Machine learning to predict myocardial injury and death after non-cardiac surgery.

Myocardial injury due to ischaemia within 30 days of non-cardiac surgery is prognostically relevant. We aimed to determine the discrimination, calibration, accuracy, sensitivity and specificity of single-layer and multiple-layer neural networks for myocardial injury and death within 30 postoperative days. We analysed data from 24,589 participants in the Vascular Events in Non-cardiac Surgery Patients Cohort Evaluation study. Validation was performed on a randomly selected subset of the study population. Discrimination for myocardial injury by single-layer vs. multiple-layer models generated areas (95%CI) under the receiver operating characteristic curve of: 0.70 (0.69-0.72) vs. 0.71 (0.70-0.73) with variables available before surgical referral, p < 0.001; 0.73 (0.72-0.75) vs. 0.75 (0.74-0.76) with additional variables available on admission, but before surgery, p < 0.001; and 0.76 (0.75-0.77) vs. 0.77 (0.76-0.78) with the addition of subsequent variables, p < 0.001. Discrimination for death by single-layer vs. multiple-layer models generated areas (95%CI) under the receiver operating characteristic curve of: 0.71 (0.66-0.76) vs. 0.74 (0.71-0.77) with variables available before surgical referral, p = 0.04; 0.78 (0.73-0.82) vs. 0.83 (0.79-0.86) with additional variables available on admission but before surgery, p = 0.01; and 0.87 (0.83-0.89) vs. 0.87 (0.85-0.90) with the addition of subsequent variables, p = 0.52. The accuracy of the multiple-layer model for myocardial injury and death with all variables was 70% and 89%, respectively.

Comparison of conservative versus surgical therapy for acute appendicitis with abscess in five German hospitals.

INTRODUCTION: The aim of this study was to evaluate the effectiveness of initially conservative therapy compared to immediate appendectomy for acute appendicitis with abscess in terms of medical and economic outcomes. METHODS: Of all the patients treated for appendicitis from January 2009 to December 2017 in five German hospitals, 240 were included in the study. Fifty-three patients received conservative (CON) and 195 patients received surgical (SUR) therapy as initial treatment. RESULTS: Length of stay was similar (12.5 days in CON vs. 13.3 days in SUR, p = 0.530). Readmission rate was higher in the conservative group (54.7% vs. 6.2%, p < 0.001). The majority (53.7%) of the 41 operations in CON group were appendectomies (22 procedures), 1 (4.5%) of them was in the first hospital stay because of persisting symptoms, 21 (95.5%) after a recovery interval. Seven (33.3%) of the recovery appendectomies were performed due to persisting or recurrent symptoms and 14 (66.7%) due to the request of patient. Twenty-one patients (39.6%) in the CON group did not need surgery. The rates of complication-related operations per patient (0.04 versus 0.58, p < 0.001), conversions of surgical technique (1.9% vs. 34.9%, p = 0.0287), and extended resections (1.9% vs. 31.3%, p < 0.001) were higher in SUR group. Furthermore, morbidity, hospital costs, and loss in quality of life were significantly higher in the surgical group (17.0% vs. 66.2%, p < 0.001; € 5044 vs. € 8457, p < 0.001, and 4.3 days vs. 7.5 days, p < 0.001, CON vs. SUR). CONCLUSION: Initially, conservative treatment for acute appendicitis with abscess is preferable to immediate surgical treatment in reduction of morbidity, hospital costs, and loss in quality of life.

Two-dimensional plasmonic grating for increased quantum efficiency in midwave infrared nBn detectors with thin absorbers.

We demonstrate a strategy for increasing the operating temperatures of nBn midwave infrared (MWIR) focal plane arrays, based on the use of two-dimensional plasmonic gratings to enhance the quantum efficiency (QE) of structures with very thin absorbers. Reducing the absorber volume correspondingly reduces the dark current in a diffusion-limited photodiode, while light trapping mediated by the plasmonic grating increases the net absorbance to maintain high QE. The plasmonically enhanced nBn MWIR sensors with absorber thicknesses of only 0.5 µm exhibit peak internal QEs as high as 57%, which enables a 5-fold reduction in dark current. Numerical simulations indicate the potential for further improvement.

Laparoscopic resection of right colon cancer-a matched pairs analysis.

PURPOSE: Laparoscopy for colorectal cancer resection bares early post-operative advantages and results in equal oncologic long-term outcome. However, data on laparoscopic right hemi-colectomy is scarce. Aim of the present study was to analyze a well selected collective of patients with right-sided colon cancer treated open and laparoscopically with regard to peri-operative and long-term outcome. METHODS: We analyzed all patients who underwent right-sided hemi-colectomy for colon cancer between January 1996 and March 2013. Data was extracted from our prospective database. Inclusion criteria were tumor localization in the ascending colon, oncologic resection, histology of an adenocarcinoma, tumors UICC I-III, and R0 resection. Exclusion criteria were multiple malignancies including colon, emergency operation, adenoma or pT0 status, and UICC IV. For the matched pairs approach between patients undergoing laparoscopic (LAP) or open (OPEN) surgery, the parameters age, UICC stage, tumor grading, and sex were applied. RESULTS: A total of 188 patients was included in the analysis with n = 94 in both the LAP and the OPEN group. Some peri-operative results demonstrated advantages for laparoscopy including median return to liquid (p < 0.0001) and solid diet (p = 0.008), median length of ICU stay (p < 0.0001), and median length of hospital stay (p = 0.022). No significant differences were revealed for complication rates, rates of anastomotic leakage, or 30-day mortality. Lymph node yield was identical. Also, no differences in oncologic long-term outcome were detected. Rates for local recurrence were 4.3 and 2.0 %. CONCLUSION: This matched pairs analysis verifies peri-operative advantages of laparoscopy explicitly for the sub-group of CRC patients undergoing right-sided hemi-colectomy in comparison to open surgery while demonstrating equivalent oncologic long-term results.

[An Experimental Set-Up for Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair (Nav-CARS EVAR)]. / Ein Prototyp für die navigierte Implantation von Aortenstentprothesen zur Reduzierung der Kontrastmittel- und Strahlenbelastung: Das Nav-CARS-EVAR-Konzept (Navigated-Contrast-Agent and Radiation Sparing Endovascular Aortic Repair).

INTRODUCTION: Over the last decade endovascular stenting of aortic aneurysm (EVAR) has been developed from single centre experiences to a standard procedure. With increasing clinical expertise and medical technology advances treatment of even complex aneurysms are feasible by endovascular methods. One integral part for the success of this minimally invasive procedure is innovative and improved vascular imaging to generate exact measurements and correct placement of stent prosthesis. One of the greatest difficulty in learning and performing this endovascular therapy is the fact that the three-dimensional vascular tree has to be overlaid with the two-dimensional angiographic scene by the vascular surgeon. MATERIAL AND METHODS: We report the development of real-time navigation software, which allows a three-dimensional endoluminal view of the vascular system during an EVAR procedure in patients with infrarenal aortic aneurysm. We used the preoperative planning CT angiography for three-dimensional reconstruction of aortic anatomy by volume-rendered segmentation. At the beginning of the intervention the relevant landmarks are matched in real-time with the two-dimensional angiographic scene. During the intervention the software continously registers the position of the guide-wire or the stent. An additional 3D-screen shows the generated endoluminal view during the whole intervention in real-time. RESULTS: We examined the combination of hardware and software components including complex image registration and fibre optic sensor technology (fibre-bragg navigation) with integration in stent graft introducer sheaths using patient-specific vascular phantoms in an experimental setting. From a technical point of view the feasibility of fibre-Bragg navigation has been proven in our experimental setting with patient-based vascular models. Three-dimensional preoperative planning including registration and simulation of virtual angioscopy in real time are realised. CONCLUSION: The aim of the Nav-CARS-EVAR concept is reduction of contrast medium and radiation dose by a three-dimensional navigation during the EVAR procedure. To implement fibre-Bragg navigation further experimental studies are necessary to verify accuracy before clinical application.

[Surgical treatment and prognosis of rectovaginal fistulae according to their origin]. / Chirurgische Versorgung und Prognose rektovaginaler Fisteln in Abhängigkeit ihrer Genese.

INTRODUCTION: The rectovaginal fistula is a rare entity with heterogenic causality. Its genesis seems to predict the extent of operative treatment and the prognostic outcome. The aim of this study was to present different surgical techniques in the treatment of rectovaginal fistulas and their results in correspondence to the genesis. MATERIAL AND METHODS: Between 1 / 2000 and 1 / 2010, the data of patients with rectovaginal fistulas were collected. The retrospective analysis included biographic and anamnestic data as well as clinical parameters, general and specific complications and postoperative data. RESULTS: In a timespan of ten years 36 patients with rectovaginal fistulas were treated. The most common causes were inflammatory diseases (n = 21) and earlier surgical measures (n = 6). Moreover tumour-associated fistulas (n = 5) and fistulas with unknown genesis (n = 4) were seen. As surgical techniques anterior resection (n = 21), transrectal flap plasty (n = 7), subtotal colectomy (n = 3), pelvine exenteration (n = 2) and rectal exstirpation (n = 1) were used. The closure of the vaginal lesion was performed by single suture (n = 25), flap plasty (n = 6), transvaginal omental plasty (n = 2) and posterior vaginal plasty (n = 1). All patients were provided with an omental plasty to perform a safe division of the concerned regions. Patients with a low fistula ( < 6 cm) were treated with transperineal omental plasty. The median follow-up was 12 months (6 - 36). Within this timespan 6 patients suffered from major complications [ARDS, anastomosis insufficiency, postoperative bleeding, recurrence of fistula (n = 3)]. Three patients died in the postoperative period (cerebellar infarct, septic complication associated with Crohn's disease, multiorgan failure in tumour recurrence). CONCLUSION: The genesis of rectovaginal fistulae is an important predictor for the size of resection which can range from simple excision to exenteration. For optimal therapy the surgical intervention needs to be integrated into an interdisciplinary therapy concept.

Transperineal omentum flap for the anatomic reconstruction of the rectovaginal space in the therapy of rectovaginal fistulas.

AIM: Deep rectovaginal fistulas are a rare entity and pose a delicate challenge for the surgeon. The present study introduces different operative interventions involved in transperineal omental flap surgery. METHOD: A retrospective analysis of all patients treated with a low or mid rectovaginal or enterovaginal fistula at the Department of Surgery of the University Hospital of Schleswig-Holstein, Campus Luebeck, was performed. Treatment results were discussed with respect to aetiology, localization, morbidity and outcome. RESULTS: Between the years 2000 and 2010, a total of nine patients with a low or mid rectovaginal fistula were treated at our clinic. After local fistulectomy, all patients were additionally treated by a laparoscopically assisted omental flap reconstruction of the rectovaginal and perineal space. Eight of the nine patients received a protective ileostomy or colostomy. Only the patient with a history of Crohn's disease had no ileostomy raised. At a median follow-up of 22 months, no patient experienced recurrence of a rectovaginal fistula. Perioperative mortality was zero and minor complications were observed in 22%. Major complications were an anastomotic insufficiency after low anterior resection that was treated without further interventions. Another complication was a persistent fistula within the sphincter that needed re-operation and bovine plug repair combined with a mucosa flap. CONCLUSIONS: Complete omental reconstruction of the rectovaginal space appears decisive in the operative therapy of deep rectovaginal or enterovaginal fistulas. Comparative studies on standard therapies are necessary although direct comparison of case series is difficult.

Stoma formation for fecal diversion: a plea for the laparoscopic approach.

