Intraoperative pelvic neuromonitoring based on bioimpedance signals: a new method analyzed on 30 patients.

PURPOSE: Increasing importance has been attributed in recent years to the preservation of the pelvic autonomic nerves during rectal resection to achieve better functional results. In addition to improved surgical techniques, intraoperative neuromonitoring may be useful. METHODS: This single-arm prospective study included 30 patients who underwent rectal resection performed with intraoperative neuromonitoring by recording the change in the tissue impedance of the urinary bladder and rectum after stimulation of the pelvic autonomic nerves. The International Prostate Symptom Score, the post-void residual urine volume and the Low Anterior Resection Syndrome Score (LARS score) were assessed during the 12-month follow-up period. RESULTS: A stimulation-induced change in tissue impedance was observed in 28/30 patients (93.3%). In the presence of risk factors such as low anastomosis, neoadjuvant radiotherapy and a deviation stoma, an average increase of the LARS score by 9 points was observed 12 months after surgery (p = 0,04). The function of the urinary bladder remained unaffected in the first week (p = 0,7) as well as 12 months after the procedure (p = 0,93). CONCLUSION: The clinical feasibility of the new method for pelvic intraoperative neuromonitoring could be verified. The benefits of intraoperative pelvic neuromonitoring were particularly evident in difficult intraoperative situations with challenging visualization of the pelvic nerves.

Virtual patients in the acquisition of clinical reasoning skills: does presentation mode matter? A quasi-randomized controlled trial.

BACKGROUND: The objective of this study is to compare two different instructional methods in the curricular use of computerized virtual patients in undergraduate medical education. We aim to investigate whether using many short and focused cases - the key feature principle - is more effective for the learning of clinical reasoning skills than using few long and systematic cases. METHODS: We conducted a quasi-randomized, non-blinded, controlled parallel-group intervention trial in a large medical school in Southwestern Germany. During two seminar sessions, fourth- and fifth-year medical students (n = 56) worked on the differential diagnosis of the acute abdomen. The educational tool - virtual patients - was the same, but the instructional method differed: In one trial arm, students worked on multiple short cases, with the instruction being focused only on important elements ("key feature arm", n = 30). In the other trial arm, students worked on few long cases, with the instruction being comprehensive and systematic ("systematic arm", n = 26). The overall training time was the same in both arms. The students' clinical reasoning capacity was measured by a specifically developed instrument, a script concordance test. Their motivation and the perceived effectiveness of the instruction were assessed using a structured evaluation questionnaire. RESULTS: Upon completion of the script concordance test with a reference score of 80 points and a standard deviation of 5 for experts, students in the key feature arm attained a mean of 57.4 points (95% confidence interval: 50.9-63.9), and in the systematic arm, 62.7 points (57.2-68.2), with Cohen's d at 0.337. The difference is statistically non-significant (p = 0.214). In the evaluation survey, students in the key feature arm indicated that they experienced more time pressure and perceived the material as more difficult. CONCLUSIONS: In this study powered for a medium effect, we could not provide empirical evidence for the hypothesis that a key feature-based instruction on multiple short cases is superior to a systematic instruction on few long cases in the curricular implementation of virtual patients. The results of the evaluation survey suggest that learners should be given enough time to work through case examples, and that caution should be taken to prevent cognitive overload.

Validation of undergraduate medical student script concordance test (SCT) scores on the clinical assessment of the acute abdomen.

