Randomised controlled trial on robot-assisted versus manual surgery for pucker peeling.

BACKGROUND: The aim was to explore the feasibility and safety of performing common surgical steps in epiretinal membrane (ERM) peeling using the Preceyes Surgical System (PSS). METHODS: In a tertiary centre, 15 pseudophakic patients with an idiopathic ERM were randomised to robot-assistance or manual surgery in a 2:1 ratio. In the robot-assisted group, the following steps were performed using PSS: (1) staining the internal limiting membrane (ILM), (2) removal of the dye, (3) creating an ILM flap, (4) completing the peeling, (5) holding a light pipe and (6) fluid-air exchange. Primary outcome measures were feasibility and safety. Secondary outcome measures were duration, best-corrected visual acuity (BCVA) and central retinal thickness (CRT). Moreover, the distance travelled by the instrument during peeling was assessed using motion tracking software. RESULTS: All steps performed with PSS were feasible with no clinical adverse events or complications. The surgical time was longer in the robot-assisted group (mean 56 min, SD = 12 vs. 24 min, SD = 5). During the study, the duration of robot-assisted surgeries decreased from 72 to 46 min. The distance travelled by the forceps was shorter in the robot-assisted group (mean 403 mm, SD = 186 vs. 550 mm, SD = 134). BCVA and CRT improved equally in both groups. CONCLUSIONS: This is the world's first randomised controlled trial on robotic surgery for ERM. Although more time-consuming, we found that several surgical steps were feasible with assistance of the PSS.

Human/robotic interaction: vision limits performance in simulated vitreoretinal surgery.

PURPOSE: Compare accuracy and precision in XYZ of stationary and dynamic tasks performed by surgeons with and without the use of a tele-operated robotic micromanipulator in a simulated vitreoretinal environment. The tasks were performed using a surgical microscope or while observing a video monitor. METHOD: Two experienced and two novice surgeons performed tracking and static tasks at a fixed depth with hand-held instruments on a Preceyes Surgical System R0.4. Visualization was through a standard microscope or a video display. The distances between the instrument tip and the targets (in µm) determined tracking errors in accuracy and precision. RESULTS: Using a microscope, dynamic or static accuracy and precision in XY (planar) movements were similar among test subjects. In Z (depth) movements, experience lead to more precision in both dynamic and static tasks (dynamic 35 ± 14 versus 60 ± 37 µm; static 27 ± 8 versus 36 ± 10 µm), and more accuracy in dynamic tasks (58 ± 35 versus 109 ± 79 µm). Robotic assistance improved both precision and accuracy in Z (1-3 ± 1 µm) in both groups. Using a video screen in combination with robotic assistance improved all performance measurements and reduced any differences due to experience. CONCLUSIONS: Robotics increases precision and accuracy, with greater benefit observed in less experienced surgeons. However, human control was a limiting factor in the achieved improvement. A major limitation was visualization of the target surface, in particular in depth. To maximize the benefit of robotic assistance, visualization must be optimized.

Release of experimental retinal vein occlusions by direct intraluminal injection of ocriplasmin.

PURPOSE: Retinal vein occlusions (RVO) are a major cause of vision loss in people aged 50 years and older. Current therapeutic options limit the consequences of RVO but do not eliminate the cause. Cannulation of the involved vessel and removal of the clot may provide a more permanent solution with a less demanding follow-up. However, cannulation of smaller retinal veins remains challenging. This paper explores the use of ocriplasmin (recombinant plasmin without its kringles) to clear RVO, using a robotic micromanipulator. METHODS: Branch RVO were induced in a porcine model with rose bengal followed by 532 nm endolaser to the superior venous branch of the optic nerve. The vein was cannulated proximal to the occlusion or beyond the first branching vessel from the obstruction. The vein was infused with a physiologic citric acid buffer solution (CAM) or CAM/ocriplasmin. The time of cannulation, number of attempts, and the ability to release the thrombus were recorded. RESULTS: Cannulation and infusion was possible in all the cases. The use of a micromanipulator allowed for a consistent cannulation of the retinal vein and positional stability allowed the vein to remain cannulated for up to 20 min. In none of the attempts (5/5) with CAM did the thrombus dissolve, despite repeat infusion/relaxation cycles. In 7/7 injections of CAM/ocriplasmin near to the point of obstruction, the clot started to dissolve within a few minutes of injection. An infusion, attempted beyond the first venous branch point proximal to the clot, was unsuccessful in 2/3 attempts. CONCLUSIONS: Ocriplasmin is effective in resolving RVO if injected close to the site of occlusion with the use of a micromanipulator.

Robotic Assisted Cannulation of Occluded Retinal Veins.

