1. Anesthesiology and Perioperative Medicine, Complejo Hospitalario Universitario de A Coruña, A Coruña, Spain
2. Spanish Difficult Airway Group (GEVAD), Spain
3. Anaesthesiology and Perioperative Medicine, Salamanca University Hospital, Salamanca, Spain
4. Anaesthesiology and Perioperative Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain