Increasing the safety and precision of medical tissue puncture

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis. Vita (page 126)Includes bibliographical references (pages 128-132).Tissue puncture is ubiquitous in medicine, from percutaneous injections and biopsies to laparoscopic surgical access, epidural anesthesia, and cranial drilling; over 10 million puncture procedures are performed each year in the US alone. At the moment of puncture when the tissue fails at the tip of a puncture device, the tip of the device may travel farther than intended and impact underlying tissues or organs, causing dangerous and potentially deadly complications. Tissue puncture is performed on significantly varied tissue types and patient populations with countless different methods and devices; however, it is crucial to note that essentially all puncture procedures follow a common set of fundamental physical principles and are governed by many of the same characteristic parameters and phenomena. As such, broadly applicable devices and strategies may be developed to increase the safety and precision of tissue puncture across all medical disciplines. In this work we develop a general definition and common theoretical basis for medical tissue puncture, and extract key parameters which can be optimized to increase the safety and precision of puncture procedures. This work has resulted in the development of a test apparatus to measure tissue surface deflection during high-velocity deep tissue puncture. In addition, we have experimentally demonstrated that during deep tissue puncture with medical needles, for certain needle-tissue systems there exists an optimal insertion velocity such that tissue deflection is minimized. A first-order theoretical model is developed and suggests that this optimum velocity behavior is due to increasing hydrodynamic friction forces at higher insertion velocities. From this common fundamental approach to tissue puncture, several devices have been developed which may be applied to a variety of medical procedures to increase puncture precision. Specifically, a flexural tip-retraction mechanism actively opposes the forward "plunge" acceleration of a puncture device and is scalable for many medical and non-medical puncture applications. In addition, audible-frequency vibration of a puncture device is found to significantly decrease insertion force without causing additional immediate tissue damage, as confirmed by live tissue histology study. Results of this work may have significant effects on future device development.by Nikolai David Michael Begg.Ph. D