Surfactant phospholipids in the bronchoalveolar lavage fluid (BALF) of children who develop acute lung injury (ALI)

Introduction

Children with ALI represent 5% of admissions to our Paediatric Intensive Care Unit [1]. Although there has been much research in adults with ALI, little is known about the pathophysiology in children [2]. More specifically there is a paucity of information on the pulmonary phospholipid (PL) changes during ALI children.

Methods

All children without pre-existing lung pathology who developed ALI (defined as PaO₂/FiO₂ < 300 mmHg [39.5 kPa] and bilateral infiltrates seen on frontal chest X-ray [2]) were eligible for the study within 18 hours of the diagnosis. Following parental consent, BALF was collected on days 1–4, then weekly and immediately prior to extubation. BALF was filtered to remove debris, centrifuged at 400 × g and 4°C for 10 min to remove cells and the supernatant stored at -80°C prior to analysis. Molecular species compositions of phosphatidylcholine (PC), were determined by electrospray ionisation mass spectrometry of lipid extracts of BALF supernatants. Children without any pulmonary pathology who were intubated following surgical procedures acted as controls. The study was approved by the local research ethics committee.

Results

Over 9 months, 40(8.8%) children of 452 admissions developed ALI. Ten of 26 eligible children were enrolled in the study; six parents declined consent and 10 children were either too unstable for BALF collection or were not recruited in time. In the study group, the dipalmitoyl PC (DPPC) content in BALF decreased from control values (42.8 ± 6.5% of total PC) to a minimum of 23.1 ± 11.9% (P < 0.01) between days 2–3, but increased to 37.8 ± 4.8% pre-extubation. These changes were accompanied by reciprocal increases in the concentrations of monounsaturated PC species characteristic of inflammatory cells.

Conclusion

Changes in the PC profile of BALF samples in children with ALI indicate that there is an increase in the cellular breakdown products. We speculate that this alteration in the PC profile with a lowering of DPPC may contribute to the disease process of ALI in children.