Ultrasound-guided arterial cannulation or by pulse palpation in the intensive care unit Ignacio Oulego-Erroz; Juan Mayordomo-Colunga; Rafael González-Cortés; María Sánchez-Porras; Ana Llorente-de la Fuente; Sira Fernández-de Miguel; Mónica Balaguer-Gargallo; Manuel Frías-Pérez; Antonio Rodríguez-Nuñez;