Aaron Barnes

A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery.

OBJECTIVES To introduce and evaluate the infusion and aspiration rates and operative times of the 25-gauge transconjunctival sutureless vitrectomy system (TSV) DESIGN: In vitro experimental and comparative interventional study. PARTICIPANTS AND CONTROLS Twenty eyes of 20 patients underwent a variety of vitreoretinal procedures using the 25-gauge TSV, including idiopathic epiretinal membrane (n = 10), macular hole (n = 4), rhegmatogenous retinal detachment (n = 3), branch retinal vein occlusion (n = 2), diabetic vitreous hemorrhage (n = 1), and 20 cases similar in diagnosis and severity were matched to provide comparison between duration of individual portions of the surgical procedures with the existing 20-gauge vitrectomy system. METHODS Description of the 25-gauge TSV is provided; infusion and aspiration rates of the 25-gauge and standard 20-gauge vitrectomy system were measured in vitro using balanced saline solution and porcine vitreous for several levels of aspirating power and bottle height, and operating times of individual portions of surgical procedures were measured for the 25-gauge and 20-gauge vitrectomy system. MAIN OUTCOME MEASURES Infusion, aspiration rates, and operative times of the 20-gauge and 25-gauge vitrectomy system. RESULTS Infusion and aspiration rates of the 25-gauge TSV system were reduced by an average of 6.9 and 6.6 times, respectively, compared with the 20-gauge system when balanced saline solution was used. The average flow rate of the Storz 25-gauge cutter (at 500 mmHg, 1500 cuts per minute [cpm]) was 40% greater than that of the 20-gauge pneumatic cutter (at 250 mmHg, 750 cpm) but about 2.3 times less than the 20-gauge high-speed cutter (at 250 mmHg, 1500 cpm). Mean total operative time was significantly greater for the 20-gauge high-speed cutter (26 minutes, 7 seconds) than for the 25-gauge vitrectomy system (17 minutes, 17 seconds) (P = 0.011). CONCLUSIONS Although the infusion and aspiration rates of the 25-gauge instruments are lower than those for the 20-gauge high-speed vitrectomy system, the use of 25-gauge TVS may effectively reduce operative times of select cases that do not require the full capability of conventional vitrectomy.

Initial experience using the transconjunctival sutureless vitrectomy system for vitreoretinal surgery

OBJECTIVE To describe the initial experience and to evaluate the safety and feasibility of using the 25-gauge Transconjunctival Sutureless Vitrectomy System (TSV) for a variety of vitreoretinal procedures. DESIGN Retrospective review of a consecutive interventional case series. PARTICIPANTS Thirty-five eyes of 33 patients, including cases of idiopathic epiretinal membrane (12 cases), retinal detachment (6 cases), macular hole (5 cases), branch retinal vein occlusion (4 cases), retinopathy of prematurity (4 cases), persistent diabetic macular edema (1 case), diabetic vitreous hemorrhage (1 case), retained lens material after cataract extraction (1 case), and Norrie disease (1 case). INTERVENTION All patients underwent surgery using the 25-gauge TSV. MAIN OUTCOME MEASURES Intraocular pressure, visual acuity, and postoperative complications. RESULTS The median preoperative intraocular pressure was 16 mmHg (range, 10-21 mmHg), whereas the median intraocular pressure on the first postoperative day was 12 mmHg (range, 6-28 mmHg). The median intraocular pressure at 1 week and 1 month were both 16 mmHg (range, 10-30 mmHg). Overall, the median preoperative visual acuity was 20/100 (range, 20/30 to hand motions), and the median postoperative visual acuity after a mean follow-up of 14 weeks (range, 1-60 weeks) was 20/60 (range, 20/20-20/150). One eye developed a postoperative retinal detachment. CONCLUSIONS The 25-gauge TSV seems to be practical and safe for a variety of vitreoretinal procedures. The concept of transconjunctival surgery has the potential to increase the efficiency of a variety of vitreoretinal surgeries and possibly hasten the postoperative recovery and outcomes in several conditions by simplifying the surgical procedure; minimizing surgically induced trauma; and decreasing the convalescence period, the operating time, and the postoperative inflammatory response.