BACKGROUND: Health professionals often manage medical problems in critical situations under time pressure and on the basis of vague information. In recent years, dual process theory has provided a framework of cognitive processes to assist students in developing clinical reasoning skills critical especially in surgery due to the high workload and the elevated stress levels. However, clinical reasoning skills can be observed only indirectly and the corresponding constructs are difficult to measure in order to assess student performance. The script concordance test has been established in this field. A number of studies suggest that the test delivers a valid assessment of clinical reasoning. However, different scoring methods have been suggested. They reflect different interpretations of the underlying construct. In this work we want to shed light on the theoretical framework of script theory and give an idea of script concordance testing. We constructed a script concordance test in the clinical context of "acute abdomen" and compared previously proposed scores with regard to their validity. METHODS: A test comprising 52 items in 18 clinical scenarios was developed, revised along the guidelines and administered to 56 4(th) and 5(th) year medical students at the end of a blended-learning seminar. We scored the answers using five different scoring methods (distance (2×), aggregate (2×), single best answer) and compared the scoring keys, the resulting final scores and Cronbach's α after normalization of the raw scores. RESULTS: All scores except the single best answers calculation achieved acceptable reliability scores (>= 0.75), as measured by Cronbach's α. Students were clearly distinguishable from the experts, whose results were set to a mean of 80 and SD of 5 by the normalization process. With the two aggregate scoring methods, the students' means values were between 62.5 (AGGPEN) and 63.9 (AGG) equivalent to about three expert SD below the experts' mean value (Cronbach's α : 0.76 (AGGPEN) and 0.75 (AGG)). With the two distance scoring methods the students' mean was between 62.8 (DMODE) and 66.8 (DMEAN) equivalent to about two expert SD below the experts' mean value (Cronbach's α: 0.77 (DMODE) and 0.79 (DMEAN)). In this study the single best answer (SBA) scoring key yielded the worst psychometric results (Cronbach's α: 0.68). CONCLUSION: Assuming the psychometric properties of the script concordance test scores are valid, then clinical reasoning skills can be measured reliably with different scoring keys in the SCT presented here. Psychometrically, the distance methods seem to be superior, wherein inherent statistical properties of the scales might play a significant role. For methodological reasons, the aggregate methods can also be used. Despite the limitations and complexity of the underlying scoring process and the calculation of reliability, we advocate for SCT because it allows a new perspective on the measurement and teaching of cognitive skills.

Long-term results after endoanal advancement flap repair for fistulas-in-ano. How important is the aetiology?

PURPOSE: The purpose of this study was to assess primary healing, recurrence and continence after endoanal advancement flap repair (EAFR). PATIENTS AND METHODS: Seventy-seven patients with fistulas-in-ano of different etiologies received endoanal advancement flap repair between 1997 and 2009. This is a prospective, non-randomized, single-centre, single-surgeon study. RESULTS: Follow-up data was available for 71 patients. 47.9 % had cryptoglandular fistulas. In 40.8 %, the fistulas were due to chronic inflammatory bowel disease. In 11.3 %, the fistula was a consequence of treatment for cancer. Primary healing was observed in 41 of the cases (57.7 %). The median time to recurrence was 27 months (mean 43.43 ± 48.11) and differed significantly across the patient groups: cryptoglandular origin 51 months (mean 57.09 ± 52.57), condition after cancer treatment 43 months (mean 31 ± 23.142), inflammatory bowel disease 11 months (mean 23.65 ± 32.47) (p < 0.01). Preoperatively, 31 (44.3 %) of the patients had impaired continence vs 30 (42.9 %) postoperatively. Overall, postoperative mean Cleveland Clinic incontinence score values improved significantly (preoperative 3.74 ± 4.558 vs postoperative 2.68 ± 4.752, p = 0.03). CONCLUSIONS: Full-thickness endoanal advancement flap repair is a successful treatment option for a range of fistula etiologies. Overall, fistula aetiology proved to be prognostically more relevant than fistula location. Fistulas associated with chronic inflammatory bowel disease were found to have a significantly higher rate of recurrence and shorter time to recurrence at long-term follow-up. Repeat interventions do not negatively impact postoperative continence.

Reduction of Acute Shoulder Dislocations in a Remote Environment: A Prospective Multicenter Observational Study.

OBJECTIVE: Acute dislocations of the glenohumeral joint are common in wilderness activities. Emergent reduction should take place at the site of trauma to reduce the patient's pain and the risk of vascular and neurological complications. A limited number of reduction methods are applicable in remote areas. The aim of this study is to present our method of reduction of anterior shoulder luxation that is easily applicable in remote areas without medication, adjuncts, and assistants and is well tolerated by patients. METHODS: A prospective observational study was conducted during a 5-year period. The patients included underwent closed manual reduction with our technique. After each reduction, the physician who performed the reduction completed a standardized detailed history, and reexamined the patient (for acute complications). The patients were contacted 6 months after the trauma to investigate long-term postreduction complications. RESULTS: Reduction was achieved with our method in 39 (100.0%) of 39 patients. The mean pain felt during our reduction procedure was rated 1.7 ± 1.4 (on a scale of 10) using the visual analog scale scoring system. No complications were noted before or after the reduction attempts. We did not find any long-term complications. CONCLUSIONS: The reduction method presented in the present study is an effective method for the reduction of acute shoulder luxations in remote places. Our data suggest that this method could be applied for safe and effective reduction of shoulder dislocation.

