A comparison of high-frequency jet ventilation and synchronised intermittent mandatory ventilation in preterm lambs

Update on ventilatory management of extremely preterm infants-A Neonatal Intensive Care Unit perspective

Extremely preterm infants commonly suffer from respiratory distress syndrome. Ventilatory management of these infants starts from birth and includes decisions such as timing of respiratory support in relation to umbilical cord management, oxygenation targets, and options of positive pressure support. The approach of early intubation and surfactant administration through an endotracheal tube has been challenged in recent years by primary noninvasive respiratory support and newer methods of surfactant administration via thin catheters. Available data comparing the thin catheter method to endotracheal tube and delayed extubation in extremely preterm infants born before 28 weeks of gestation did not show differences in survival free of bronchopulmonary dysplasia. Data from numerous randomized trials comparing conventional ventilation with high-frequency oscillatory ventilation did not show differences in meaningful outcomes. Among conventional modes of ventilation, there is good evidence to favor volume-targeted ventilation over pressure-limited ventilation. The former reduces the combined risk of bronchopulmonary dysplasia or death and several important secondary outcomes without an increase in adverse events. There are no evidence-based guidelines to set positive end-expiratory pressure in ventilated preterm infants. Recent research suggests that the forced oscillation technique may help to find the lowest positive end-expiratory pressure at which lung recruitment is optimal. Benefits and risks of the various modes of noninvasive ventilation depend on the clinical setting, degree of prematurity, severity of lung disease, and competency of staff in treating associated complications. Respiratory care after discharge includes home oxygen therapy, lung function monitoring, weaning from medication started in the neonatal unit, and treatment of asthma-like symptoms.

Gestational Age Influences the Early Microarchitectural Changes in Response to Mechanical Ventilation in the Preterm Lamb Lung

Background: Preterm birth is associated with abnormal lung architecture, and a reduction in pulmonary function related to the degree of prematurity. A thorough understanding of the impact of gestational age on lung microarchitecture requires reproducible quantitative analysis of lung structure abnormalities. The objectives of this study were (1) to use quantitative histological software (ImageJ) to map morphological patterns of injury resulting from delivery of an identical ventilation strategy to the lung at varying gestational ages and (2) to identify associations between gestational age-specific morphological alterations and key functional outcomes. Method: Lung morphology was compared after 60 min of a standardized ventilation protocol (40 cm H₂O sustained inflation and then volume-targeted positive pressure ventilation with positive end-expiratory pressure 8 cm H₂O) in lambs at different gestations (119, 124, 128, 133, 140d) representing the spectrum of premature developmental lung states and the term lung. Age-matched controls were compared at 124 and 128d gestation. Automated and manual functions of Image J were used to measure key histological features. Correlation analysis compared morphological and functional outcomes in lambs aged ≤128 and >128d. Results: In initial studies, unventilated lung was indistinguishable at 124 and 128d. Ventilated lung from lambs aged 124d gestation exhibited increased numbers of detached epithelial cells and lung tissue compared with 128d lambs. Comparing results from saccular to alveolar development (120-140d), lambs aged ≤124d exhibited increased lung tissue, average alveolar area, and increased numbers of detached epithelial cells. Alveolar septal width was increased in lambs aged ≤128d. These findings were mirrored in the measures of gas exchange, lung mechanics, and molecular markers of lung injury. Correlation analysis confirmed the gestation-specific relationships between the histological assessments and functional measures in ventilated lambs at gestation ≤128 vs. >128d. Conclusion: Image J allowed rapid, quantitative assessment of alveolar morphology, and lung injury in the preterm lamb model. Gestational age-specific patterns of injury in response to delivery of an identical ventilation strategy were identified, with 128d being a transition point for associations between morphological alterations and functional outcomes. These results further support the need to develop individualized respiratory support approaches tailored to both the gestational age of the infant and their underlying injury response.

Pediatric Pulmonology year in review 2015: Part 1

Our journal covers a broad range of research and scholarly topics related to children's respiratory disorders. For updated perspectives on the rapidly expanding knowledge in our field, we will summarize the past year's publications in our major topic areas, as well as selected publications in these areas from the core clinical journal literature outside our own pages. The current review covers articles on neonatal lung disease, pulmonary physiology, and respiratory infection. Pediatr Pulmonol. 2016;51:733-739. © 2016 Wiley Periodicals, Inc.

Inflammatory indices in meconium aspiration syndrome

INTRODUCTION

Meconium aspiration syndrome (MAS) is linked to inflammation, but data on the patterns of hematological indices and C-reactive protein (CRP) in MAS are lacking. The aim of the study was to evaluate CRP, white blood cell count (WBC), absolute neutrophil count (ANC), and immature-to-total neutrophil ratio (IT-ratio) in MAS and to assess their association with disease severity.

METHODS

Retrospective cross-sectional study including 239 consecutively admitted neonates with MAS to a level III NICU. Neonates with early onset sepsis were excluded. Results Neonates with severe MAS (invasive mechanical ventilation for <7 days) and very severe MAS (invasive mechanical ventilation for ≥7 days or high frequency ventilation or ECMO) had higher CRP and IT-ratio compared to neonates with non-severe MAS (no invasive mechanical ventilation) during the first 2 days of life (CRP: 13.0 and 40.9 vs. 9.5 mg/L, P = 0.039 and <0.001, respectively) and neonates with very severe MAS had lower WBC and ANC. All four inflammatory indices correlated significantly with duration of invasive mechanical ventilation, duration of respiratory support and with length of hospital stay, arterial hypotension, and persistent pulmonary hypertension. Neonates with all four inflammatory indices beyond the normal range had a more than 20-fold increase in risk for very severe MAS.

CONCLUSION

High CRP and IT-ratio and low WBC and ANC values were closely linked to a more severe course of MAS during the early phases of the disease. These findings reflect the role of inflammation in the pathogenesis of MAS. Pediatr Pulmonol. 2016;51:601-606. 2015 Wiley Periodicals, Inc.