Percutaneous versus surgical strategy for tracheostomy: protocol for a systematic review and meta-analysis of perioperative and postoperative complications - Klotz, Rosa; Klaiber, Ulla; Grummich, Kathrin; Probst, Pascal; Diener, Markus K.; Büchler, Markus W.; Knebel, Phillip (BioMed Central, 2016)