Positive end-expiratory pressure increases intracranial pressure but not pressure reactivity index in supine and prone positions: a porcine model study - Hammervold, Rønnaug; Beqiri, Erta; Smielewski, Peter; Storm, Benjamin S.; Nielsen, Erik W.; Guérin, Claude; Frisvold, Shirin K. (Frontiers in Medicine, 2025)