Satisfaction of surgeons with the current state of training in minimally invasive surgery: a survey among German surgeons.

BACKGROUND: Minimally invasive surgery (MIS) requires intense education and training with structured supervision and feedback. However, a standardized training structure is lacking in Germany. This nationwide survey aimed to assess the current state of minimally invasive surgery (MIS) training and factors impacting surgeons' satisfaction. METHODS: Between July and October 2021, an online survey was conducted among general, abdominal, and thoracic surgeons in Germany. The survey collected data on department size, individual operative experience, availability of MIS training equipment and curricula, and individual satisfaction with training. A linear regression analysis was conducted to investigate factors influencing the surgeons' satisfaction with the MIS training. RESULTS: A total of 1008 surgeons participated in the survey, including residents (26.1%), fellows (14.6%), attendings (43.8%), and heads of departments (15.2%). Of the respondents, 57.4% reported having access to MIS training equipment, 29.8% and 26% had a curriculum for skills lab MIS training and intraoperative MIS training, respectively. In multivariate linear regression analysis, strongest predictors for surgeons' satisfaction with skills lab MIS training and intraoperative training were the availability of respective training curricula (skills lab: ß 12.572; p < 0.001 & intraoperative: ß 16.541; p < 0.001), and equipment (ß 5.246; p = 0.012 & ß 4.295; p = 0.037), and experience as a first surgeon in laparoscopy (ß 12.572; p < 0.001 & ß 3.748; p = 0.007). Additionally, trainees and teachers differed in their satisfaction factors. CONCLUSION: Germany lacks standardized training curricula and sufficient access to MIS training equipment. Trainees and teachers have distinct factors influencing their satisfaction with MIS training. Standardized curricula, equipment accessibility, and surgical experience are crucial for improving surgeons' satisfaction with training.

Can you feel the force just right? Tactile force feedback for training of minimally invasive surgery-evaluation of vibration feedback for adequate force application.

BACKGROUND: Tissue handling is a crucial skill for surgeons and is challenging to learn. The aim of this study was to develop laparoscopic instruments with different integrated tactile vibration feedback by varying different tactile modalities and assess its effect on tissue handling skills. METHODS: Standard laparoscopic instruments were equipped with a vibration effector, which was controlled by a microcomputer attached to a force sensor platform. One of three different vibration feedbacks (F1: double vibration > 2 N; F2: increasing vibration relative to force; F3: one vibration > 1.5 N and double vibration > 2 N) was applied to the instruments. In this multicenter crossover trial, surgical novices and expert surgeons performed two laparoscopic tasks (Peg transfer, laparoscopic suture, and knot) each with all the three vibration feedback modalities and once without any feedback, in a randomized order. The primary endpoint was force exertion. RESULTS: A total of 57 subjects (15 surgeons, 42 surgical novices) were included in the trial. In the Peg transfer task, there were no differences between the tactile feedback modalities in terms of force application. However, in subgroup analysis, the use of F2 resulted in a significantly lower mean-force application (p-value = 0.02) among the student group. In the laparoscopic suture and knot task, all participants exerted significantly lower mean and peak forces using F2 (p-value < 0.01). These findings remained significant after subgroup analysis for both, the student and surgeon groups individually. The condition without tactile feedback led to the highest mean and peak force exertion compared to the three other feedback modalities. CONCLUSION: Continuous tactile vibration feedback decreases the mean and peak force applied during laparoscopic training tasks. This effect is more pronounced in demanding tasks such as laparoscopic suturing and knot tying and might be more beneficial for students. Laparoscopic tasks without feedback lead to increased force application.

Impact of dehydration on laparoscopic performance: a prospective, open-label, randomized cross-over trial.