An automated system for precise percutaneous access of the renal collecting system

Percutaneous surgical procedures are rapidly growing in popularity as they significantly reduce patient morbidity and recovery time when compared to more traditional open techniques. However, percutaneous procedures are often difficult. Percutaneous renal surgery is one example. Gaining access to the renal collecting system requires targeting of a specific calyx while avoiding critical internal structures and requires experience in the interpretation of radiographic images. Currently, this procedure is essentially done manually by trial and error. We present a system which automates the task of image-guided percutaneous needle placement. It is generally applicable to procedures for which the precision and accuracy of a percutaneous needle insertion is of primary concern. It can also be used, with minor modification, as a sub-component of larger systems for more involved procedures, for instance, percutaneous treatment of liver cancer [5]. A prototype system has been implemented, and we present validation of its applicability to renal access with in vitro, ex vivo, and in situ studies. Additionally, we discuss what work remains on the path to a complete system.

Vitreous dynamics: vitreous flow analysis in 20-, 23-, and 25-gauge cutters.

Purpose: To evaluate porcine vitreous flow and balanced saline solution (BSS) flow rates in different vitrectomy systems. Methods: Porcine vitreous was obtained within 24 hours of slaughter. A high-speed (2 samples/s) balance, precise to 0.01 g, was used. Variable cut rates and vacuum pressures were analyzed in vitreous and BSS. The vitreous was labeled with glass microspheres and triamcinolone acetonide. A high-speed (400 frames/s) camera was used to record cutting for each condition. Results: For all cutters, there was no vitreous flow at zero cut rates (off). In 25-gauge cutters, at 500 mmHg of vacuum, the electric cutter produced higher average flow rates at high cut rates (600 cpm, 0.004 mL/s, and 1500 cpm, 0.013 mL/s) than pneumatic, which demonstrated a decreased flow at speeds higher than 1000 cpm (1000 cpm, 0.015 mL/s, and 1500 cpm, 0.006 mL/s). The percentage of vitreous flow rate/BSS flow rate in different aspiration and cut rates showed an ascending curve. This demonstrates evidence of flow obstruction in 25- (all cut rates), 23- (all cut rates), and 20-gauge (all cut rates). Flow obstruction and surge movements were seen in the high-speed videos. Conclusions: The vitrectomy systems each illustrate different performances of vitreous removal. The physical characteristics of vitreous resulted in nonuniform flow in all vitreous cutters.

A Steady-Hand Robotic System for Microsurgical Augmentation

This paper reports the development of a robotic system designed to extend a human’s ability to perform small-scale (sub-millimeter) manipulation tasks requiring human judgement, sensory integration and hand-eye coordination. Our novel approach, which we call “steady hand” micromanipulation, is for tools to be held simultaneously both by the operator’s hand and a specially designed actively controlled robot arm. The robot’s controller senses forces exerted by the operator on the tool and by the tool on the environment, and uses this information in various control modes to provide smooth, tremor-free precise positional control and force scaling. Our goal is to develop a manipulation system with the precision and sensitivity of a machine, but with the manipulative transparency and immediacy of handheld tools for tasks characterized by compliant or semi-rigid contacts with the environment.

A system for percutaneous delivery of treatment with a fluoroscopically-guided robot

This manuscript discusses a prototype image-guided robotic system that is currently under development at The Johns Hopkins University. This system is intended to allow percutaneous delivery of surgical devices as well as therapeutic agents to soft tissue and bone lesions. The proposed system has many potential applications including the treatment of liver cancer, which is an attractive application of the technology.

