The NaPier tube is a self-expanding port-access tube for insertion into body passages. A NaPier tube is typically used with an endoscope disposed within the lumen of an unactivated tube to enable visual navigation to place the tube in a passage. A NaPier tube comprises a shape-memory element, wall material, and a removable sheath. A tear-away, removable sheath maintains the shape-memory element in a compressed state. Upon placement of the distal end of a NaPier tube in the target location in a passage, the sheath is ruptured and removed through the port and the shape-memory element expands to its memorized geometries. Embodiments of the NaPier tube are adapted by length and memorized dimensions for endotracheal intubation and for port-access procedures, such as endoscopic surgery.