Design and validation of an epidural needle insertion simulator with haptic feedback for training resident anaesthesiologists

Epidural needle insertion is a complex procedure that requires training of residents´ psychomotor skills using simulators, alternative to training on cadavers and real patients. Haptic feedback is a key feature in the development of such simulators. Its three important aspects are: i) to provide a realistic simulation, ii) to objectively measure the performance of users, and iii) to classify the users. A high-fidelity simulator is often considered to be the best choice to produce a realistic simulation. However, the trade-off between fidelity of the simulator to its cost is still a key issue and it depends on the objective of simulation. One way to address this issue is to simulate only the important (clinically) haptic cues. In this paper a low-fidelity custom built two degree-of-freedom (1DOF for needle insertion and 1DOF for needle orientation along the midline) haptic interface has been developed and clinically validated by expert/resident anaesthesiologists. The proposed haptic interface provides high translational force by means of a motor and rotational torque by means of a brake. The simulator simulates needle-tissue and needle-bone interaction forces. It has a graphical user interface that displays a cross-sectional image (midline) of the patient´s lumbar anatomy. It also incorporates simulation of different virtual patients. The initial face and construct validity tests show promising results for further investigation.