A new bipolar device for sealing and cutting: ex and in vivo studies for performance evaluation.

INTRODUCTION: A novel multipurpose bipolar radiofrequency instrument, the Erbe Dissector (EDS), which simultaneously seals and cuts tissue, was developed. Ex vivo sealing rate and time, burst pressure, jaw temperature and thermal spread were studied in porcine renal arteries. MATERIAL AND METHODS: In vivo, 13 surgical tasks were performed in two pigs: beside sealing rate and time, overall performance in sharp and blunt dissection, tissue sticking, hemostasis, precision, etc., were evaluated by four surgeons compared with ENSEAL G2 (EG2) using surveys on a Likert scale (1 = very poor; 5 = very good). RESULTS: Ex vivo, the EDS sealing rate was 91.7% (33/36 arteries) at an average sealing time of 2.1 s (range 1.7-2.8) and a burst pressure of 1040 ± 350 mmHg. The maximum jaw temperature was 87 ± 4 °C and the mean lateral thermal spread was 0.8 ± 0.2 mm. In vivo, the sealing rate for arteries and veins was 92.6% (50/54) and the median seal and cut time was 1.6 s (range: 1.3-2.9). The average EDS performance score across all tasks was 4.4 ± 0.6 Likert points. For five shared tasks, EDS was better than EG2 (4.4 ± 0.5 versus 3.4 ± 0.6 Likert points; p = 0.016). CONCLUSIONS: EDS seals and cuts arteries and veins rapidly with good safety and user-friendliness.

Risk assessment of neuromuscular stimulation by energy-based transurethral resection devices: an ex vivo test standard.

BACKGROUND: During transurethral resection of bladder tumours (TURB), radio-frequency (RF) currents can lead to adverse neuromuscular stimulation (NMS). Here we present a novel ex vivo method to determine the risk of RF generators and their bipolar TURB modes to cause NMS. We aimed to develop an experimental platform for safety evaluation of new RF generators and their modes with a newly established test standard, suitable for replacement or reduction of animal testing. METHODS: We tested four contemporary RF generators with their bipolar modes for TURB in saline. A two-stage ex vivo approach was pursued: First, we recorded voltages at possible positions of the obturator nerve behind a porcine bladder wall in a TURB model using 18 RF applications per generator. Second, these voltage records were used as stimuli to evoke nerve compound action potentials (CAPs) in isolated porcine axillary nerves. The NMS potential was defined as the ratio between the observed area under the CAPs and the theoretical CAP area at maximum response and a firing rate of 250 Hz, which would reliably induce tetanic muscle responses in most human subjects. The measurement protocol was tailored to optimise reproducibility of the obtained NMS potentials and longevity of the nerve specimens. RESULTS: As prerequisite for the clinical translation of our results, the robustness of our test method and reproducibility of the NMS potential are demonstrated with an excellent correlation (r = 0.93) between two sets of identical stimuli (n = 72 each) obtained from 16 nerve segments with similar diameters (4.2 ± 0.37 mm) in the nerve model. The RF generators differed significantly (p < 0.0001) regarding NMS potential (medians: 0-3%). CONCLUSIONS: Our test method is suitable for quantifying the NMS potential of different electrosurgical systems ex vivo with high selectivity at a reasonable degree of standardization and with justifiable effort. Our results suggest that the clinical incidence of NMS is considerably influenced by the type of RF generator. Future generations of RF generators take advantage from the proposed test standard through higher safety and less animal testing. Health professionals and treated patients will benefit most from improved RF surgery using generators with a low NMS risk.

Safety and effectiveness of a novel generator algorithm for bipolar vessel sealing: a randomised controlled chronic animal study.

BACKGROUND: Electrosurgical vessel sealers are gradually replacing conventional techniques such as ligation and clipping. Algorithms that control electrosurgical units (ESU), known as modes, are important for applications in different surgical disciplines. This chronic porcine animal study aimed to evaluate the safety and effectiveness of the novel thermoSEAL electrosurgical vessel sealing mode (TSM). The BiClamp® mode (BCM) of the renowned VIO® 300 D ESU served as control. BCM has been widely available since 2002 and has since been successfully used in many surgical disciplines. The TSM, for the novel VIO® 3 ESU, was developed to reduce sealing time and/or thermal lateral spread adjacent to the seal while maintaining clinical success rates. The primary aim of this study was to investigate the long-term and intraoperative seal quality of TSM. METHODS: The BiCision® device was used for vessel sealing with TSM and BCM in ten German Landrace pigs which underwent splenectomy and unilateral nephrectomy during the first intervention of the study. The seals were cut with the BiCision® knife. Ninety-nine arteries, veins and vascular bundles were chronically sealed for 5 or 21 days. Thereafter, during the second and terminal intervention of the study, 97 additional arteries and veins were sealed. The carotid arteries were used for histological evaluation of thermal spread. RESULTS: After each survival period, no long-term complications occurred with either mode. The intraoperative seal failure rates, i.e. vessel leaking or residual blood flow after the first sealing activation, were 2% with TSM versus 6% with BCM (p = 0.28). The sealing time was significantly shorter with TSM (3.5 ± 0.69 s vs. 7.3 ± 1.3 s, p < 0.0001). The thermal spread and burst pressure of arteries sealed with both modes were similar (p = 0.18 and p = 0.61) and corresponded to the histological evaluation. The measured tissue sticking parameter was rare with both modes (p = 0.33). Tissue charring did not occur. Regarding the cut quality, 97% of the seals were severed in the first and 3% in the second attempt (both with TSM and BCM). CONCLUSIONS: The novel TSM seals blood vessels twice as fast as the BCM while maintaining excellent tissue effect and clinical success rates. TRIAL REGISTRATION: Not applicable.

