The nociceptive withdrawal reflex during spinal analgesia in pigs undergoing veno-arterial extracorporeal membrane oxygenation: a prospective observational study - Petrucci, Mariafrancesca; Spadavecchia, Claudia; Bachmann, Kaspar F.; Berger, David; Mirra, Alessandro; Casoni, Daniela (Frontiers in Veterinary Science, 2024)