Telepresence interface with applications to microsurgery and surgical simulation.

To address the needs for performing microsurgical procedures, the SRI telepresence surgery workstation has been combined with a pair of micromanipulator arms. The prototype microsurgery system has been tested with ex-vivo tasks similar to those required for surgical procedures, such as cutting, grasping, suturing, and knot tying. Initial animal testing has been done on a rat model in which end-to-end anastomosis of the femoral artery (approximately 1 millimeter in diameter) was completed with ten rats, and 100% patency was obtained. To address the needs of surgical training, SRI has begun to develop a system that uses a 6-DOF telepresence workstation. A computer-generated stereo image is reflected in a mirror and appears to be superimposed on the surgeon's hands, creating an immersive and realistic environment. Tools held in the surgeon's hands are connected to left- and right-hand manipulators that both continuously measure tool position/orientation and apply force/torque to the tools. Furthermore, the visual image and tool locations are registered, so that the user perceives that he or she is looking at and moving the simulated tools in the visual image.

Noninvasive intracranial pressure monitoring.

Because skull elasticity has been demonstrated (through holographic interferometry), the assumption was made that even a small change in intracranial hydrostatic pressure might change the bitemporal diameter of the skull measurably. The authors devised a relatively noninvasive instrument for measuring skull diameter changes with changing intracranial pressure and evaluated its performance in cadavers and dogs, with encouraging results. With this method of measuring intracranial pressure, changes in pressure of as little as 2 mm Hg can be detected. The method measures relative rather than absolute pressure; it is postulated that this shortcoming can be overcome through further effort.