Colorectal Endoscopic Submucosal Dissection: Performance of a Novel Hybrid-Technology Knife in an Animal Trial.

Endoscopic submucosal dissection (ESD) was developed for the removal of benign and early malignant lesions in the gastrointestinal tract. We aimed to evaluate the performance and safety of a novel high-pressure waterjet-assisted ESD knife in colorectal applications. Six female German Landrace pigs with an average weight of 62 kg (range 60-65 kg) were used in this prospective, randomized, and controlled study. Twenty-four ESDs were performed by three endoscopists: Twelve each with the new Erbe HYBRIDknife® flex T-Type (HK-T) and the Olympus DualKnife® J (DK-J), including six rectal and six colonic ESDs per instrument. The order of performance was randomized regarding anatomic position and instrument. As the primary endpoint, ESD knife performance characteristics were combined and rated on a 5-point Likert scale, with 5 Likert points (LP) representing the best response (5 = very good). The HK-T was rated significantly better than the DK-J (4.7 LP versus 4.4 LP, p = 0.0295), mainly because of HK-T injection ability (5 LP versus 3 LP, p < 0.0001) and hemostasis (5 LP versus 4 LP, p = 0.0452). There was no difference in procedure time (HK-T: 35 min versus DK-J: 34 min, p = 0.8005), resection diameter (3.1 cm versus 2.8 cm, p = 0.3492), injection volume (41 mL versus 46 mL, p = 0.5633), and complication rates. HK-T is as effective as DK-J in colorectal ESD in terms of dissection quality but has better injection and hemostatic properties. The impact of these technical advantages on the ESD treatment of patients with large superficial colorectal lesions remains to be clinically verified.

Surgical smoke: modern mobile smoke evacuation systems improve occupational safety in the operating theatre.

OBJECTIVES: Evaluation of smoke capture efficiency of different mobile smoke evacuation devices with respect to volatile organic compounds and their noise emission. METHODS: Electrosurgical incisions were performed on fresh porcine liver in an operating room with vertical laminar flow. The generated surgical smoke was analysed with proton-transfer-reaction mass spectrometry with and without the use of a mobile smoke evacuation system consisting of a smoke evacuator machine, a suction hose and a handpiece. The inlet of the mass spectrometer was positioned 40 cm above the specimen. Various devices were compared: a hard plastic funnel, a flexible foam funnel, an on-tip integrated aspirator of an electrosurgical knife and a standard secretion suction (Yankauer). Also, sound levels were measured at a distance of 40 cm from the handpieces' inlet. RESULTS: The smoke capture efficiency of the secretion suction was only 53%, while foam funnel, plastic funnel and integrated aspirator were all significantly more effective with a clearance of 95%, 91% and 91%, respectively. The mean sound levels were 68 and 59 A-weighted decibels with the plastic and foam funnel, respectively, 66 A-weighted decibels with the integrated aspirator and 63 A-weighted decibels with the secretion suction. CONCLUSIONS: Carcinogenic, mutagenic and reprotoxic volatile organic compounds in surgical smoke can be efficiently reduced by mobile smoke evacuation system, providing improved protection for medical personnel. Devices specifically designed for smoke evacuation are more efficient than standard suction tools. Noise exposure for the surgeon was lowest with the flexible foam funnel and higher with the other handpieces tested.

Initiation of smooth-pursuit eye movements by real and illusory contours.

It is well established that elementary motion detectors are only able to code for the movement of a contour perpendicular to its orientation. This shortcoming explains why the initial direction of smooth-pursuit eye movements is directed orthogonal to the orientation of a moving contour independent of its veridical direction of motion. Here, we replicated this finding and asked whether this directional error can be reduced by subjects' prediction of upcoming target moving direction and whether this directional error also occurs during tracking of an illusory contour. Our results show that prediction did not abolish the directional error, it was only slightly reduced. On the other hand, the directional error was considerably diminished during pursuit initiation towards illusory contours and most likely reflected the amount of real stimulation defining the specific illusory contour. We conclude that pursuit initiation is driven by raw retinal image motion signals, which are not yet processed for figure completion.

Visual stability and the motion aftereffect: a psychophysical study revealing spatial updating.

Eye movements create an ever-changing image of the world on the retina. In particular, frequent saccades call for a compensatory mechanism to transform the changing visual information into a stable percept. To this end, the brain presumably uses internal copies of motor commands. Electrophysiological recordings of visual neurons in the primate lateral intraparietal cortex, the frontal eye fields, and the superior colliculus suggest that the receptive fields (RFs) of special neurons shift towards their post-saccadic positions before the onset of a saccade. However, the perceptual consequences of these shifts remain controversial. We wanted to test in humans whether a remapping of motion adaptation occurs in visual perception.The motion aftereffect (MAE) occurs after viewing of a moving stimulus as an apparent movement to the opposite direction. We designed a saccade paradigm suitable for revealing pre-saccadic remapping of the MAE. Indeed, a transfer of motion adaptation from pre-saccadic to post-saccadic position could be observed when subjects prepared saccades. In the remapping condition, the strength of the MAE was comparable to the effect measured in a control condition (33±7% vs. 27±4%). Contrary, after a saccade or without saccade planning, the MAE was weak or absent when adaptation and test stimulus were located at different retinal locations, i.e. the effect was clearly retinotopic. Regarding visual cognition, our study reveals for the first time predictive remapping of the MAE but no spatiotopic transfer across saccades. Since the cortical sites involved in motion adaptation in primates are most likely the primary visual cortex and the middle temporal area (MT/V5) corresponding to human MT, our results suggest that pre-saccadic remapping extends to these areas, which have been associated with strict retinotopy and therefore with classical RF organization. The pre-saccadic transfer of visual features demonstrated here may be a crucial determinant for a stable percept despite saccades.