BACKGROUND: The aim of this study was to assess the results of laparoscopic stoma creation for fecal diversion, specifically focussing on feasibility, safety, and efficacy, as well as indications and techniques. METHODS: Within a 10-year-period, all patients requiring laparoscopic stoma creation were evaluated prospectively. Patients' profiles and indications, procedures and results of operation, conversion, morbidity, mortality and short-term complications (stoma-related, laparoscopy-associated) were analyzed. RESULTS: A total of 80 patients (39 males, 41 females) with a mean age of 55.5 years (range, 17-91) underwent laparoscopic stoma creation. Most common indications were unresectable advanced colorectal cancer (n=20), pelvic malignant cancer (e. g. ovarian, cervix and prostate cancer, n=16), and perianal Crohn's disease with complex fistulas (n=16). Only in one female patient with pelvic malignant disease was the procedure converted to laparotomy due to obesity (conversion rate, 1.3%). 79 patients underwent laparoscopic stoma creation (completion rate, 98.7%) including loop ileostomy (n=30), loop sigmoid colostomy (n=40) and end sigmoid colostomy (n=9). Postoperative complications were documented in 9 patients (overall morbidity rate, 11.4%), including 4 minor complications treated conservatively (2 cases of prolonged atonia and 1 case each of pneumonia and urinary tract infection) and 5 major complications requiring reoperation (reoperation rate, 6.3%): one parastomal abscess (drainage), one stoma retraction following rod dislocation (laparoscopic stoma recreation), small bowel obstruction in two patients (small bowel resection), one port-site hernia (fascial closure), and hemorrhage (managed by re-laparoscopy). Mean operation time was 74 min (range, 30-245 min). Mean blood loss volume was 80 ml (range, 30-400 ml). Patients were discharged from hospital after a mean of 10.3 days (range, 3-47). Within a 1-year follow-up, no further stoma complications were documented. CONCLUSIONS: The advantages of laparoscopic stoma creation are low morbidity and reoperation rates, and no procedure-related mortality; our results suggest that laparoscopic stoma creation for fecal diversion is safe, feasible and effective. Therefore, at our institution, laparoscopic stoma creation is the method of choice for fecal diversion.

[Therapy of intraabdominal fungal infections]. / Therapie der intraabdominellen Pilzinfektionen.

Candida albicans is the fourth most germ that can be identified on surgical intensive care unit (SICU). During the course of severe peritonitis recognition of Candida is crucial for physicians but interpretation of Candida-positive microbiologic samples is difficult. The indication for antimycotic therapy requires differentiation between harmless contamination or severe invasive mycosis associated with high mortality. Therefore, we propose a four-stage classification. Stage I is the initial contamination of the abdominal cavity by Candida spp. Stage IIa is characterized by persistence of fungi in patients without risk factors, IIb with risk factors respectively. Stage III means histological evidence of Candida invasion into the peritoneal layer. Stage IV is a generalized infection with fungemia/fungal sepsis. We recommend antimycotic therapy in stage IIb or higher.

[Ultrasound-guided interventions using magnetic field navigation. First experiences with Ultra-Guide 2000 under operative conditions]. / Ultraschallgesteuerte Interventionen unter virtueller Führung. Erste Ergebnisse mit dem US-Guide 2000 unter operativen Bedingungen.

AIM: Ultrasound-guided interventions are presently performed as free-hand-type procedures or using biopsy transducers. In this article we report on our experience with a new navigation-system for sonographically guided interventional procedures under OR-conditions. METHODS: The US-Guide 2000 trade mark is an electromagnetic guidance system that assists physicians in ultrasound-guided interventional procedures. This system accommodates both in-plane and out-of-plane needle placement. We evaluated this system for the first time under OR-conditions. Overall, for 39 interventional procedures (23 thermoablations of malignant liver lesions, 16 diagnostic punctures) were performed. RESULTS: All targets were reached successfully without any complications. No interactions with other OR-devices were seen. CONCLUSION: The US-Guide 2000 trade mark as a virtual needle-guiding system allows a safe and accurate sonographically assisted intervention. The major advantage is the possibility of out-of-plane needle placement and the combination of flexibility of free-hand-type procedures with the accuracy of a biopsy transducer. This increases the safety of punctures especially when lesions are difficult to reach and/or are situated next to vulnerable structures. It also reduces the interventional trauma.

