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

Publication Number: 4699.715

Kaung Myat, Medical College of Wisconsin, Wauwatosa, WI, United States; Da'Jhnae Gambrell-Sanders, Medical College of Wisconsin, Milwaukee, WI, United States; Liyun Zhang, Medical College of Wisconsin, Milwaukee, WI, United States; Ke Yan, Medical College of Wisconsin, Milwaukee, WI, United States; Jennifer Nitschke-Thomas, Children's Hospital of Wisconsin, Milwaukee, WI, United States; Erwin T. Cabacungan, Medical College of Wisconsin, Children's Wisconsin, Milwaukee, WI, United States; Vijender R. Karody, Medical College of Wisconsin, Milwaukee, WI, United States; Jennifer Henningfeld, Medical College of Wisconsin, Milwaukee, WI, United States

Background: Invasive Mechanical Ventilation (IMV) for respiratory failure is common in the Neonatal Intensive Care Unit (NICU) and can cause ventilator-induced diaphragmatic dysfunction. Neurally Adjusted Ventilatory Assist (NAVA) measures electrical diaphragmatic activity (Edi): Edi peak reflects maximal inspiratory effort, and Edi min reflects baseline diaphragmatic tone. Edi reference levels for invasively ventilated infants across gestational ages (GA) are lacking. We hypothesize that establishing reference values for Edi levels across GAs will enhance clinical utility of Edi monitoring in invasively ventilated infants.

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

Design/Methods: This is a prospective observational IRB-approved study of preterm infants born between 22 and 36 6/7 weeks GA admitted to a Level IV NICU starting January 2024. Eligible infants were on IMV via Servo-U ventilator, had spontaneous respiratory efforts, and nasogastric tube-dependent. Edi levels were collected longitudinally until 40 weeks corrected GA or 72 hours after discontinuing IMV. 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 key Edi measurements over time.

Results: 24 infants were enrolled. The median corrected GA was 30.6 weeks (IQR: 28.4,32.1) and median birth weight was 685.0 g (IQR: 597.5, 798.0) (Table 1). The median Edi peak was 8.62 µV (IQR: 7.54, 10.13) with no statistically significant change over time (p=0.19) (Fig 1.1). In contrast, the median Edi min was 2.17 µV (IQR: 1.61, 2.42) with no statistically significant change over time (p=0.06) (Fig 1.2).
When both Edi peak and min were categorized based on three different GAs, only Edi min increased with advancing GA. Edi min was significantly different between the GAs of < 27w6d and 28 to 31w6d (p=0.044) (Fig 2).

Conclusion(s): In invasively ventilated premature infants, Edi peak remained stable across GAs while Edi min increased with maturation. Our results suggest that in the most immature infants, improving Edi min reflects their maturing neural-respiratory drive and tonic diaphragmatic activity. Edi peak stability across GAs may be due to the ventilator providing inspiratory assistance, allowing consistent neural drive. Edi min may serve as a sensitive physiologic marker to guide weaning strategies and predict extubation readiness in preterm infants.

Table 1. Characteristics of Infants


Fig 1.1 Weekly Median Edi peak Trajectories and Fig 1.2 Weekly Median Edi min Trajectories
The x-axis represents gestational age in weeks and y-axis represents median Edi peak and min in µV respectively.

Fig 2. Media Edi peak and min in different GA Groups
The x-axis represents median Edi peak and min respectively in µV and y-axis represents gestational age groups.