David R. C. James

Is minimally invasive surgery beneficial in the management of esophageal cancer? A meta-analysis

IntroductionOpen esophagectomy for cancer is a major oncological procedure, associated with significant morbidity and mortality. Recently, thoracoscopic procedures have offered a potentially advantageous alternative because of less operative trauma compared with thoracotomy. The aim of this study was to utilize meta-analysis to compare outcomes of open esophagectomy with those of minimally invasive esophagectomy (MIE) and hybrid minimally invasive esophagectomy (HMIE).MethodsLiterature search was performed using Medline, Embase, Cochrane Library, and Google Scholar databases for comparative studies assessing different techniques of esophagectomy. A random-effects model was used for meta-analysis, and heterogeneity was assessed. Primary outcomes of interest were 30-day mortality and anastomotic leak. Secondary outcomes included operative outcomes, other postoperative outcomes, and oncological outcomes in terms of lymph nodes retrieved.ResultsA total of 12 studies were included in the analysis. Studies included a total of 672 patients for MIE and HMIE, and 612 for open esophagectomy. There was no significant difference in 30-day mortality; however, MIE had lower blood loss, shorter hospital stay, and reduced total morbidity and respiratory complications. For all other outcomes, there was no significant difference between the two groups.ConclusionMinimally invasive esophagectomy is a safe alternative to the open technique. Patients undergoing MIE may benefit from shorter hospital stay, and lower respiratory complications and total morbidity compared with open esophagectomy. Multicenter, prospective large randomized controlled trials are required to confirm these findings in order to base practice on sound clinical evidence.

Polycyclic motion history of some Gulf Coast growth faults from high-resolution displacement analysis

This paper describes some simple graphical techniques for analyzing the kinematic evolution of growth faults and presents a case study of the late Pleistocene–recent history of a group of 17 faults from offshore Texas. Throw versus depth plots derived from depth-converted high-resolution seismic data were used to define growth histories. The faults exhibit polycyclic kinematic behavior, with at least three cycles of active fault growth separated by periods of inactivity. This cyclic behavior correlates broadly with three transgressive-regressive cycles along this part of the Gulf Coast. In detail, however, we find that activity of closely spaced faults in the array can either be in phase or out of phase with neighboring faults. This complex group behavior is attributed to the geometry of the detachment surface, pore-fluid pressure distribution, loading, and friction. This study demonstrates that although a general correlation with sediment loading may exist, individual fault activity is unlikely to correlate with periods of maximum sediment accumulation.

The role of robotic assisted laparoscopy for oesophagogastric oncological resection; an appraisal of the literature.

The introduction of surgical robotics to the field of surgical oncology brings with it an expectation not only of improved vision, instrumentation, and precision but also as a result, a potential for improved oncological outcomes. The current interest in the field of oesophagogastric oncology is explored in this review together with the benefits, real and potential, that robotic assistance offers surgical cancer resection as well as some of the limiting factors which may be hampering its uptake into current surgical practice. A systematic review of all the published literature up until April 2010 was examined across the field of esophageal and gastric cancer resection. A quantitative assessment of the oncological, operative, and functional outcomes was determined from each procedure. The level of evidence behind the results was determined using the Oxford Centre for Evidence-based Medicine Levels of Evidence; Therapy and Prevention. Three hundred and five cases from 19 independent studies were included for review. Nine studies explored the outcomes from robotic-assisted esophagectomy and eight, the robotic-assisted gastrectomy. Two articles included small case series of both procedures. The level of evidence was predominantly based on case series or expert opinion (Level 4 or 5) with only three unmatched or poorly matched comparative trials (Level 4) with no randomized trials evident. Improved operative outcomes and hospital stays were demonstrated with a reduction of 2 days when the robotic-assisted gastrectomy technique was employed compared with the open. No improvement in oncological outcomes could be identified with the use of the robot for either oesophageal or gastric cancer resection; however, in terms of short-term oncological outcomes, these were at least equivalent to the open approach for oesophageal cancer and early stage gastric cancer. Robotic-assisted laparoscopic surgery is a feasible technique to use to perform a safe and oncologically sound resection for oesophageal and early gastric cancer. Operative benefits appear to be encouragingly similar to the laparoscopic approach with some demonstration of improvement over the open technique despite a prolonged operative time. However, the level of evidence is suboptimal and more randomized controlled trials and long-term survival studies within a framework of measured and comparable outcomes is required.