INTRODUCTION: During laparoscopic surgery, surgeons may experience prolonged periods without fluid intake, which might impact surgical performance, yet there are no objective data investigating this issue. Therefore, the aim of this study was to elucidate the effect of prolonged dehydration on laparoscopic surgical performance and tissue handling. METHODS: A total of 51 laparoscopic novices participated in a single-center, open-label, prospective randomized cross-over trial. All participants were trained to proficiency using a standardized laparoscopic training curriculum. Afterward, all participants performed four different laparoscopic tasks twice, once after 6 h without liquid intake (dehydrated group) and once without any restrictions (control group). Primary endpoints were tissue handling defined by force exertion, task time, and error rate. The real hydration status was assessed by biological parameters, like heart rate, blood pressure, and blood gas analysis. RESULTS: 51 laparoscopic novices finished the curriculum and completed the tasks under both hydrated and dehydrated conditions. There were no significant differences in mean non-zero and peak force between the groups. However, dehydrated participants showed significantly slower task times in the Peg transfer task (hydrated: 139.2 s vs. dehydrated: 147.9 s, p = 0.034) and more errors regarding the precision in the laparoscopic suture and knot task (hydrated: 15.7% accuracy rate vs. dehydrated: 41.2% accuracy rate, p < 0.001). CONCLUSION: Prolonged periods of dehydration do not appear to have a substantial effect on the fundamental tissue handling skills in terms of force exertion among surgical novices. Nevertheless, the observed impact on speed and precision warrants attention.

The development of tissue handling skills is sufficient and comparable after training in virtual reality or on a surgical robotic system: a prospective randomized trial.

BACKGROUND: Virtual reality is a frequently chosen method for learning the basics of robotic surgery. However, it is unclear whether tissue handling is adequately trained in VR training compared to training on a real robotic system. METHODS: In this randomized controlled trial, participants were split into two groups for "Fundamentals of Robotic Surgery (FRS)" training on either a DaVinci VR simulator (VR group) or a DaVinci robotic system (Robot group). All participants completed four tasks on the DaVinci robotic system before training (Baseline test), after proficiency in three FRS tasks (Midterm test), and after proficiency in all FRS tasks (Final test). Primary endpoints were forces applied across tests. RESULTS: This trial included 87 robotic novices, of which 43 and 44 participants received FRS training in VR group and Robot group, respectively. The Baseline test showed no significant differences in force application between the groups indicating a sufficient randomization. In the Midterm and Final test, the force application was not different between groups. Both groups displayed sufficient learning curves with significant improvement of force application. However, the Robot group needed significantly less repetitions in the three FRS tasks Ring tower (Robot: 2.48 vs. VR: 5.45; p < 0.001), Knot Tying (Robot: 5.34 vs. VR: 8.13; p = 0.006), and Vessel Energy Dissection (Robot: 2 vs. VR: 2.38; p = 0.001) until reaching proficiency. CONCLUSION: Robotic tissue handling skills improve significantly and comparably after both VR training and training on a real robotic system, but training on a VR simulator might be less efficient.

Preoperative anaemia in distal pancreatectomy: a propensity-score matched analysis.

BACKGROUND: Preoperative anaemia is a prevalent morbidity predictor that adversely affects short- and long-term outcomes of patients undergoing surgery. This analysis aimed to investigate preoperative anaemia and its detrimental effects on patients after distal pancreatectomy. MATERIAL AND METHODS: The present study was a propensity-score match analysis of 286 consecutive patients undergoing distal pancreatectomy. Patients were screened for preoperative anaemia and classified according to WHO recommendations. The primary outcome measure was overall morbidity. The secondary endpoints were in-hospital mortality and rehospitalization. RESULTS: The preoperative anaemia rate before matching was 34.3% (98 patients), and after matching a total of 127 patients (non-anaemic 42 vs. anaemic 85) were included. Anaemic patients had significantly more postoperative major complications (54.1% vs. 23.8%; p < 0.01), a higher comprehensive complication index (26.2 vs. 4.3; p < 0.01), and higher in-hospital mortality rate (14.1% vs. 2.4%; p = 0.04). Multivariate regression analysis confirmed these findings and identified preoperative anaemia as a strong independent risk factor for postoperative major morbidity (OR 4.047; 95% CI: 1.587-10.320; p < 0.01). CONCLUSION: The current propensity-score matched analysis strongly considered preoperative anaemia as a risk factor for major complications following distal pancreatectomy. Therefore, an intense preoperative anaemia workup should be increasingly prioritised.

