2 Department of Otolaryngology-Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI.
3 UK National Tracheostomy Safety Project, NHS England, London, United Kingdom.
4 Department of Anaesthesia & Intensive Care Medicine, Manchester University NHS Foundation Trust, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom.
5 Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.
6 Department of Anesthesiology and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy.