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There is increasing realization that some tasks can be performed significantly better by humans than robots but, due to associated hazards, distance, etc., only a robot can be employed. Telemedicine is one area where remotely controlled robots can have a major impact by providing urgent care at remote sites. In recent years, remotely controlled robotics has been greatly advanced and the NASA Johnson Space Center’s robotic astronaut, “Robonaut,” is one such exa mple. Unfortunately, due to the unavailability of force and tactile feedback the operator must determine the required action by visually examining the remote site and therefore limiting the tasks that Robonaut can perform. There is a great need for dexterous, fast, accurate teleoperated robots with the operator's ability to "feel" the environment at the robot's field. The authors conceived a haptic mechanism called MEMICA (Remote MEchanical MIrroring using Controlled stiffness and Actuators) that can enable the design of high dexterity, rapid response, and large workspace haptic system. The development of a novel MEMICA gloves and virtual reality models are being explored to allow simulation of telesurgery and other applications. The MEMICA gloves are being designed to provide intuitive mirroring of the conditions at a virtual site where a robot simulates the presence of a human operator. The key components of MEMICA are miniature electrically controlled stiffness (ECS) elements and Electrically Controlled Force and Stiffness (ECFS) actuators that are based on the use of Electro-Rheological Fluids (ERF). In this paper the design of the MEMICA system and initial experimental results are presented.

An in vivo study of vascular welding with a fiber-delivered argon laser was conducted using a canine model. Longitudinal arteriotomies and venotomies were treated on femoral vein and artery. Laser energy was delivered to the vessel wall via a 400 micrometer optical fiber. The surface temperature at the center of the laser spot was monitored in real time using a hollow glass optical fiber-based two-color infrared thermometer. The surface temperature was limited by either a room-temperature saline drip or direct feedback control of the laser using a mechanical shutter to alternately pass and block the laser. Acute patency was evaluated either visually (leak/no leak) or by in vivo burst pressure measurements. Biochemical assays were performed to investigate the possible laser-induced formation or destruction of enzymatically mediated covalent crosslinks between collagen molecules. Viable welds were created both with and without the use of feedback control. Tissues maintained at 50 degrees Celsius using feedback control had an elevated crosslink count compared to controls, while those irradiated without feedback control experienced a decrease. Differences between the volumetric heating associated with open and closed loop protocols may account for the different effects on collagen crosslinks. Covalent mechanisms may play a role in argon laser vascular fusion.

This study evaluated the acute and chronic effects of diode laser (960 nm) prostatectomy using a Prolase II fiber in a canine model (n equals 5). The laser fiber consists of a 1000 um quartz fiber which reflects a cone of laser energy, at 45 degree(s) to the axis of the fiber, into the prostatic urethra (Visual Laser Ablation of Prostate). Perineal access was used to guide a 15.5 Fr cystoscope to the level of the prostate. Under visual guidance and continual saline irrigation, 60 watts of laser power was delivered for 60 seconds at 3, 9, and 12 o'clock and 30 seconds at the 6 o'clock (posterior) positions for a total energy fluence of 12,600 J. One prostate received an additional 60 second exposure at 3 and 9 o'clock for a total fluence of 19,800 J. The prostates were evaluated at one day (n equals 1) and 8 weeks (n equals 4). The histopathology of laser effects at one day show areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 17.5 mm (cross sectional diameter). The histopathology of the 8 week laser treated animals demonstrated dilated prostatic urethras with maximum cross- sectional diameter of 23.4 mm (mean equals 18.5 +/- 3.9 mm). This study demonstrates the effectiveness of diode laser energy for prostatic tissue coagulation and eventual sloughing. The results also demonstrate the safety of diode laser energy, with similar tissue response as seen with Nd:YAG laser, for laser prostatectomy.