Impact of neoadjuvant chemotherapy with PELF-protocoll versus surgery alone in the treatment of advanced gastric carcinoma.

BACKGROUND: In a retrospective study we analyzed the impact of neoadjuvant chemotherapy (CTx) with the PELF - protocol (Cisplatin, Epirubicin, Leukovorin, 5-Fluoruracil) on mortality, recurrence and prognosis of patients with advanced gastric carcinoma, UICC stages Ib-III. METHODS: 64 patients were included. 26 patients received neoadjuvant CTx followed by surgical resection, 38 received surgical resection only. Tumor staging was performed by endoscopy, endosonography, computed tomography and laparoscopy. Patients staged Ib - III received two cycles of CTx according to the PELF-protocol. Adjuvant chemotherapy was not performed at all. RESULTS: Complete (CR) or partial response (PR) was seen in 20 patients (77%), 19% showing CR and 58% PR. No benefit was observed in 6 patients (23%). Two of these 6 patients displayed tumor progression during CTx. Major toxicity was defined as grade 3 to 4 neutropenia or gastrointestinal side effects. One patient died under CTx because of neutropenia and was excluded from the overall patient collective. The curative resection rate was 77% after CTx and 74% after surgery only. The perioperative morbidity rate after CTx was 39% versus 66% after resection only. Recurrence rate after CTx was 38% and 61% after surgery alone; we detected an effective reduction of locoregional recurrence (12% vs. 26%). The overall survival was 38% after CTx and 42% after resection only. The 5-year survival rates were 45% in responders, 20% in non - responders and 42% in only resected patients. A subgroup analysis indicates that responders with stage III tumors may benefit with respect to their 5-year survival in comparable patients without neoadjuvant CTx. As to be expected, non-responders with stage III tumors did not benefit with respect to their survival. The 5-year-survival was approximated using a Kaplan-Meier curve and compared using a log-rank test. CONCLUSION: In patients with advanced gastric carcinoma, neoadjuvant CTx with the PELF- protocol significantly reduces the recurrence rate, especially locoregionally, compared to surgery alone. In our study, there was no overall survival benefit after a 5-year follow-up period. Alone a subgroup of patients with stage III tumors appear to benefit significantly in the long term from neoadjuvant CTx.

Automatic muscle impedance and nerve analyzer (AMINA) as a novel approach for classifying bioimpedance signals in intraoperative pelvic neuromonitoring.

Frequent complications arising from low anterior resections include urinary and fecal incontinence, as well as sexual disorders, which are commonly associated with damage to the pelvic autonomic nerves during surgery. To assist the surgeon in preserving pelvic autonomic nerves, a novel approach for intraoperative pelvic neuromonitoring was investigated that is based on impedance measurements of the innervated organs. The objective of this work was to develop an algorithm called AMINA to classify the bioimpedance signals, with the goal of facilitating signal interpretation for the surgeon. Thirty patients included in a clinical investigation underwent nerve-preserving robotic rectal surgery using intraoperative pelvic neuromonitoring. Contraction of the urinary bladder and/or rectum, triggered by direct stimulation of the innervating nerves, resulted in a change in tissue impedance signal, allowing the nerves to be identified and preserved. Impedance signal characteristics in the time domain and the time-frequency domain were calculated and classified to develop the AMINA. Stimulation-induced positive impedance changes were statistically significantly different from negative stimulation responses by the percent amplitude of impedance change Amax in the time domain. Positive impedance changes and artifacts were distinguished by classifying wavelet scales resulting from peak detection in the continuous wavelet transform scalogram, which allowed implementation of a decision tree underlying the AMINA. The sensitivity of the software-based signal evaluation by the AMINA was 96.3%, whereas its specificity was 91.2%. This approach streamlines and automates the interpretation of impedance signals during intraoperative pelvic neuromonitoring.

Experience with a new prosthetic anal sphincter in three coloproctological centres.