Pouch reconstruction in the pelvis.

ILEAL POUCH RECONSTRUCTION: Proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the procedure of choice in mucosal ulcerative colitis (MUC) and familial adenomatous polyposis (FAP). Because the disease is cured by surgical resection, functional results, pouch survival prognosis, and disease or dysplasia control are the major determinants of success. There is controversy as to whether the IPAA should be handsewn with mucosectomy or stapled, preserving the mucosa of the anal transitional zone. Crohn's disease is a contraindication for IPAA, but long-term outcome after IPAA is similar to that for MUC in patients with indeterminate colitis who do not develop Crohn's disease. As development of dysplasia and cancer in the ileal pouch have been reported, a standardized surveillance program is mandatory in cases of MUC, FAP, and chronic pouchitis. COLONIC POUCH RECONSTRUCTION: Construction of a colonic pouch is a widely accepted technique to improve functional outcome after low or intersphincteric resection for rectal cancer. Several randomized studies comparing colo-pouch-anal anastomosis (CPA) with straight coloanal anastomosis (CAA) have found the pouch functionally superior. Most controlled studies cover only 1-year follow-up, but randomized studies with 2-year follow-up show similar functional results of CPA and CAA. Evacuation difficulty as initially observed was related to pouch size, and the results with smaller pouches (5-6 cm) are more favorable, showing adequate reservoir function without compromising neorectal evacuation. The transverse coloplasty pouch may offer several advantages to J-pouch reconstruction. Current series question whether the neorectal reservoir is the physiological key of the pouch, but rather the decreased motility. The major advantage reported with colonic pouch reconstruction is the lower incidence of anastomotic complications.

Metabolic changes detected by microdialysis during endotoxin shock and after endotoxin preconditioning.

OBJECTIVE: Preconditioning with low doses of endotoxin has been shown to induce endotoxin hyporesponsiveness. The present study was designed to assess the metabolic response of various tissues during endotoxemia and after pretreatment with endotoxin. DESIGN: Controlled experimental animal study. SETTING: Research laboratory of a university hospital. MEASUREMENTS AND RESULTS: Ten pigs were randomly assigned to a control ( n = 5) or a treatment group ( n = 5), the latter receiving incremental doses of endotoxin 5-2 days prior the experiments. Apart from hemodynamics and oxygen transport variables, lactate, glucose, and glycerol were measured in muscle, subcutaneous fat, and hepatic tissue using microdialysis. Endotoxin was infused (1 micro g.kg.h) until the animals died. A significant increase in tissue lactate (eightfold) and glycerol (fivefold) was observed in the control animals. This effect was almost completely abolished in the endotoxin pretreated group. Endotoxin pretreatment had no significant effects on mean arterial pressure [56 (range 34-89) mmHg vs 70 (47-88) mmHg, n.s.] or cardiac output [4.8 (3.0-5.9) l/min vs 3.2 (2.1-4.2) l/min, n.s.], but significantly improved arterial pO(2) and pH ( P<0.05). Increase of oxygen extraction was higher in control animals [from 34% (range 24-47%) to 72% (range 61-79%)] compared to the pretreatment group [from 30% (range 22-42%) to 44% (range 34-50%), P<0.05]. Endotoxin pretreatment increased survival time from 5.3 h (5.0-5.8) to 8.0 h (7.0-8.5) ( P<0.05), respectively. CONCLUSIONS: Microdialysis monitoring revealed that endotoxin preconditioning ameliorates the increase in tissue metabolism during endotoxemia, accompanied by decreased systemic oxygen demand despite unchanged global hemodynamics.