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Lower Distending Pressure Improves Respiratory Mechanics in Congenital Diaphragmatic Hernia Complicated by Persistent
David Guevorkian1, Sebastien Mur2, Eric Cavatorta3
1Neonatal Intensive Care, Department of Neonatology, Marie Curie Public Hospital, Charleroi, Belgium; Department of Neonatology, Jeanne de Flandre Hospital, University Hospital of Lille, F-59000 France.
Insights
Lower distending pressures improve respiratory mechanics and pulmonary circulation in newborns with congenital diaphragmatic hernia (CDH) and persistent pulmonary hypertension (PPHN). This suggests CDH lungs may be prone to overdistension.
Area of Science:
- Neonatal Medicine
- Pediatric Pulmonology
- Critical Care
Background:
- Congenital diaphragmatic hernia (CDH) often leads to persistent pulmonary hypertension (PPHN) in newborns.
- Understanding optimal ventilatory strategies is crucial for managing these complex conditions.
Purpose of the Study:
- To evaluate the impact of different positive end-expiratory pressure (PEEP) levels on respiratory mechanics and pulmonary circulation in infants with CDH and PPHN.
Main Methods:
- A prospective, randomized, crossover pilot study involving 17 infants with CDH and PPHN.
- Infants received 2 cmH2O and 5 cmH2O of PEEP in a crossover design.
- Respiratory mechanics, lung function, and hemodynamic variables were assessed using Doppler echocardiography.
Main Results:
- Lower PEEP (2 cmH2O) resulted in greater tidal volume, minute ventilation, and respiratory system compliance compared to higher PEEP (5 cmH2O).
- Lower PEEP reduced PaCO2 and ventilation index, and improved postductal oxygen saturation.
- Hemodynamic parameters, including left ventricle diameter and pulmonary blood flow, were more favorable at lower PEEP levels.
Conclusions:
- Lower distending pressures are associated with improved respiratory mechanics in infants with mild-to-moderate CDH post-repair.
- Hypoplastic lungs in CDH may be susceptible to overdistension, indicating a need for careful pressure management.
Objective:
To investigate the effects of distending pressures on respiratory mechanics and pulmonary circulation in newborn infants with congenital diaphragmatic hernia (CDH) and persistent pulmonary hypertension (PPHN).
Study Design:
In total, 17 consecutive infants of ≥37 weeks of gestational age with CDH and PPHN were included in this prospective, randomized, crossover pilot study. Infants were assigned randomly to receive 2 or 5 cmH2O of positive end-expiratory pressure (PEEP) for 1 hour in a crossover design. The difference between peak inspiratory pressure and PEEP was kept constant. Respiratory mechanics, lung function, and hemodynamic variables assessed by Doppler echocardiography were measured after each study period.
Results:
At 2 cmH2O of PEEP, tidal volume and minute ventilation were greater (P < .05), and respiratory system compliance was 30% greater (P < .05) than at 5 cmH2O. PaCO2 and ventilation index were lower at 2 cmH2O than at 5 cmH2O (P < .05). Although preductal peripheral oxygen saturation was similar at both PEEP levels, postductal peripheral oxygen saturation was lower (median [range]: 81% [65-95] vs 91% [71-100]) and fraction of inspired oxygen was greater (35% [21-70] vs 25% [21-60]) at 5 cmH2O. End-diastolic left ventricle diameter, left atrium/aortic root ratio, and pulmonary blood flow velocities in the left pulmonary artery were lower at 5 cmH2O.
Conclusions:
After surgical repair, lower distending pressures result in better respiratory mechanics in infants with mild-to-moderate CDH. We speculate that hypoplastic lungs in CDH are prone to overdistension, with poor tolerance to elevation of distending pressure.
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