BACKGROUND: Fecal incontinence is a common and severely disabling disorder. For patients with severe fecal incontinence, surgery may prove to be the only adequate treatment option. METHODS: This study reports on 43 patients that were treated with a prosthetic sphincter system between 2005 and 2009 in three coloproctological centres. MAIN OUTCOME MEASURES: complications, anal pressures before and after surgery, fecal continence score. RESULTS: The new artificial sphincter system significantly improves continence but leads to some complications in clinical practice. After implantation of the device, continence improved significantly (Keller & Jostarndt continence score 2.6 to 14.3 (P < 0.01)). With the band activated, resting pressure improved significantly as compared to baseline (10.7 mmHg vs. 66.1 mm Hg, P < 0.01). The same holds for anal sphincter squeeze pressure (32.2 mmHg versus 85.9 mm Hg, P < 0.01). Complications occurred in 21 patients (48.8%): 10 surgical and 13 technical. Two patients were affected by both technical and surgical problems. The median time of the occurrence was 3 months postop. In five patients difficulties arose within the first postoperative month leading to explantation of the device in three patients. 90% of complications occurred in the first year. CONCLUSIONS: The soft anal band of AMI (AAS), a new artificial anal sphincter, improves severe anal incontinence, but it must be regarded as a last treatment option to avoid a stoma.

Technical aspects of a new approach to intraoperative pelvic neuromonitoring during robotic rectal surgery.

It has been found that rectal surgery still leads to high rates of postoperative urinary, fecal, or sexual dysfunction, which is why nerve-sparing surgery has gained increasing importance. To improve functional outcomes, techniques to preserve pelvic autonomic nerves by identifying anatomic landmarks and implementing intraoperative neuromonitoring methods have been investigated. The objective of this study was to transfer a new approach to intraoperative pelvic neuromonitoring based on bioimpedance measurement to a clinical setting. Thirty patients (16 male, 14 female) involved in a prospective clinical investigation (German Clinical Trials Register DRKS00017437, date of first registration 31/03/2020) underwent nerve-sparing rectal surgery using a new approach to intraoperative pelvic neuromonitoring based on direct nerve stimulation and impedance measurement on target organs. Clinical feasibility of the method was outlined in 93.3% of the cases. Smooth muscle contraction of the urinary bladder and/ or the rectum in response to direct stimulation of innervating functional nerves correlated with a change in tissue impedance compared with the pre-contraction state. The mean amplitude (Amax) of positive signal responses was Amax = 3.8%, negative signal responses from a control tissue portion with no stimulation-induced impedance change had an amplitude variation of 0.4% on average. The amplitudes of positive and negative signal responses differed significantly (statistical analysis using two-sided t-test), allowing the nerves to be identified and preserved. The results indicate a reliable identification of pelvic autonomic nerves during rectal surgery.

A new method of intraoperative pelvic neuromonitoring: a preclinical feasibility study in a porcine model.

Low anterior resections (LAR) are frequently associated with complications such as urinary and fecal incontinence as well as sexual disorders. Typical risk factors are rectal cancer with low tumor location, preoperative radiotherapy, and surgery-related damage of pelvic autonomic nerves. As preserving the pelvic autonomic nerves without any technical assistance is challenging, the objective of this preclinical study was to investigate the technical feasibility of a new method for intraoperative pelvic neuromonitoring. Twelve female pigs undergoing low anterior resections were involved in a prospective preclinical study. Intraoperative pelvic neuromonitoring included direct pelvic nerve stimulation and tissue impedance measurement on the urinary bladder and the rectum for the identification of efferent pelvic nerves in the surgical area. Immunohistochemistry was used to verify the results. Smooth muscle contraction of the urinary bladder and/or the rectum in response to direct stimulation of the innervating nerves was detectable with impedance measurement. The macroscopic contraction of both the urinary bladder and the rectum correlated with a change in tissue impedance compared to the status before contraction. Thus, it was possible to identify pelvic nerves in the surgical area, which allows the nerves to be preserved. The results indicate a reliable identification of pelvic autonomic nerves, which allows nerve damage to be prevented in the future.

To band or not to band--early results of banded sleeve gastrectomy.

