New indicators for optimal lung recruitment during high frequency oscillator ventilation

Previous research has demonstrated the potential benefit derived from the combination of high frequency oscillatory ventilation and volume guarantee mode (HFOV-VG), a procedure that allows us to explore and control very low tidal volumes. We hypothesized that secondary spontaneous change in oscillation pressure amplitude (∆Phf), while increasing the mean airway pressure (MAP) using HFOV-VG can target the lung recruitment.

METHODS

A two-step animal distress model study was designed; in the first-step (ex vivo model), the animal's lungs were isolated to visually check lung recruitment and, in the second one (in vivo model), they were checked through arterial oxygen partial pressure improvement. Baseline measurements were performed, ventilation was set for 10 min and followed by bronchoalveolar lavage with isotonic saline to induce depletion of surfactant and thereby achieve a low compliance lung model. The high-frequency tidal volume and frequency remained constant and the MAP was increased by 2 cmH₂ O (ex vivo) and 3 cmH₂ O steps (in vivo) every 2 min. Changes in ΔPhf to achieve the fixed volume were recorded at the end of each interval to describe the maximum drop point as the recruitment point.

RESULTS

Fourteen Wistar Han rats were included, seven on each sub-study described. After gradual MAP increments, a progressive decrease in ΔPhf related to recruited lung regions was visually demonstrated. In the in vivo model we detected a significant comparative decrease of ΔPhf, when measured against the previous value, after reaching a MAP of 11 cmH₂ O up to 17 cmH₂ O, correlating with a significant improvement in oxygenation.

CONCLUSION

The changes in ∆Phf, linked to a progressive increase in MAP during HFOV-VG, might identify optimal lung recruitment and could potentially be used as an additional lung recruitment marker.

Beractant and poractant alfa in premature neonates with respiratory distress syndrome: a systematic review of real-world evidence studies and randomized controlled trials

Findings from previous meta-analyses of randomized clinical trials (RCTs) in premature infants with respiratory distress syndrome (RDS) varied as to whether clinical outcomes differed by type of animal-derived pulmonary surfactant; real-world evidence (RWE) was excluded. We extracted study characteristics and outcomes from full-text articles from a systematic search for studies that compared beractant with poractant alfa for RDS in preterm infants. RWE data were tabulated; RCT data were subjected to meta-analyses. Designs, patient characteristics, and follow-up durations varied widely among studies (4 RWE, 15 RCT). RWE studies with adjusted odds ratios (ORs) found no statistically significant between-treatment differences in outcomes. In RCT meta-analyses, no statistically significant between-treatment differences were observed for death (OR [95% confidence interval], 1.35 [0.98-1.86]), bronchopulmonary dysplasia (1.25 [0.96-1.62]), pneumothorax (1.21 [0.72-2.05]), and air leak syndrome (2.28 [0.82-6.39]). Collectively, outcomes were similar with beractant and poractant alfa in RWE studies and pooled RCTs.

Initial respiratory management in preterm infants and bronchopulmonary dysplasia

BACKGROUND

Ventilator injury has been implicated in the pathogenesis of bronchopulmonary dysplasia. Avoiding invasive ventilation could reduce lung injury, and early respiratory management may affect pulmonary outcomes.

OBJECTIVE

To analyze the effect of initial respiratory support on survival without bronchopulmonary dysplasia at a gestational age of 36 weeks.

DESIGN/METHODS

A prospective 3-year observational study. Preterm infants of <32 weeks gestational age were classified into 4 groups according to the support needed during the first 2 hours of life: room air, nasal continuous positive airway pressure, intubation/surfactant/extubation and prolonged mechanical ventilation (defined as needing mechanical ventilation for more than 2 hours).

RESULTS

Of the 329 eligible patients, a total of 49% did not need intubation, and 68.4% did not require prolonged mechanical ventilation. At a gestational age of 26 weeks, there was a significant correlation between survival without bronchopulmonary dysplasia and initial respiratory support. Preterm infants requiring mechanical ventilation showed a higher risk of death and bronchopulmonary dysplasia. After controlling for gestational age, antenatal corticosteroid use, maternal preeclampsia and chorioamnionitis, the survival rate without bronchopulmonary dysplasia remained significantly lower in the mechanically ventilated group.

CONCLUSIONS

In our population, the need for more than 2 hours of mechanical ventilation predicted the development of bronchopulmonary dysplasia in preterm infants with a gestational age >26 weeks (sensitivity =89.5% and specificity = 67%). The need for prolonged mechanical ventilation could be an early marker for the development of bronchopulmonary dysplasia. This finding could help identify a target population with a high risk of chronic lung disease. Future research is needed to determine other strategies to prevent bronchopulmonary dysplasia in this high-risk group of patients.