse informed by EIT. Methods Patients with early PARDS (PALICC criteria and intubated ≤ 72 hours) were identified. Baseline ventilator settings including pre-assessment PEEP set by the clinical team, were recorded. Airway opening pressure (AOP), R/I ratio and decremental PEEP steps with EIT recording were performed. Lung collapse and overdistension were derived by EIT. Crossing point PEEP (PEEPCP) was defined as the balance of minimal overdistention and collapse. High lung recruitability was defined in two ways: (1) R/I ratio 0.5 or (2) % collapse median value of the % collapse for all patients assessed by decremental PEEP from 20 cmH2O to 6 cmH2O (PEEP20-6). Respiratory system compliance and oxygenation were assessed at PEEPCP and compared to pre-assessment PEEP (PEEPclinical). Variables were analyzed as continuous or dichotomous; Parametric tests such as paired t-tests and Pearson correlation were used while non-parametric tests such as Mann-Whittney, Wilcoxon, or Spearman correlation tests were used when normality failed. Results Sixteen patients were enrolled (median age 9 years). Five patients exhibited an AOP with a median of 7 cmH2O (95% CI, 6-14). Eight patients were recruitable by R/I ratio compared to 5 that were not recruitable. Eight patients were found to be recruitable by EIT with a median value of 17.8% collapse (PEEP20-6). PEEPCP was not significantly different from PEEPclinical. Hyperdistention correlated inversely with R/I ratio (p = 0.04). PEEPCP positively correlated with R/I ratio (p = 0.04) (Fig 1) and percent collapse (PEEP20-6) (p 0.0001). PEEPCP was higher in recruitable vs non-recruitable (median of 13.5 cmH2O vs 9 cmH2O in (p = 0.0006)). At PEEPCP, driving pressure decreased (p = 0.0005), compliance increased (p = 0.03), oxygenation index (OI) decreased (p = 0.008), and PaO2/FiO2 (PF ratio) increased (p = 0.004) compared to the PEEPclinical. Conclusions Early PARDS exhibits heterogenous recruitability. Lower R/I aligned with overdistention at higher PEEP. EIT identified a higher PEEPCP in recruitable lungs. While PEEPCP did not differ significantly for the entire cohort, setting PEEP to PEEPCP improved mechanics and oxygenation. These data support the potential for individualized PEEP titration to balance overdistention and collapse in early PARDS. This abstract is funded by: None