Abstract: A device to detect the location of a magnet coupled to an indwelling medical device within a patient uses three or more sets of magnetic sensors each having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by the magnet and provides data indicative of the direction of the magnet in a three-dimensional space. The device uses fundamental equations for electricity and magnetism that relate measured magnetic field strength and magnetic field gradient to the location and strength of a magnetic dipole. The device uses an iterative process to determine the actual location and orientation of the magnet. An initial estimate of the location and orientation of the magnet results in the generation of predicted magnetic field values. The predicted magnetic field values are compared with the actual measured values provided by the magnetic sensors.

Abstract: There is disclosed a tracheal tube for insertion into the trachea of a patient. The tracheal tube includes a tube portion having a distal end, and a signal source associated with the tube portion at a predefined distance from its distal end. The tracheal tube is inserted into the trachea such that the signal source is immediately posterior to the patient's cricothyroid ligament. Methods related to confirming proper placement of the tracheal tube by detecting the signal source immediately posterior to the patient's cricothyroid ligament are also disclosed.