Differences in Physicians' Ratings of Work Stressors and Resources Associated With Digital Transformation: Cross-Sectional Study.

BACKGROUND: The emergence of the COVID-19 pandemic rapidly accelerated the need and implementation of digital innovations, especially in medicine. OBJECTIVE: To gain a better understanding of the stress associated with digital transformation in physicians, this study aims to identify working conditions that are stress relevant for physicians and differ in dependence on digital transformation. In addition, we examined the potential role of individual characteristics (ie, age, gender, and actual implementation of a digital innovation within the last 3 years) in digitalization-associated differences in these working conditions. METHODS: Cross-sectional web-based questionnaire data of 268 physicians (mean age 40.9, SD 12.3 y; n=150, 56% women) in Germany were analyzed. Physicians rated their chronic stress level and 11 relevant working conditions (ie, work stressors such as time pressure and work resources such as influence on sequence) both before and after either a fictional or real implementation of a relevant digital transformation at their workplace. In addition, a subsample of individuals (60; n=33, 55% women) submitted self-collected hair samples for cortisol analysis. RESULTS: The stress relevance of the selected working conditions was confirmed by significant correlations with self-rated chronic stress and hair cortisol levels (hair F) within the sample, all of them in the expected direction (P values between .01 and <.001). Multilevel modeling revealed significant differences associated with digital transformation in the rating of 8 (73%) out of 11 working conditions. More precisely, digital transformation was associated with potentially stress-enhancing effects in 6 working conditions (ie, influence on procedures and complexity of tasks) and stress-reducing effects in 2 other working conditions (ie, perceived workload and time pressure). Younger individuals, women, and individuals whose workplaces have implemented digital innovations tended to perceive digitalization-related differences in working conditions as rather stress-reducing. CONCLUSIONS: Our study lays the foundation for future hypothesis-based longitudinal research by identifying those working conditions that are stress relevant for physicians and prone to differ as a function of digital transformation and individual characteristics.

How does the modality of delivering force feedback influence the performance and learning of surgical suturing skills? We don't know, but we better find out! A review.

BACKGROUND: Force feedback is a critical element for performing and learning surgical suturing skill. Force feedback is impoverished or not present at all in non-open surgery (i.e., in simulation, laparoscopic, and robotic-assisted surgery), but it can be augmented using different modalities. This rapid, systematic review examines how the modality of delivering force feedback influences the performance and learning of surgical suturing skills. METHODS: An electronic search was performed on PubMed/MEDLINE, Web of Science, and Embase databases to identify relevant articles. The results were synthesized using vote counting based on direction of effect. RESULTS: A total of nine studies of medium-to-low quality were included. The synthesis of results suggests that the visual modality could be more beneficial than the tactile and auditory modalities in improving force control and that auditory and tactile modalities could be more beneficial than the visual modality in improving suturing performance. Results are mixed and unclear with regards to how modality affects the reduction of force magnitude and unclear when unimodal was compared to multimodal feedback. The studies have a general low level of evidence. CONCLUSION: The low number of studies with low methodological quality and low level of evidence (most were proof of concept) prevents us from drawing any meaningful conclusion and as such it is currently unknown whether and how force feedback modality influences surgical suturing skill. Speculatively, the visual modality may be more beneficial for improving the control of exerted force, while auditory and tactile modalities may be more effective in improving the overall suturing performance. We consider the issue of feedback modality to be highly relevant in this field, and we encourage future research to conduct further investigation integrating principles from learning psychology and neuroscience: identify feedback goal, context, and skill level and then design and compare feedback modalities accordingly.

Interleukin-8 is superior to CRP for the prediction of severe complications in a prospective cohort of patients undergoing major liver resection.