An Augmentation System for Fine Manipulation

Augmented surgical manipulation tasks can be viewed as a sequence of smaller, simpler steps driven primarily by the surgeon’s input. These steps can be abstracted as controlled interaction of the tool/end-effector with the environment. The basic research problem here is performing a sequence of control primitives. In computing terms, each of the primitives is a predefined computational routine (e.g. compliant motion or some other “macro”) with initiation and termination predicates. The sequencing of these primitives depends upon user control and effects of the environmental interaction. We explore a sensor driven system to perform simple manipulation tasks. The system is composed of a core set of “safe” system states and task specific states and transitions. Using the “steady hand” robot as the experimental platform we investigate using such a system.

Performance of Robotic Augmentation in Microsurgery-Scale Motions

This paper is part of the development process of a microsurgical “cooperating” assistant. To evaluate its applicability to augment fine surgical motions, we test precision and operator perception in simple microsurgical scale pick and place motions. Such motions are common in microsurgical procedures (e.g. micro-vascular anastomosis). The experiments test the users’ ability to position a common surgical tool to 250, 200 and 150 micrometer accuracy. These experiments were performed using two test platforms. The new “steady hand” robot designed for microsurgery and the LARS robot (a laparoscopic camera holding robot) adapted for this purpose. Comparative results for several parameters including time, success rate, error rate, number of attempts are included. Comparison of performance of the two robots for these tasks is also included. The results support our claim that the new “steady hand” robot augments human performance for microsurgery-scale motion.

A Testbed System for Robotically Assisted Percutaneous Pattern Therapy

This paper presents a second generation prototype image-guided robotic system for percutaneous delivery of surgical devices and therapeutic agents, with potential applications in the treatment of liver cancer and other malignancies. The system is intended to deliver these devices and therapies more consistently and accurately than a physician can achieve freehand. This capability will permit the treatment of smaller lesions, will enable the physician to better achieve optimized patterns of therapy distribution, and will allow for more rapid re-targeting for multiple lesions. The system will allow treatment of patients for whom surgery is contraindicated and could potentially replace major surgery, reducing patient morbidity and mortality, as well as the cost of treatment. The new prototype system uses new, modular hardware and software components, which improve its accuracy, usability, and flexibility as compared to the first generation prototype. Techniques for image processing, both in 2D and 3D images, planning, and fiducial registration have also been developed. In vitro, the system achieves submillimetric accuracy in the placement of simulated treatment devices from a preoperative plan generated from 3D imagery. Some initial in vivo considerations have also been addressed, and work is ongoing in this area.

Human vs robotic organ retraction during laparoscopic Nissen fundoplication.

AbstractBackground: Advances in technique and instrumentation have enabled surgeons to perform an increasing number of complicated procedures through laparoscopy. However, these efforts have often been compromised by the exertion of excessive force when anatomical structures are retracted to create a clear view of the anatomy. Here, we present a comparative study of human and robotic performance in force-controlled organ retraction during laparoscopic Nissen fundoplication (LNF). Methods: Six female pigs (20–25 kg) were anesthetized, intubated, and placed on mechanical ventilation; pneumoperitoneum (13 mmHg CO2) was established. A force-sensing retractor (FSR) was constructed to record the forces applied in retracting the stomach during dissection of the esophageal hiatus. The FSR was calibrated using known forces and then operated by either human alone or robot under human guidance using the FSR data. The esophageal hiatus was visualized and dissected, and LNF was completed. Results: Less force was needed for robotic (74.3 ± 10.5 g; mean ± standard deviation) than for human (108.9 ± 34.3 g) retraction (p= 0.007) to obtain an optimal view of the esophageal hiatus. No significant differences were observed for retraction setup time (robot, 14.3 ± 0.8 min; human, 13.7 ± 9.9 min; mean ± SD) or hiatal dissection time (robot, 14.0 ± 3.0 min; human, 14.0 ± 6.1 min; mean ± SD). Conclusions: These preliminary results illustrate our continuing effort to develop and evaluate an automated surgical assistant for laparoscopy. As more personnel-intensive advanced laparoscopic procedures are performed, robotic retraction is likely to offer a superior alternative to human retraction; it minimizes the forces exerted on the organs while maintaining excellent anatomical view.