EIT guided evaluation of regional ventilation distributions in neonatal and pediatric ARDS: a prospective feasibility study

Abstract

Background: Despite international guidelines for lung protective ventilation in neonatal or pediatric acute respiratory distress syndrome (nARDS/ pARDS), prospective data on bedside monitoring tools for regional ventilation distribution and lung mechanics are still rare. As a bedside and radiation-free procedure, electrical impedance tomography (EIT) offers a practical and safe approach for analyzing regional ventilation distributions. Recent trials in adults have shown the efficacy of an individualized EIT guided strategy for the improvement of ventilator induced lung injury (VILI).

Methods: We performed a single-center prospective feasibility study from November/2021 to December/2023 in the department of neonatal and pediatric intensive care medicine at the University Children´s Hospital in Bonn. All patients with diagnosis of nARDS (or history of perinatal lung disease-PLD)/ pARDS were screened for study inclusion. In all patients a decremental PEEP (positive end-expiratory pressure) trial was performed with a continuous EIT monitoring for an individual analysis of the EIT guided pixel compliance (C_EIT) and PEEP finding (EIT-PEEP). In the offline analysis, further EIT derived indices, such as global inhomogeneity index (GI), and center of ventilation (CoV), were calculated.

Results: Overall, 40 EIT measurements were performed in 26 neonatal and pediatric patients (nARDS/PLD, n = 6; and pARDS, n = 20) within a predefined decremental PEEP trial. Thirteen patients were classified as having severe nARDS (PLD)/ pARDS with an Oxygen Saturation Index (OSI) > 12 or Oxygenation Index (OI) > 16. In-hospital mortality rate was 27% in the overall cohort. The median EIT-PEEP (11mbar) was calculated as lowest, as compared to the clinically set PEEP (11.5mbar, p < 0.001), and the ARDSnetwork PEEP table recommendation (ARDSnet-PEEP, 14mbar, p = 0.018). In patients with nARDS/PLD, the EIT-PEEP was calculated 3mbar below the clinically set PEEP (p = 0.058) and 11 mbar below the ARDSnet-PEEP (p = 0.01). In the linear regression analysis, EIT-PEEP and the dynamic compliance (C_DYN) at -2mbar presented a significant correlation with a Cohen´s R² of 0.265 (β: 0.886, p = 0.005).

Conclusion: EIT is feasible and can be performed safely in patients with diagnosis of nARDS/PLD and pARDS, even during ongoing extracorporeal membrane oxygenation (ECMO) support. An individualized PEEP finding strategy according to the EIT compliance might optimize regional ventilation distribution in these patients and can potentially decrease VILI.

Clinical trial registration: The study was registered at the German Clinical Trials Register (GCT; trial number: DRKS 00034905, Registration Date 15.08.2024). The registration was performed retrospectively after inclusion of the last patient.

Keywords: Acute respiratory distress syndrome; Electrical impedance tomography; Neonatal; Pediatric; Regional ventilation.

Fig. 1

CONSORT flow-chart of the study population and patients admitted to our neonatal and pediatric intensive care unit with the diagnosis of nARDS/ history of PLD and pediatric ARDS. Patients with pARDS were referred to the ICD diagnosis J80.0 = acute respiratory distress syndrome (ARDS): between 28 days and 18 years [J80.0 [–9] = subgroups and severity of ARDS] and patients with neonatal respiratory failure were referred to the ICD diagnosis P28.5 = respiratory failure in neonates. Abbreviations: EIT: electrical impedance tomography; nARDS: neonatal acute respiratory distress syndrome; NICU: neonatal intensive care unit; pARDS: pediatric acute respiratory distress syndrome; PICU: pediatric intensive care unit: PLD: perinatal lung disease

Fig. 2

Blood gas analysis with paO₂- and paCO₂-measurements, as well as SpO₂-, SaO₂-, and dynamic compliance measurements during the decremental PEEP titration. Abbreviations: BGA: blood gas analysis; paO₂: partial arterial pressure of oxygen; paCO₂: partial arterial pressure of carbon dioxide; SaO₂: arterial oxygen saturation; SpO₂: pulse-oxymetric oxygen saturation

Fig. 3

Compliance loss due to overdistension (OD, blue line) and lung collapse (LC, green line) during the decremental PEEP titration for the overall cohort (A), for subgroup A (pARDS) (B), and subgroup B (nARDS/PLD). The crossing-point between both lines with the lowest estimated lung overdistension and lung collapse according to the EIT pixel compliance (Costa et al.) represents the optimal EIT based PEEP level. Abbreviations: nARDS: neonatal acute respiratory distress syndrome, pARDS: pediatric acute respiratory distress syndrome, PLD: perinatal lung disease

Fig. 4

The horizontal and vertical Center of Ventilation (CoV_X, CoV_Y,A and B), and the Global Inhomogeneity Index (GI, C) for the respective subgroups (nARDS/PLD vs. pARDS) during the decremental PEEP titration are displayed. The asterisk is illustrating a p-value < 0.05 when comparing the respective value with the value calculated at PEEP level + 4mbar. Abbreviations: nARDS: neonatal acute respiratory distress syndrome, pARDS: pediatric acute respiratory distress syndrome, PLD: perinatal lung disease

Fig. 5

The ventilated lung area (bars are presented with 95% CI), separated into 4 regions of interest (ventral, mid-ventral, mid-dorsal, dorsal) during the PEEP titration maneuver. Abbreviations: BL: baseline

Fig. 6

Calculation of the median values for the clinically set PEEP, the EIT-PEEP, and the ARDSnet-PEEP in the overall cohort (A), for the respective subgroups (B), and according to patient’s outcome (C). The asterisk is illustrating a p-level < 0.05 for comparison of EIT-PEEP compared to the clinically set PEEP (A) or comparison between subgroups (B and C). Abbreviations: nARDS: neonatal acute respiratory distress syndrome, pARDS: pediatric acute respiratory distress syndrome, PLD: perinatal lung disease