INTRODUCTION: Early detection of severe complications may reduce morbidity and mortality in patients undergoing hepatic resection. Therefore, we prospectively evaluated a panel of inflammatory blood markers for their value in predicting postoperative complications in patients undergoing liver surgery. METHODS: A total of 139 patients undergoing liver resections (45 wedge resections, 49 minor resections, and 45 major resections) were prospectively enrolled between August 2017 and December 2018. Leukocytes, CRP, neutrophil-lymphocyte ratio (NLR), thrombocyte-lymphocyte ratio (TLR), bilirubin, INR, and interleukin-6 and -8 (IL-6 and IL-8) were measured in blood drawn preoperatively and on postoperative days 1, 4, and 7. IL-6 and IL-8 were measured using standardized immunoassays approved for in vitro diagnostic use in Germany. ROC curve analysis was used to determine predictive values for the occurrence of severe postoperative complications (CDC ≥ 3). RESULTS: For wedge and minor resections, leukocyte counts at day 7 (AUC 0.80 and 0.82, respectively), IL-6 at day 7 (AUC 0.74 and 0.73, respectively), and CRP change (∆CRP) at day 7 (AUC 0.72 and 0.71, respectively) were significant predictors of severe postoperative complications. IL-8 failed in patients undergoing wedge resections, but was a significant predictor of severe complications after minor resections on day 7 (AUC 0.79), had the best predictive value in all patients on days 1, 4, and 7 (AUC 0.72, 0.72, and 0.80, respectively), and was the only marker with a significant predictive value in patients undergoing major liver resections (AUC on day 1: 0.70, day 4: 0.86, and day 7: 0.92). No other marker, especially not CRP, was predictive of severe complications after major liver surgery. CONCLUSION: IL-8 is superior to CRP in predicting severe complications in patients undergoing major hepatic resection and should be evaluated as a biomarker for patients undergoing major liver surgery. This is the first paper demonstrating a feasible implementation of IL-8 analysis in a clinical setting.

[Robot-assisted Minimally Invasive Oesophagectomy - Surgical Variants of Intrathoracic Circular Stapled Oesophagogastric Anastomosis]. / Roboterassistierte minimalinvasive Ösophagektomie ­ Varianten der intrathorakalen Ösophagogastrostomie mittels Zirkularstapler.

INTRODUCTION: Anastomotic insufficiency after oesophagectomy contributes significantly to morbidity and mortality of affected patients. A safe surgical technique can reduce the incidence of such anastomotic insufficiencies. INDICATION: In the treatment of oesophageal cancer, the German guideline recommends minimally invasive or hybrid surgical procedures. In most cases, Ivor-Lewis oesophagectomy and continuity reconstruction using a gastric sleeve are performed. Circular stapler anastomosis seems to be superior. METHOD: The preparation of the anastomosis starts intra-abdominally with mobilisation of the stomach and sparing of the gastroepiploic vessels. After the subsequent intrathoracic mobilisation of the oesophagus, the actual anastomosis construction can take place. Here, the oesophagus is either transected with a stapler closure or openly with scissors. This is followed by a purse-string suture on the open oesophageal stump. Alternatively, partial oesophageal opening with prior purse-string suture may later facilitate insertion of the stapler anvil. The anvil is placed in the oesophageal stump via minithoracotomy or alternatively transorally using a special gastric tube system. Subsequently, the anvil is fixated using the previously performed purse-string suture. Now the gastric sleeve can be pulled into the thorax. The oesophagus and small gastric curvature are placed extrathoracically through the minithoracotomy and a circular stapler is inserted into the gastric tube via an opening of the small curvature. The anastomosis then must be placed remotely from the gastroepiploic arcade. After construction of the anastomosis, the gastric sleeve is separated using a linear stapler. Eventually, the oesophagus and small gastric curvature can be completely recovered. Optionally, an additional suturing over the anastomosis and dissection margin of the gastric sleeve can be performed. CONCLUSION: In robot-assisted oesophagectomy, the reconstruction of continuity with a circular stapler anastomosis is quite possible and seems comparatively easier to learn. Nevertheless, variations are still possible within this procedure. However, there is no scientific evidence on the advantage for any method in a direct comparison.