Intraluminal vascular ultrasound (IVUS) is developing rapidly as a method to define the transmural anatomy of vascular structures for both diagnostic and therapeutic applications. Current devices use various configurations of transducers at the end of an intraluminal catheter to make real time images of cardiac structures and vessel walls. These devices may have diagnostic applications, particularly at the time of angiography or catherization for symptomatic cardiovascular disease.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Tissue fusion by laser energy is an intriguing and very promising new applications for laser technology. In comparison to using high laser energy to ablate tissue as in the angioplasty application, laser tissue fusion is possible in any soft tissue by delivering appropriate low levels of energy to the opposed tissue surfaces. This technology is particularly appealing for vascular applications in making sutureless blood vessel anastomosisand for securing the endpoints of endarterectomies and dissection planes. Although there have been limited evaluations of this technology, the preliminary experimental and clinical data is very promising for continued development and application. Vascular tissue fusion or welding by lasers is performed by directing a low energy beam at the opposed edges of the repair. The energy is applied by moving the beam back and forth along the fusion line or, in certain cases, by delivering the energy in "spot" applications. Vessel sealing is apparent in the majority of fusions to the trained eye, as is nonunion caused by inadequate energy delivery, or tissue coagulation or vaporization from excessive energy exposure. Laser repairs can be fashioned in time intervals comparable to or slightly longer than those required for suture repairs. Precision of tissue apposition at the time of fusion is a critical parameter which affects the rate of healing and tensile strength of tissue welds. A gap between the vessel edges or blood at the interface compromises weld strength.

This study evaluates the ability of intravascular ultrasound (IUS) to image normal and mildly diseased human ileo-femoral vessels during angioplasty or vascular bypass procedures. Five Fr. and 8Fr. rotating A scan IUS catheters were used to obtain 43 images in 4 superficial femoral arteries, and 5 iliac arteries in 8 vascular surgery patients. Luminal cross sectional (LCS) areas measured by IUS were compared to LCS areas calculated by uniplanar angiography (ANGIO) at the same location in the vessel. The correlation between the areas (IUS vs ANGIO) for all images was significant (n = 43, r = 0.90, P

Tissue fusion by laser energy is an intriguing arxi very promising new application for laser technology. In coniparison to using high laser energy to ablate tissue as in the aricplasty application, laser tissue fusion is possible in any soft tissue by deliverir appropriate lc levels of energy to the cppose tissue surfaces. This technology is particularly appealing for vascular applications in inakir sutureless blood vessel anastornosis and for securir the endpOints of erxarterect:amies ani dissection planes. Although there have been limitel evaluations of this technology the preliminary experimental ar1 clinical data is very promisir for continu development arid application.

Vascular tissue fusion by lasers is performed by directing a low energy beam at the apposed edges of the repair. The tissues are approximated with stay sutures or non-reflective instruments and laser energy is passed back-and-forth over the anastomotic site until fusion is achieved. Vessel welding is apparent to the trained eye, as is nonunion caused by inadequate energy delivery. Conversely, excessive energy delivery results in obvious tissue coagulation or vaporization. Fiberoptic laser transmission and hand-eye coordination are adequate for repair or anastomosis of vessels with diameters greater than 3 mm, whereas magnification and precise mechanical control of the laser beam are necessary for microanastomoses of smaller vessels. The laser power (watts, W), and the amount of energy and time required (energy fluence or power density) vary according to the type of laser and the size of the vessels. Although laser repairs can be fashioned in time intervals equal to or slightly longer than those required for suture repairs, the optimum wavelengths and laser parameters for different types of seals are not yet established.

The thermal properties and maximum temperatures attained during CO 2 (n=20) and Argon (n=20) laser welded repair of arteries were compared in a canine model. An AGA 782 digital thermographic system with spatial and thermal resolution of +0.2mm and +0.2°C was used to continually record and analyze the measurements. Longitudinal incisions of 1 cm length were made in each vessel with a 6-0 prolene stay suture at each apex and the midpoint, forming two 5mm segments. A Sharplan CO 2 laser was used at an energy fluence of 1500 J/cm 2 , 150mw power, spot size of .00049 cm 2 and exposure of 5 seconds to induce fusion of each 0.5 cm of vessel wall. Argon fusion was accomplished with the HGM Argon laser using a 300 micron diameter fiber held 1 cm from the surface of the vessel, energy fluence of 570 J/cm 2 , 500mw power, spot size of 0.066cm 2 and total exposure of 75 seconds per 0.5cm length. Continuous irrigation of room temperature saline at 1 drop/second (approx. 3m1/min) was used during argon welding. With CO2 laser welding temperature increased quickly to its maximum (MAX=84.0, MEAN=60.7+ 9.8°C) which was maintained as the laser energy moved slowly (0.1cm/sec) along the vessel edges. In contrast the argon laser welding temperatures rose to a maximum (MAX=48.8, MEAN=45.1+2.7°C) and returned to a baseline temperature with each drop of saline. The thermal difference with these two laser wavelengths may bring about different welding mechanisms and provide an explanation for the increased incidence of thrombus aneurysm formation that has been reported in CO 2 laser fusion.