Quality control and assurance in functional near infrared spectroscopy (fNIRS) experimentation

Functional near infrared spectroscopy (fNIRS) is a rapidly developing neuroimaging modality for exploring cortical brain behaviour. Despite recent advances, the quality of fNIRS experimentation may be compromised in several ways: firstly, by altering the optical properties of the tissues encountered in the path of light; secondly, through adulteration of the recovered biological signals (noise) and finally, by modulating neural activity. Currently, there is no systematic way to guide the researcher regarding these factors when planning fNIRS studies. Conclusions extracted from fNIRS data will only be robust if appropriate methodology and analysis in accordance with the research question under investigation are employed. In order to address these issues and facilitate the quality control process, a taxonomy of factors influencing fNIRS data have been established. For each factor, a detailed description is provided and previous solutions are reviewed. Finally, a series of evidence-based recommendations are made with the aim of improving consistency and quality of fNIRS research.

Synthesis of a Novel Fused Thiophene-thieno[3,2-b]thiophene-thiophene Donor Monomer and Co-polymer for Use in OPV and OFETs

The synthesis of a novel fused hexacyclic electron rich monomer incorporating thieno[3,2-b]thiophene is reported and characterized by single crystal X-ray diffraction. Suzuki co-polymerization with benzothiadiazole (BT) afforded a novel low band-gap polymer P4TBT with high molecular weights and good solution processability. Bulk heterojunction solar cell devices using the P4TBT and [70]PCBM gave power conversion efficiencies of 2.5%. Top-gate, bottom-contact field effect transistors (FETs) using P4TBT displayed high hole mobilities of 0.07 cm(2) · Vs(-1) demonstrating the suitability of the novel monomer and polymer for use in high performing organic electronic devices.

Multispectral image alignment using a three channel endoscope in vivo during minimally invasive surgery.

Sequential multispectral imaging is an acquisition technique that involves collecting images of a target at different wavelengths, to compile a spectrum for each pixel. In surgical applications it suffers from low illumination levels and motion artefacts. A three-channel rigid endoscope system has been developed that allows simultaneous recording of stereoscopic and multispectral images. Salient features on the tissue surface may be tracked during the acquisition in the stereo cameras and, using multiple camera triangulation techniques, this information used to align the multispectral images automatically even though the tissue or camera is moving. This paper describes a detailed validation of the set-up in a controlled experiment before presenting the first in vivo use of the device in a porcine minimally invasive surgical procedure. Multispectral images of the large bowel were acquired and used to extract the relative concentration of haemoglobin in the tissue despite motion due to breathing during the acquisition. Using the stereoscopic information it was also possible to overlay the multispectral information on the reconstructed 3D surface. This experiment demonstrates the ability of this system for measuring blood perfusion changes in the tissue during surgery and its potential use as a platform for other sequential imaging modalities.

The ergonomics of natural orifice translumenal endoscopic surgery (NOTES) navigation in terms of performance, stress, and cognitive behavior

BACKGROUND The evolution toward minimally invasive surgery and subsequently to natural orifice translumenal endoscopic surgery (NOTES) poses challenges to the surgeon in terms of increased task complexity requiring greater visuospatial and navigational ability. Neuroergonomics is the study of the brain and behavior at work, and establishing the baseline cortical response for NOTES procedures will help to ascertain whether technological innovation such as navigational aids can alleviate the task-induced cognitive burden. The aims of the current study are to characterize the impact of navigation within a NOTES environment on the subject in terms of (1) performance, (2) stress, (3) prefrontal cortical activity, and (4) how this is influenced by expertise. METHODS In all, 29 subjects were assessed for performance, stress response, and prefrontal cortical activity during a NOTES navigational task within a validated NOTES simulator. RESULTS Experts performed significantly better than novices (P < .05). Expertise was not a predictor for overall changes in prefrontal cortical activity. The differences between experts and novices were modulated by the location of prefrontal cortical activity, with experts demonstrating more pronounced lateral prefrontal cortical activation compared with novices. Stress was not an independent predictor of changes in prefrontal cortical hemodynamics. CONCLUSION This study is the first to characterize the performance, stress, and neurocognitive behavior associated with natural orifice translumenal endoscopic surgery navigation. The results indicate the relevance of visuospatial centers in successful task execution, and they serve as a baseline within the neuroergonomic paradigm for investigating performance-enhancing technology.