Does caffeine consumption affect laparoscopic skills in a motion tracking analysis? A prospective, randomized, blinded crossover trial.

BACKGROUND: Coffee can increase vigilance and performance, especially during sleep deprivation. The hypothetical downside of caffeine in the surgical field is the potential interaction with the ergonomics of movement and the central nervous system. The objective of this trial was to investigate the influence of caffeine on laparoscopic performance. METHODS: Fifty laparoscopic novices participated in this prospective randomized, blinded crossover trial and were trained in a modified FLS curriculum until reaching a predefined proficiency. Subsequently, all participants performed four laparoscopic tasks twice, once after consumption of a placebo and once after a caffeinated (200 mg) beverage. Comparative analysis was performed between the cohorts. Primary endpoint analysis included task time, task errors, OSATS score and a performance analysis with an instrument motion analysis (IMA) system. RESULTS: Fifty participants completed the study. Sixty-eight percent of participants drank coffee daily. The time to completion for each task was comparable between the caffeine and placebo cohorts for PEG transfer (119 s vs 121 s; p = 0.73), precise cutting (157 s vs 163 s; p = 0.74), gallbladder resection (190 s vs 173 s; p = 0.6) and surgical knot (171 s vs 189 s; p = 0.68). The instrument motion analysis showed no significant differences between the caffeine and placebo groups in any parameters: instrument volume, path length, idle, velocity, acceleration, and instrument out of view. Additionally, OSATS scores did not differ between groups, regardless of task. Major errors occurred similarly in both groups, except for one error criteria during the circle cutting task, which occurred significantly more often in the caffeine group (34% vs. 16%, p < 0.05). CONCLUSION: The objective IMA and performance scores of laparoscopic skills revealed that caffeine consumption does not enhance or impair the overall laparoscopic performance of surgical novices. The occurrence of major errors is not conclusive but could be negatively influenced in part by caffeine intake.

Antibiotic resistance patterns of bacterial bile cultures during pancreatic surgery-a single center analysis and systematic review.

BACKGROUND: Septic complications after pancreatic surgery are common. However, it remains unclear if and how a shift of the microbiological spectrum affects morbidity. The aim of the present study was to assess the microbiological spectrum and antibiotic resistance patterns and their impact on outcome. METHODS: We conducted a retrospective study including patients undergoing pancreatic surgery at our center between 2005 and 2018. A systematic literature review and descriptive meta-analysis of the published and original data was performed according to the PRISMA guidelines. RESULTS: A total of 318 patients were included in the analysis. Patients with biliary drainage had a significantly higher incidence of bacterobilia (93% vs. 25%) and received preoperative antibiotics (46% vs. 12%). The analyzed bile cultures showed no resistance to piperacillin/tazobactam, fluoroquinolones, or carbapenems. Resistance to cefuroxime was seen in 58% of the samples of patients without biliary drainage (NBD) and 93% of the samples of those with drainage (BD). In general, there was no significant difference in overall postoperative morbidity. However, superficial surgical site infections (SSIs) were significantly more common in the BD group. We included a total of six studies and our own data (1627 patients) in the descriptive meta-analysis. The percentage of positive bile cultures ranged from 53 to 81%. In patients with BD, the most frequent microorganisms were Enterococcus spp. (58%), Klebsiella spp. (29%), and E. coli (27%). Almost all studies demonstrated resistance to first- and second-generation cephalosporins and to third- and fourth-generation cephalosporins for patients with BD. CONCLUSION: A change in perioperative antibiotic strategy according to local resistance patterns, especially after BD, might be useful for patients undergoing pancreatic surgery. Appropriate perioperative antibiotic coverage may help to prevent abdominal infectious complications and especially superficial SSIs.

Textbook outcome after pancreatoduodenectomy and distal pancreatectomy with postoperative hyperamylasemia-a propensity score matching analysis.

