290 - Tidal volumes of ventilated extreme premature infants in the first 4 weeks of life and development of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a major complication of extreme premature infants (EPI). Volume-targeted ventilation (VTV) is useful in preventing BPD, with volume-guarantee ventilation (VGV) being a preferred mode. Available data to guide the tidal volumes (TV) prescribed for EPIs after the 1^st week of life is limited. However, larger TV could cause volutrauma and increase the risk of BPD.

Objective:

To determine the association between recorded TV (cc/kg) of EPIs on days of life (DOL) 7, 14, 21 and 28 and death and/or BPD at 36 weeks PMA as defined by the Vermont Oxford Network.

Design/Methods:

Single-centered, retrospective cohort review of medical records of premature infants less than 28 weeks admitted to a Level 4 NICU from January 2012 to December 2021. Data abstracted included: demographics, maternal and birth data, and ventilator data of VGV mode and respiratory severity score (RSS) at DOL 7, DOL 14, DOL 28 until death or discharge. Mixed-effects linear regression models were fit to make unadjusted comparisons of TV for patients experiencing versus not experiencing BPD and a BPD-death composite event, as well as to make these comparisons after controlling for RSS at each time point.  A first-order autoregressive covariance structure was used for the mixed-effects linear regression models in order to accommodate the correlation between repeated TV measurements over time for the same patient.

Results:

A total of 583 tidal volume measurements over the first 28 DOL from 327 patients were analyzed. 199 (34.1%) tidal volume measurements were obtained for DOL 7, 159 (27.3%) for DOL 14, 119 (20.4%) for DOL 21 and 106 (18.2%) for DOL 28. Of the 327 patients, 227 (69.4%) experienced BPD and 261 (79.8%) experienced BPD-death. Table 1 summarizes the characteristics of the 327 patients.

Vtmech was marginally higher (0.2799 ± 0.1553 cc/kg higher, p = 0.073) for those experiencing the BPD-death composite event after controlling for the corresponding DOL. TV measurements over the first 28 DOL for those experiencing versus not experiencing BPD or the BPD-death composite event did not differ significantly after controlling for the corresponding DOL. ± RSS (Table 2).

Conclusion(s):

In the above study, there was no association between recorded TV (cc/kg) of EPIs during the first 28 DOL and BPD or BPD-death. As ventilator-induced lung injury increases the risk of BPD/death in EPIs, further prospective studies are warrant, as well as addressing other ventilator variables.