A medical tube has one or more permanent passive integrated transponders associated therewith that are capable of being located by a detection apparatus which senses the electromagnetic field strength gradient generated by each passive integrated transponder associated with the medical tube and indicates the value of the gradient to the user. In one embodiment, the passive integrated transponder is associated with the distal end of an endotracheal medical tube in a fixed orientation with an electromagnetic field pointing at a preferred angle of no more than 15 degrees to the longitudinal axis of the medical tube. The passive integrated transponders static electromagnetic field is sensed by the detection apparatus and indicates the location of the distal end of the medical tube within a body.