PURPOSE: Postoperative serum hyperamylasemia (POH) is a part of the new, increasingly highlighted, definition for postpancreatectomy pancreatitis (PPAP). This study aimed to analyze whether the biochemical changes of PPAP are differently associated with postoperative complications after distal pancreatectomy (DP) compared with pancreatoduodenectomy (PD). The textbook outcome (TO) was used as a summary measure to capture real-world data. METHODS: The data were retrospectively extracted from a prospective clinical database. Patients with POH, defined as levels above our institution's upper limit of normal on postoperative day 1, after DP and the corresponding propensity score-matched cohort after PD were evaluated on postoperative complications by using logistic regression analyses. RESULTS: We analyzed 723 patients who underwent PD and DP over a period of 9 years. After propensity score matching, 384 patients (192 patients in each group) remained. POH was observed in 78 (41.1%) and 74 (39.4%) after PD and DP correspondingly. There was a significant increase of postoperative complications in the PD group: Clavien-Dindo classification system ≥3 (P < .01 vs P = .71), clinically relevant postoperative pancreatic fistula (P < .001 vs P = .2), postpancreatectomy hemorrhage (P < .001 vs P = .11), and length of hospital stay (P < .001 vs P = .69) if POH occurred compared with in the DP group. TO was significantly unlikely in cases with POH after PD compared with DP (P > .001 vs P = .41). Furthermore, POH was found to be an independent predictor for missing TO after PD (odds ratio [OR], 0.29; 95% CI, 0.14-0.60; P < .001), whereas this was not observed in patients after DP (OR, 0.53; 95% CI, 0.21-1.33; P = .18). CONCLUSION: As a part of the definition for PPAP, POH is a predictive indicator associated with postoperative complications after PD but not after DP.

Does practice make perfect? Laparoscopic training mainly improves motion efficiency: a prospective trial.

Training improves skills in minimally invasive surgery. This study aimed to investigate the learning curves of complex motion parameters for both hands during a standardized training course using a novel measurement tool. An additional focus was placed on the parameters representing surgical safety and precision. Fifty-six laparoscopic novices participated in a training course on the basic skills of minimally invasive surgery based on a modified Fundamentals of Laparoscopic Surgery (FLS) curriculum. Before, twice during, and once after the practical lessons, all participants had to perform four laparoscopic tasks (peg transfer, precision cut, balloon resection, and laparoscopic suture and knot), which were recorded and analyzed using an instrument motion analysis system. Participants significantly improved the time per task for all four tasks (all p < 0.001). The individual instrument path length decreased significantly for the dominant and non-dominant hands in all four tasks. Similarly, both hands became significantly faster in all tasks, with the exception of the non-dominant hand in the precision cut task. In terms of relative idle time, only in the peg transfer task did both hands improve significantly, while in the precision cut task, only the dominant hand performed better. In contrast, the motion volume of both hands combined was reduced in only one task (precision cut, p = 0.01), whereas no significant improvement in the relative time of instruments being out of view was observed. FLS-based skills training increases motion efficiency primarily by increasing speed and reducing idle time and path length. Parameters relevant for surgical safety and precision (motion volume and relative time of instruments being out of view) are minimally affected by short-term training. Consequently, surgical training should also focus on safety and precision-related parameters, and assessment of these parameters should be incorporated into basic skill training accordingly.

Tumour catabolism independent of malnutrition and inflammation in upper GI cancer patients revealed by longitudinal metabolomics.

