Abstract: A method and system for detecting nerve status and relative movement between a nerve and a proximity electrode. The method determines relative movement between a nerve and a proximity electrode by applying multiple signals to a calibration electrode where the energy level of each signal induces a predetermined nerve response. The method also applies multiple signals to the proximity electrode where the energy level of each signal also induces a predetermined nerve response. Based on the variation of the energy level of signals required to induce predetermined nerve responses, the method may detect relative movement between a nerve and a proximity electrode and nerve status.

Abstract: A cannula is provided with one or more pressure transducers for measuring fluid pressure interiorly or exteriorly of the cannula. The pressure transducers may be mounted integrally with the tubular wall defining the main lumen of the cannula, or they may comprise differential pressure transducers mounted in dedicated lumens in communication with the main lumen. The pressure measurements from the transducers is used to determine fluid flow rate.