The impact of expert visual guidance on trainee visual search strategy, visual attention and motor skills

Minimally invasive and robotic surgery changes the capacity for surgical mentors to guide their trainees with the control customary to open surgery. This neuroergonomic study aims to assess a “Collaborative Gaze Channel” (CGC); which detects trainer gaze-behavior and displays the point of regard to the trainee. A randomized crossover study was conducted in which twenty subjects performed a simulated robotic surgical task necessitating collaboration either with verbal (control condition) or visual guidance with CGC (study condition). Trainee occipito-parietal (O-P) cortical function was assessed with optical topography (OT) and gaze-behavior was evaluated using video-oculography. Performance during gaze-assistance was significantly superior [biopsy number: (mean ± SD): control = 5.6 ± 1.8 vs. CGC = 6.6 ± 2.0; p < 0.05] and was associated with significantly lower O-P cortical activity [ΔHbO2 mMol × cm [median (IQR)] control = 2.5 (12.0) vs. CGC 0.63 (11.2), p < 0.001]. A random effect model (REM) confirmed the association between guidance mode and O-P excitation. Network cost and global efficiency were not significantly influenced by guidance mode. A gaze channel enhances performance, modulates visual search, and alleviates the burden in brain centers subserving visual attention and does not induce changes in the trainee’s O-P functional network observable with the current OT technique. The results imply that through visual guidance, attentional resources may be liberated, potentially improving the capability of trainees to attend to other safety critical events during the procedure.

Synthesis and photo-induced charge separation of confined conjugation length phenylene vinylene-based polymers

We report the synthesis and photophysics of four confined chromophore phenylene vinylene (PPV)-based polymers where PPV-type trimer chromophores are linked by alkyl ether chains of increasing length (PT3–PT6). These confined chromophore polymers were blended in a 1 : 1 w/w ratio with the fullerene derivative PCBM and the photoinduced charge-separation properties compared to that of a fully conjugated polymer analogue (alt-co-MEH-PPV). Fluorescence from all polymers is quenched in the presence of PCBM and transient absorption measurements confirm the presence of polymer polarons arising from charge transfer from the polymer to the PCBM acceptor. The polaron decay kinetics of all the blend films were similar but the yields of polarons for the confined conjugation length polymers were lower than for alt-co-MEH-PPV:PCBM. These observations suggest that many of the initially formed radical ion pairs for the confined length polymers are unable to fully charge dissociate and undergo fast geminate recombination.

Disinfection of the Access Orifice in NOTES: Evaluation of the Evidence Base.

Introduction. Appropriate prevention of infection is a key area of research in natural orifice translumenal endoscopic surgery (NOTES), as identified by the Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR). Methods. A review of the literature was conducted evaluating the evidence base for access orifice preparation/treatment in NOTES procedures in the context of infectious complications. Recommendations based on the Oxford Centre for Evidence-Based Medicine guidelines were made. Results. The most robust evidence includes several experimental randomised controlled trials assessing infectious complications in the transgastric approach to NOTES. Transvaginal procedures are long established for accessing the peritoneal cavity following disinfection with antiseptic. Only experimental case series for transcolonic and transvesical approaches are described. Conclusion. Grade C recommendation requiring no preoperative preparation can be made for the transgastric approach. Antiseptic irrigation is recommended for transvaginal (grade C) NOTES access, as is current practice. Further human trials need to be conducted to corroborate the current evidence base for transgastric closure. It is important that future trials are conducted in a methodologically robust fashion, with emphasis on clinical outcomes and standardisation of enterotomy closure and postoperative therapy.