BACKGROUND: The detrimental impact of malnutrition and cachexia in cancer patients subjected to surgical resection is well established. However, how systemic and local metabolic alterations in cancer patients impact the serum metabolite signature, thereby leading to cancer-specific differences, is poorly defined. In order to implement metabolomics as a potential tool in clinical diagnostics and disease follow-up, targeted metabolite profiling based on quantitative measurements is essential. We hypothesized that the quantitative metabolic profile assessed by 1 H nuclear magnetic resonance (NMR) spectroscopy can be used to identify cancer-induced catabolism and potentially distinguish between specific tumour entities. Importantly, to prove tumour dependency and assess metabolic normalization, we additionally analysed the metabolome of patients' sera longitudinally post-surgery in order to assess metabolic normalization. METHODS: Forty two metabolites in sera of patients with tumour entities known to cause malnutrition and cachexia, namely, upper gastrointestinal cancer and pancreatic cancer, as well as sera of healthy controls, were quantified by 1 H NMR spectroscopy. RESULTS: Comparing serum metabolites of patients with gastrointestinal cancer with healthy controls and pancreatic cancer patients, we identified at least 15 significantly changed metabolites in each comparison. Principal component and pathway analysis tools showed a catabolic signature in preoperative upper gastrointestinal cancer patients. The most specifically upregulated metabolite group in gastrointestinal cancer patients was ketone bodies (3-hydroxybutyrate, P < 0.0001; acetoacetate, P < 0.0001; acetone, P < 0.0001; false discovery rate [FDR] adjusted). Increased glycerol levels (P < 0.0001), increased concentration of the ketogenic amino acid lysine (P = 0.03) and a significant correlation of 3-hydroxybutyrate levels with branched-chained amino acids (leucine, P = 0.02; isoleucine, P = 0.04 [FDR adjusted]) suggested that ketone body synthesis was driven by lipolysis and amino acid breakdown. Interestingly, the catabolic signature was independent of the body mass index, clinically assessed malnutrition using the nutritional risk screening score, and systemic inflammation assessed by CRP and leukocyte count. Longitudinal measurements and principal component analyses revealed a quick normalization of key metabolic alterations seven days post-surgery, including ketosis. CONCLUSIONS: Together, the quantitative metabolic profile obtained by 1 H NMR spectroscopy identified a tumour-induced catabolic signature specific to upper gastrointestinal cancer patients and enabled monitoring restoration of metabolic homeostasis after surgery. This approach was critical to identify the obtained metabolic profile as an upper gastrointestinal cancer-specific signature independent of malnutrition and inflammation.

Associations Between Binocular Depth Perception and Performance Gains in Laparoscopic Skill Acquisition.

The ability to perceive differences in depth is important in many daily life situations. It is also of relevance in laparoscopic surgical procedures that require the extrapolation of three-dimensional visual information from two-dimensional planar images. Besides visual-motor coordination, laparoscopic skills and binocular depth perception are demanding visual tasks for which learning is important. This study explored potential relations between binocular depth perception and individual variations in performance gains during laparoscopic skill acquisition in medical students naïve of such procedures. Individual differences in perceptual learning of binocular depth discrimination when performing a random dot stereogram (RDS) task were measured as variations in the slope changes of the logistic disparity psychometric curves from the first to the last blocks of the experiment. The results showed that not only did the individuals differ in their depth discrimination; the extent with which this performance changed across blocks also differed substantially between individuals. Of note, individual differences in perceptual learning of depth discrimination are associated with performance gains from laparoscopic skill training, both with respect to movement speed and an efficiency score that considered both speed and precision. These results indicate that learning-related benefits for enhancing demanding visual processes are, in part, shared between these two tasks. Future studies that include a broader selection of task-varying monocular and binocular cues as well as visual-motor coordination are needed to further investigate potential mechanistic relations between depth perceptual learning and laparoscopic skill acquisition. A deeper understanding of these mechanisms would be important for applied research that aims at designing behavioral interventions for enhancing technology-assisted laparoscopic skills.

Investigating the utility of VR for spatial understanding in surgical planning: evaluation of head-mounted to desktop display.

Recent technological advances have made Virtual Reality (VR) attractive in both research and real world applications such as training, rehabilitation, and gaming. Although these other fields benefited from VR technology, it remains unclear whether VR contributes to better spatial understanding and training in the context of surgical planning. In this study, we evaluated the use of VR by comparing the recall of spatial information in two learning conditions: a head-mounted display (HMD) and a desktop screen (DT). Specifically, we explored (a) a scene understanding and then (b) a direction estimation task using two 3D models (i.e., a liver and a pyramid). In the scene understanding task, participants had to navigate the rendered the 3D models by means of rotation, zoom and transparency in order to substantially identify the spatial relationships among its internal objects. In the subsequent direction estimation task, participants had to point at a previously identified target object, i.e., internal sphere, on a materialized 3D-printed version of the model using a tracked pointing tool. Results showed that the learning condition (HMD or DT) did not influence participants' memory and confidence ratings of the models. In contrast, the model type, that is, whether the model to be recalled was a liver or a pyramid significantly affected participants' memory about the internal structure of the model. Furthermore, localizing the internal position of the target sphere was also unaffected by participants' previous experience of the model via HMD or DT. Overall, results provide novel insights on the use of VR in a surgical planning scenario and have paramount implications in medical learning by shedding light on the mental model we make to recall spatial structures.

