Effect of overhang and stiffness on accessibility of catheter tip to lung defects under surgical constraints

BACKGROUND: Steering a catheter tip to a defective spot on a lung during fibrin glue application under pleurography (FGAP) constitutes a very challenging task. Accurate control of tip position/slope of steerable catheters is critical for providing glue to air-leaking defects on lung during FGAP. Steerable catheters are composed of multiple segments with different flexural rigidities and experience nonlinear deformation. Therefore, predicting tip position with accuracy is difficult. The purpose of this paper is to present a novel method that can accurately control the tip of the catheter, and thus enhance its target accessibility. METHODS: The tip position of a deflected steerable catheter can be accurately predicted using a simulation tool depicting the curvature of a bent catheter based on a mechanics of materials analysis. The proposed method utilizes the simulation tool to enhance the target accessibility of the catheter’s tip. This assists medical doctors to not only select the optimal catheter prior to operation, but also to steer the catheter to the defects effectively. Simulation reliability is tested by performing a catheter deflection experiment and measuring the tip position. RESULTS: The simulation result accurately predicts the location of the catheter tip with an error of less than 5 mm to the experimental results. CONCLUSIONS: Controlling pull-wire tensions and overhang lengths based on simulation results substantially improves the target accessibility of the catheter tip.