(112) PrEDICT Study: Premature Infant Electrical aCtivity of the DIaphragm (EDI) over Time

Background: Invasive Mechanical Ventilation (IMV) for respiratory failure is common in the Neonatal Intensive Care Unit (NICU) and can cause ventilator-induced diaphragmatic dysfunction. Optimizing settings is critical yet challenging. Neurally Adjusted Ventilatory Assist (NAVA) measures electrical diaphragmatic activity (Edi): Edi peak reflects maximal inspiratory effort, and Edi min reflects baseline diaphragmatic tone. These may guide ventilatory support even on non-NAVA modes. However, Edi reference levels for invasively ventilated infants across gestational ages (GA) are limited in the literature. We hypothesize that establishing reference values for Edi levels across GAs will enhance the clinical utility of Edi monitoring in invasively ventilated infants.

Objectives: To describe the longitudinal trends of Edi levels across GA and to develop normative reference values for invasively ventilated preterm infants.

Design/Methods: This is a prospective, non-randomized observational study of preterm infants born between 22 and 36 6/7 weeks GA admitted to the Level IV NICU at Children’s Wisconsin starting January 2024. Eligible infants were on IMV via Servo-U ventilator, had spontaneous respiratory efforts, and were nasogastric tube-dependent. Edi levels were collected longitudinally until 40 weeks corrected GA or 72 hours after discontinuing IMV. The raw Edi values were collected on minute-by-minute basis and have been aggregated into daily or weekly medians for analysis. A generalized linear mixed model using maximum likelihood estimation and compound symmetry covariance structure was used to assess the change of the key Edi measurements over time. A two-sided p-value < 0.05 were used as the term of statistical significance.

Results: 14 infants (43% male) contributed to this interim analysis. The median corrected GA was 31.9 weeks (IQR: 27.4-33.1), and the median birth weight was 632.57 g (IQR: 580.0-735.0). The median of Edi peak was 8.86 µV (IQR: 7.12–11.36), with no statistically significant change over time (p=0.23). In contrast, the median Edi min was 2.04 µV (IQR: 1.54–2.33) and the increase of Edi min over time was statistically significant (p=0.015) .

Conclusions: While Edi peak remains stable during IMV, the baseline diaphragmatic activity (Edi min) increases significantly with maturation. Edi min may serve as a sensitive physiologic marker to guide weaning strategies and predict extubation readiness in preterm infants. Further enrollment is ongoing to refine these reference values.