The Hunger Games: Laparoscopic Performance in Novice Surgeons is Not Altered by Food Deprivation but Influenced by the Degree of Appetite - A Randomized Controlled Trial.

OBJECTIVES: Food deprivation is a common condition for visceral surgeons and especially laparoscopic approaches require high levels of concentration. The current literature does not provide adequate answers whether intraoperative breaks, especially food intake, might influence the quality of the surgical skills. Thus, the primary aim of this trial was to analyze the influence of food deprivation on the laparoscopic performance. DESIGN SETTING AND PARTICIPANTS: 37 laparoscopic novices participated from 10/2017 to 04/2018 in this single center, prospective-randomized trial and were trained during laparoscopic training sessions until they reached a predefined level of proficiency. Subsequently, participants were randomized into 3 different groups: food deprivation of 8 hours, 4 hours, or carbohydrate loading directly prior to the laparoscopic exam. The exam comprised PEG-transfer, precise cutting, gallbladder resection and surgical knot. MAIN FINDINGS: Completion time for PEG-transfer, precise cutting, gallbladder resection and surgical knot was 63s, 139s, 192s and 272s respectively. Participants starving for 8 hours performed 3 of 4 tasks more slowly whilst participants starving for 4 hours performed 3 of 4 tasks faster than the average. Analyzing self-reported level of appetite revealed: Students with an intermediate level were significantly faster (p <0.05) during complex procedures compared to participants that reported hunger prior to performing these tasks (192s vs. 307s). Additionally, hungry students had been more inaccurate during the surgical knot (p <0.05) whilst students with intermediate appetite level tend to be most accurate (p - value 0.012). CONCLUSIONS: The subjective level of appetite rather than the absolute number of fasting hours influences the laparoscopic performance most. Thus, any extreme level of appetite may be avoided and surgeons may achieve the best performance when they have an intermediate level of appetite. In consequence, heavy meals may be omitted immediately prior to demanding laparoscopic procedures and surgeons may have access to mini-breaks and refreshers during major procedures.

Development of a new serological assay for the diagnosis of Clostridium difficile infections with prognostic value.

PURPOSE: The most common hospital-acquired enteral infection is caused by Clostridium difficile. Unfortunately, Clostridium difficile infections (CDI) are of high risk to recur and little is known about how to predict recurrences. Previous findings have shown that high risk for recurrence correlates with low levels of C. difficile toxin-A and -B specific antibodies suggesting the protective role of humoral immunity against bacterial virulence factors. Therefore, the aim of this study was to develop an immunoassay, which specifically measures C.difficile toxin-specific antibodies in the serum that might be correlated with the risk of recurrence. METHODS: We developed a simple ELISA to measure the quantity of toxin-A and -B-specific antibodies in human serum. The assay was then used to test anti-toxin immune response in healthy controls, in patients with primary CDI and patients with CDI recurrence. RESULTS: The developed assay is simple, reproducible and fast. When using this test in a small clinical trial our results showed a trend toward a higher antibody level in those patients with only one episode of CDI, whereas patients with recurrent CDI had less anti-toxin A or B-specific antibodies in their serum indicating inadequate C. difficile anti-toxin immunity may facilitate recurrent infections. CONCLUSIONS: It has already been observed that low antibody levels are associated with recurrent CDI (Bauer et al., 2014). The findings of our clinical trial show a similar trend. Our developed ELISA test could help to conduct further research and it might be helpful in clinical use to detect patients of high risk for CDI recurrence.