[Clinical experiences with an automatic collision warning system: instrument navigation in endoscopic transnasal surgery].

PROBLEM: The goal of this work is the extension of instrument navigation with a collision warning function. With the help of an additional distance display and warning system the performance of surgical navigation systems should be improved. MATERIAL AND METHODS: The collision warning system (DCS) is an extension of an optoelectric navigation system (NPU, Karl Storz GmbHC Phacon, Leipzig). Altogether 450 measurement pairs for the analysis of surgical accuracy to the risk structure (frontal skull base, lamina papyracea, internal carotid artery) were available. To examine the influence on the clinical process, a prospective analysis of intraoperative complications was carried out. Of the 104 FESS patients, two groups, one of 56 patients with only navigation (NAV) and one of 48 patients (NAV+DCS), were examined. Efficiency was evaluated on the basis of times for system preparation and intraoperative application. RESULTS: A significant increase in the assumed and actual distance values between instrument tip and risk structure using the collision warning system was seen at 76%. The complication rate was more favorable for the NAV+DCS group. The time needed for preparation of the navigation system with the application of the collision warning system increased on average by 48%, or 1.2 min. However, the relation between preparation time and utilization time was approximately the same at 53.5% in the NAV group and 57.4% in the NAV+DCS group. CONCLUSIONS: This work supports the clinical use and efficiency of a collision warning system as an addition to well-known instrument navigation in endo- and transnasal surgery. The segmenting algorithm is suitable for clinical requirements.