Brain inflammation induced by severe asphyxia in newborn pigs and the impact of alternative resuscitation strategies on the newborn central nervous system.

BACKGROUND

We compared the current guidelines for neonatal resuscitation with alternative measures and aimed to find out whether this modulated brain inflammation.

METHODS

Progressive asphyxia was induced in 94 newborn pigs until asystole. With the reference being resuscitation guidelines, 30 s of initial positive-pressure ventilation before compression (C) and ventilation (V) (C:V; 3:1) in 21% oxygen, pigs were randomized to (i) ventilation for 30, 60, or 90 s before chest compressions; (ii) C:V ratios of 3:1, 9:3, or 15:2; or (iii) 21% or 100% oxygen. Concentrations of inflammatory markers in the cerebrospinal fluid (CSF) and gene expression in the hippocampus and frontal cortex were measured for different interventions.

RESULTS

In CSF, S100 was higher with 90 s than with 30 or 60 s of initial positive-pressure ventilation, whereas concentrations of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were higher with 30 than with 60 s. Matrix metalloproteinase-2 (MMP-2) and intracellular adhesion molecule 1 (ICAM-1) were higher with 30 than with 60 s. No other comparison between ratios and oxygen concentrations used yielded significant results.

CONCLUSION

With respect to signs of brain inflammation, newly born pigs at asystole should be ventilated for longer than 30 s before chest compressions start. C:V ratios of 9:3 and 15:2 as compared with 3:1, or air instead of pure oxygen, did not modulate inflammatory markers.