PURPOSE: To develop a methodology for cannulating porcine retinal venules using a robotic assistive arm after inducing a retinal vein occlusion using the photosensitizer rose bengal. METHODOLOGY: Retinal vein occlusions proximal to the first vascular branch point were induced following intravenous injection of rose bengal by exposure to 532nm laser light delivered by slit-lamp or endolaser probe. Retinal veins were cannulated by positioning a glass catheter tip using a robotically controlled micromanipulator above venules with an outer diameter of 80µm or more and performing a preset piercing maneuver, controlled robotically. The ability of a balanced salt (BSS) solution to remove an occlusion by repeat distention of the retinal vein was also assessed. RESULTS: Cannulation using the preset piercing program was successful in 9 of 9 eyes. Piercing using the micromanipulator under manual control was successful in only 24 of 52 attempts, with several attempts leading to double piercing. The best location for cannulation was directly proximal to the occlusion. Infusion of BSS did not result in the resolution of the occlusion. CONCLUSION: Cannulation of venules using a robotic microassistive arm can be achieved with consistency, provided the piercing is robotically driven. The model appears robust enough to allow testing of therapeutic strategies aimed at eliminating a retinal vein thrombus and its evolution over time.

Heparin coating of extracorporeal circuits inhibits contact activation during cardiac operations.

OBJECTIVE: Heparin coating reduces complement activation on the surface of extracorporeal circuits. In this study we investigated its effect on activation of the contact system in 30 patients undergoing coronary artery bypass grafting with the use of a heparin-coated (Duraflo II, Baxter Healthcare Corp., Edwards Division, Santa Ana, Calif.; n = 15) or an uncoated extracorporeal circuit (n = 15). METHODS: Plasma markers that reflect activation of contact (kallikrein-C1-inhibitor complexes), coagulation (prothrombin fragments F1 + 2), or fibrinolytic (plasmin-alpha 2-antiplasmin complexes) systems were determined before and during the operation. The generation of kallikrein-C1-inhibitor complexes was reduced by 62% (p = 0.06) after the onset of cardiopulmonary bypass and by 43% (p = 0.026) after the cessation of bypass in the group in which a heparin-coated circuit was used compared with the group in which the circuit was uncoated. Generation was reduced by 58% (p = 0.06) when the ratio of kallikrein-C1-inhibitor to prekallikrein after onset of bypass was considered. We detected significant increases in F1 + 2 levels in both groups and increases in plasmin-alpha 2-antiplasmin complexes in the heparin-coated group at cessation of bypass, but no intergroup differences were observed. Thus use of heparin-coated extracorporeal circuits during cardiac operations reduces formation of kallikrein-C1-inhibitor complexes when compared with use of uncoated circuits. The heparin coating is not accompanied by similar reductions in coagulation or fibrinolysis, suggesting that thrombin and plasmin formation during cardiopulmonary bypass occurs mainly independently of the contact system activation.

Heparin coating with aprotinin reduces blood activation during coronary artery operations.

BACKGROUND: This study was performed to evaluate whether the combination of heparin-coated extracorporeal circuits (ECC) and aprotinin treatment reduce blood activation during coronary artery operations. METHODS: Sixty patients were prospectively divided into two groups (heparin-coated ECC and uncoated ECC groups), which were comparable in terms of age, sex, left ventricular function, preoperative aspirin use and consequent intraoperative aprotinin use, number of grafts, duration of aortic cross-clamping, and duration of cardiopulmonary bypass. Blood activation was assessed at different times during cardiopulmonary bypass by determination of complement activation (C3 and C4 activation products C3b/c and C4b/c and terminal complement complex), leukocyte activation (elastase), coagulation (scission peptide fibrinopeptide 1 + 2), and fibrinolysis (D-dimers). RESULTS: Univariate analysis showed that heparin-coated ECC, under conditions of standard heparinization, did not reduce perioperative blood loss and need for transfusion. Heparin coating, however, reduced maximum values of C3b/c (446 +/- 212 nmol/L versus 632 +/- 264 nmol/L with uncoated ECC; p = 0.0037) and maximum C4b/c values (92 +/- 48 nmol/L versus 172 +/- 148 nmol/L with uncoated ECC; p = 0.0069). Levels of terminal complement complex, elastase, fibrinopeptide 1 + 2, and D-dimers were not significantly modified by the use of heparin-coated ECC. Multivariate analysis showed that the intergroup differences in maximum C3b/c and C4b/c values were more pronounced in women in part with high baseline values of C3b/c. We also found that aprotinin contributed to the reduction of maximum values of fibrinopeptide 1 + 2 and D-dimers, whereas heparin coating had no significant influence on these parameters. CONCLUSIONS: We found no evidence of combined properties of heparin-coated ECC and aprotinin in reducing complement activation, coagulation, and fibrinolysis. We therefore recommend use of both together to achieve maximal reduction of blood activation during cardiopulmonary bypass for coronary artery operations.