779 - An Examination of High Frequency Oscillatory Ventilation and its Impact on Respiratory Outcomes in Extremely Low Gestational Age Infants: A Retrospective Analysis

Publication Number: 2760.779

Averie V. DePalma, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada; Tanvi Ahluwalia, University of Ottawa Faculty of Medicine, Ottawa, ON, Canada; Anne Tsampalieros, CHEO Research Institute, Ottawa, ON, Canada; Nick Barrowman, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada; Brigitte Lemyre, University of Ottawa Faculty of Medicine, Ottawa, ON, Canada

Background: The survival of extremely low gestational age (ELGA) infants, those born < 26 weeks’ gestation, has increased in the last decade, however, the incidence of bronchopulmonary dysplasia (BPD) has not changed. The Ottawa Hospital introduced high frequency oscillatory ventilation (HFOV) as the primary mode of invasive ventilation for ELGA infants, based on data suggesting HFOV may be lung protective in this population.

Objective: The objective of this study is to examine the relationship between the use of primary intent HFOV and respiratory outcomes during admission. The primary outcome is total days of invasive ventilation. Secondary outcomes include moderate to severe BPD at 36 weeks corrected, and differences in respiratory severity scores (RSS) at 21 days.

Design/Methods: We performed a retrospective chart review of a cohort of ELGA infants admitted at two NICUs in Ottawa. Two epochs were compared: E1 where infants received conventional mechanical ventilation (2016 to 2019) and E2 where they received HFOV (2020 to 2024). There was a wash out period of 6 months between epochs. Data for eligible patients were collected from the electronic medical records (Epic) at both centers. The association between epoch and BPD among infants who survived to 36 weeks was modeled using multivariable logistic regression.

Results: Medical records of 224 infants were reviewed, and 52 patients were excluded due to death in the delivery room (n=21) or within the first 7 days (n=31). 172 patients were included (mean GA 24.6 weeks in E1 and 24.8 weeks in E2 and mean BW 660g in E1 and 675g in E2). In E1, 15% of infants died before discharge home, compared to 18% in E2.
For infants who survived until discharge, median (IQR) days of invasive ventilation was 27 (9,39) in E1 and 34 (15,46) in E2. The proportion with moderate to severe BPD was 32/55 (58%) in E1 vs 50/85 (59%) in E2. We failed to detect a significant association between epoch and moderate/severe BPD after adjusting for GA, use of antenatal steroids and sex (OR 0.95 (95% 0.46,1.96), p=0.9). Median (IQR) RSS at 21 days was 3.36 (2.42, 5.04) in E1 vs 3.02 (2.22, 4.41) in E2.

Conclusion(s): Data analysis is ongoing, but early results suggest no difference in total days on mechanical ventilation nor moderate to severe BPD rates after introducing HFOV as primary mode of invasive ventilation. Further analysis of lung health at hospital discharge and longitudinal RSS assessments are underway.