BACKGROUND: The preterm infant is particularly vulnerable to hypotension and inadequate cerebral perfusion, due to immaturity of the cardiovascular system. Preterm birth is also associated with an inflammatory response, with consequences both in the peripheral vasculature and the brain. The complex interactions between adequate blood supply and inflammation, may significantly contribute to brain injury and poor neurological outcomes.
AIM: To determine whether early blood transfusion is more effective than saline to support cardiovascular function, leading to improved cerebral oxygenation and brain outcomes at 12h postnatal age (PNA).
METHODS: Preterm piglets (98/115 d gestation) were sedated, ventilated and catheterised, with continuous monitoring of blood pressure, heart rate and cerebral oxygenation (near-infrared spectroscopy) from baseline until end of experiment. Animals were randomised to receive either no volume expansion (untreated), blood or saline (low dose, 10ml/kg or high dose, 20ml/kg) for 1h commencing at 5h PNA. Animals were euthanised at 12h PNA, brains were sectioned and fixed- for histopathology (H&E) and immunofluorescent labelling (GFAP and IBA-1).
RESULTS: Arterial blood pressure and cerebral oxygenation were higher in piglets receiving blood than in those animals receiving saline or no treatment. Saline treated animals had greater brain pathology in the parietal cortex and CA1 region of the hippocampus compared with blood transfusion groups, as evidenced by cellular atrophy and dark, condensed nuclei (H&E staining). Saline treated animals exhibited increased activated microglial labelling (IBA-1) in the white matter tracts of the parietal cortex compared with blood treated and 0h littermates.
CONCLUSION: More effective cardiovascular support was associated with reduced brain injury and fewer activated microglia, indicating that support of blood pressure may have a role in protecting the vulnerable preterm brain.