An adjustable length tracheostomy tube, Bivona™, which assumes a curve on insertion, has a tendency to straighten itself in situ. The straightening force, measured electronically, was maximal (0.21 Newton) when a tube was bent 90 degrees. We observed particular clinical disadvantages of these tubes—that of tracheal ulceration (1 case), distortion of soft tracheal graft tissue (1 case) and airway obstruction when the tip embedded into the tracheal wall (1 case).
