324 - Tidal volume levels after preterm birth: Gently does it

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 324
Publication Number: 324.348

Prue Pereira-Fantini, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Monique E. Fatmous, The Royal Children's Hospital, Melbourne, Victoria, Australia; Kelly Kenna, Murdoch Children's Research Institute, Melbourne, Victoria, Australia; Ellen Douglas, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Elizabeth J. Perkins, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia; Arun Sett, Murdoch Children's Research Institute, Melbourne, Victoria, Australia; David Tingay, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Sophia I. Dahm, Murdoch Children's Research Institute, Parkville, Victoria, Australia

Presenting Author(s)

PP

Prue Pereira-Fantini, B. Sci (Hons), PhD (she/her/hers)

Senior Research Officer
Murdoch Children's Research Institute
Parkville, Victoria, Australia

Background: Tidal ventilation is essential in supporting the transition to air-breathing at birth, but excessive tidal volume (V_T) is an important factor in preterm lung injury. There is limited information regarding the most lung protective tidal volume (VT) strategy to apply at birth, Most preterm lamb studies have used V_T at 7 ml/kg however we have previously identified that a dynamic positive end-expiratory pressure (PEEP) strategy at birth, in which lambs are transiently exposed to a reduced VT of 3-5 ml/kg at 60-120s post-birth, reduces lung injury in preterm lambs compared to a static PEEP strategy. This raises the question as to whether the injury benefits were related to lower VT exposure, after a brief period of higher VT to aid aeration, rather than the higher PEEP.

Objective:

The objective of this study was to determine the role of different levels of V_T during positive pressure ventilation (PPV) on initiating early lung injury pathways in the preterm lung.

Design/Methods: 124-127d preterm lambs were randomly allocated to 15-min of volume-targeted PPV with different V_T levels in the first 3 min after birth (Table 1). Lung mechanics and volumes (using electrical impedance tomography) were measured throughout, and lung injury assessment performed on post-mortem samples (using histology, BALF total protein concentration, and mass spectrometry-based proteomics).

Results: Lung injury and proteome results presented in Table 1. V_T, inflating pressure, lung compliance and end-expiratory volume (aeration) were similar in all groups from 4 min, as was histology and BALF concentration. The transient decrease in V_T in the V_Talt group caused increased ventilation heterogeneity. From the 1610 proteins identified in the lung, 3-fold more proteins were altered with V_Talt compared with V_Tstaticor V_Tinc strategies (Figure 1). Gene set enrichment analysis identified different biological processes, cellular components and pathways enriched in each strategy including increased immune activation associated with V_Talt.

Conclusion(s): Our finding of comparable lung physiology and volutrauma across V_T groups challenges the paradigm that there is a need to rapidly aerate the preterm lung at birth. Increased lung injury and ventilation heterogeneity was identified when initial high V_T was suddenly decreased during respiratory support at birth, further supporting the benefit of a gentle V_T approach.