Laparoscopic sleeve gastrectomy (LSG) is the procedure with the fastest growing numbers worldwide. Although excellent weight loss can be achieved, one major obstacle of LSG is weight regain due to sleeve dilatation. Banded sleeve gastrectomy (BLSG) has been described as an option to counteract sleeve dilatation and ameliorate weight loss over time. In a retrospective study, we analysed 25 patients who underwent BLSG using a MiniMizer® ring. Twenty five patients who had previously undergone a conventional LSG were selected for matched-pair analysis. Patient follow-up was 12 months in both groups. Mean preoperative BMI was 56.1 ± 7.2 kg/m(2) for BLSG and 57.0 ± 6.3 kg/m(2) for LSG, P = 0.522. Operative time was significantly shorter for BLSG (53 ± 27 min vs. 68 ± 20 min, P = 0.0025). Excess weight loss (%EWL) was equal in both groups with %EWL at 12 months of 58.0 ± 14.6 % for BSLG patients vs. 58.4 ± 19.2 % for LSG patients. There was no procedure-related mortality in either group. At 12 months postoperative, vomiting was significantly increased in BSLG patients (OR 6.75, P = 0.035). New onset reflux was equal in both groups (OR 0.67, P = 0.469). Ring implantation does not increase the duration of surgery or early surgical complications. Weight loss in the first follow-up year is not influenced, but the incidence of vomiting is raised after 12 months when patients start to increase eating volume.

Systematic ileal transposition in Zucker rats shows advantage for long segment distal transposition.

INTRODUCTION: The possibility of achieving diabetes remission through bariatric surgery has dramatically changed treatment options for this disease. Ileal transposition (IT), specifically designed to provoke diabetes remission, has so far shown great success in rodent studies. However, it remains uncertain which combination of ileal length and origin produces best results. METHODS: Forty male Zucker rats underwent transposition of 25% distal, 50% distal, and 50% proximal ileum or sham surgery. Glucose control, insulin, and glucagon-like peptide (GLP)-1 serum levels were analyzed after 1, 3, and 6 months. Body weight was recorded weekly. RESULTS: In relation to sham-operated animals, the 50% distal IT presented with improved glucose tolerance after 1, 3, and 6 months (2-way analysis of variance [ANOVA]: P < .05, < .0001, and < .0001, respectively). The 25% distal and 50% proximal IT only showed improved glucose control after 3 months, suggesting a fading effect in long-term observation (2-way ANOVA: P < .0001 for both). Glucose-stimulated GLP-1 levels were steadily elevated only in the 2 distal IT groups (Mann-Whitney sham versus 50% distal, P < .01, < .01, and < .05; sham versus 25% distal, P < .01, = .001, < .05 for 1, 3, and 6 months, respectively). IT had no impact on serum insulin levels. CONCLUSION: The current study restates the findings of improved glucose tolerance and GLP-1 stimulation after IT, but is the first to demonstrate a fading glycemic effect in long-term observation. Systematic comparison of length and ileal origin revealed that long and distal transposition delivers best results.

Long segment ileal transposition leads to early amelioration of glucose control in the diabetic obese Zucker rat.

INTRODUCTION: Fast delivery of food to the terminal ileum is thought to be pathophysiologically responsible for type 2 diabetes remission after obesity surgery. Imitating this effect, ileal transposition (IT) is designed as initiating diabetes remission for non-obese patients. AIM: To date, it is not clear which length of the transposed segment achieves the best glucose lowering results. As previous rodent data mostly rely on a 10 cm IT, the current study evaluated a long segment IT (20 cm) in the diabetic obese Zucker rat. MATERIAL AND METHODS: Twenty male diabetic obese Zucker rats (Crl:ZUC-Lepr(fa)) were randomly assigned to undergo either a long segment (20 cm; ∼ 50% of ileum) IT or sham surgery. Glucose control was determined by an oral glucose tolerance test (OGTT) on day -7, 0, 14 and 20. Analysis of the incretin hormones glucagon-like peptide 1 (GLP-1), peptide YY (PYY) and insulin was included in the first and third OGTT. RESULTS: Ileal transposition animals showed an early improvement of glucose control after 14 days (area under the curve: IT vs. baseline 314.7 ±229.0 mmol/l × min vs. 564.6 ±268.5 mmol/l × min; p < 0.05). Compared to sham animals, glucose-stimulated GLP-1 and PYY levels were raised (5.75 ±3.73 pmol/l vs. 18.52 ±14.22 pmol/l, p < 0.05; 129.7 ±64.62 pmol/l vs. 164.0 ±62.26 pmol/l, p < 0.05). Body weight gain from postoperative day 5 was greater for sham animals (50.22 ±20.93 γ vs. 16.4 ±25.93 g; p < 0.01). CONCLUSIONS: Long segment IT shows a rapid rise in GLP-1 and PYY levels, thus leading to early amelioration of glucose control.