Intravenous versus epidural analgesia to reduce the incidence of gastrointestinal complications after elective pancreatoduodenectomy (the PAKMAN trial, DRKS 00007784): study protocol for a randomized controlled trial - Klotz, Rosa; Hofer, Stefan; Dörr-Harim, Colette; Tenckhoff, Solveig; Bruckner, Thomas; Klose, Christina; Diener, Markus K.; Weigand, Markus A.; Büchler, Markus W.; Knebel, Phillip (BioMed Central, 2016)