Evaluation of dispersion models DIPCOT and RIMPUFF used in Decision Support Systems for nuclear and radiological emergency response

This paper presents evaluation of the atmospheric dispersion models DIPCOT and RIMPUFF which are incorporated for operational use in Decision Support Systems for nuclear emergencies. The evaluation is performed through comparisons of model results with real-scale measurements of gamma radiation dose rates in air obtained during the routine operation of the HIFAR Research Reactor located in Sydney, Australia. The area surrounding the reactor is characterized by moderately complicated topography and varying land cover. A total of 16 days have been computationally simulated, covering all atmospheric stability conditions. Qualitative and quantitative model evaluation is carried out, using comparisons of paired in space and time calculated and measured gamma dose rates, statistical indices, scatter plots, and contour plots. The models performance is satisfactory for a number of cases, while for others the performance is poor. This can be attributed to a number of factors, mainly uncertainties in the prediction of meteorological conditions

Surgical Therapy of Hepatocellular Carcinoma: State of the Art Liver Resection

Hepatocellular carcinoma (HCC) represents the third most common cause of cancer-related death, showing incremental growth rates throughout the last decades. HCC requires multidisciplinary approach in a group of patients suffering from underlying chronic liver disease, usually in the setting of cirrhosis. The mainstay of treatment in resectable cases is surgery, with anatomic and non-anatomic liver resections widely implemented, as well as liver transplantation in well-selected individuals. Nowadays, there is a variety of liver parenchyma transection devices used by hepatobiliary surgeons in specialized centers, which has significantly improved postoperative outcomes in HCC patients. Therefore, hepatectomy is considered safe and feasible and should be the main therapeutic option for HCC patients, candidates for resection. Liver resection utilizing cavitron ultrasonic aspirator in combination with bipolar radiofrequency ablation is safe and effective for the treatment of HCC with favorable clinical and oncological outcomes

30-day morbidity and mortality of sleeve gastrectomy, Roux-en-Y gastric bypass and one anastomosis gastric bypass: a propensity score-matched analysis of the GENEVA data

Background: There is a paucity of data comparing 30-day morbidity and mortality of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one anastomosis gastric bypass (OAGB). This study aimed to compare the 30-day safety of SG, RYGB, and OAGB in propensity score-matched cohorts. Materials and methods: This analysis utilised data collected from the GENEVA study which was a multicentre observational cohort study of bariatric and metabolic surgery (BMS) in 185 centres across 42 countries between 01/05/2022 and 31/10/2020 during the Coronavirus Disease-2019 (COVID-19) pandemic. 30-day complications were categorised according to the Clavien–Dindo classification. Patients receiving SG, RYGB, or OAGB were propensity-matched according to baseline characteristics and 30-day complications were compared between groups. Results: In total, 6770 patients (SG 3983; OAGB 702; RYGB 2085) were included in this analysis. Prior to matching, RYGB was associated with highest 30-day complication rate (SG 5.8%; OAGB 7.5%; RYGB 8.0% (p = 0.006)). On multivariate regression modelling, Insulin-dependent type 2 diabetes mellitus and hypercholesterolaemia were associated with increased 30-day complications. Being a non-smoker was associated with reduced complication rates. When compared to SG as a reference category, RYGB, but not OAGB, was associated with an increased rate of 30-day complications. A total of 702 pairs of SG and OAGB were propensity score-matched. The complication rate in the SG group was 7.3% (n = 51) as compared to 7.5% (n = 53) in the OAGB group (p = 0.68). Similarly, 2085 pairs of SG and RYGB were propensity score-matched. The complication rate in the SG group was 6.1% (n = 127) as compared to 7.9% (n = 166) in the RYGB group (p = 0.09). And, 702 pairs of OAGB and RYGB were matched. The complication rate in both groups was the same at 7.5 % (n = 53; p = 0.07). Conclusions: This global study found no significant difference in the 30-day morbidity and mortality of SG, RYGB, and OAGB in propensity score-matched cohorts

30-Day morbidity and mortality of bariatric metabolic surgery in adolescence during the COVID-19 pandemic – The GENEVA study

Background: Metabolic and bariatric surgery (MBS) is an effective treatment for adolescents with severe obesity. Objectives: This study examined the safety of MBS in adolescents during the coronavirus disease 2019 (COVID-19) pandemic. Methods: This was a global, multicentre and observational cohort study of MBS performed between May 01, 2020, and October 10,2020, in 68 centres from 24 countries. Data collection included in-hospital and 30-day COVID-19 and surgery-specific morbidity/mortality. Results: One hundred and seventy adolescent patients (mean age: 17.75 ± 1.30 years), mostly females (n = 122, 71.8%), underwent MBS during the study period. The mean pre-operative weight and body mass index were 122.16 ± 15.92 kg and 43.7 ± 7.11 kg/m2, respectively. Although majority of patients had pre-operative testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (n = 146; 85.9%), only 42.4% (n = 72) of the patients were asked to self-isolate pre-operatively. Two patients developed symptomatic SARS-CoV-2 infection post-operatively (1.2%). The overall complication rate was 5.3% (n = 9). There was no mortality in this cohort. Conclusions: MBS in adolescents with obesity is safe during the COVID-19 pandemic when performed within the context of local precautionary procedures (such as pre-operative testing). The 30-day morbidity rates were similar to those reported pre-pandemic. These data will help facilitate the safe re-introduction of MBS services for this group of patients

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Air pollution simulation over complex terrain using Lagrangian particle model based on Langevin equation

Air quality management is substantially based on dispersion models for the assessment of the air pollution. Atmospheric dispersion models are used to assess the effects of air pollutants to aid emergency response in cases of accidental releases or to assist in decisions during the design phase of a certain unit. The aim of this dissertation was to develop a model appropriate for the simulation of inert gases dispersion over complex topographies. The models should be able to handle the transfer of pollutants from some kilometers around the source (short-range) to several hundred (mesoscale) or thousands of kilometers (long-range), taking into account the topographical features of the domain. It was essential that dispersion calculations can be performed with the minimum available information with small computational cost. […]Τα προβλήματα ρύπανσης έχουν οδηγήσει στην ανάπτυξη και χρήση υπολογιστικών δομών που έχουν ως στόχο τη μοντελοποίηση της διασποράς αερίων ρύπων. Τέτοια μοντέλα ενσωματώνονται σε ολοκληρωμένα συστήματα παρακολούθησης και πρόβλεψης της τυρβώδους διάχυσης αερίων ρύπων στην ατμόσφαιρα. Σκοπός της διαδικασίας αυτής είναι ο έλεγχος της ρύπανσης και η λήψη πιθανών μέτρων για την προστασία των πολιτών, τόσο σε περιπτώσεις ατυχημάτων μεγάλης έκτασης, όσο και σε συνθήκες πραγματικής λειτουργίας βιομηχανικών μονάδων. Βασικό αντικείμενο της διατριβής ήταν να αναπτυχθεί ένα μοντέλο διασποράς κατάλληλο για προσομοίωση της διασποράς αδρανών αερίων ρύπων πάνω από περίπλοκες τοπογραφίες. Στόχος ήταν το μοντέλο να είναι ευέλικτο, να έχει τη δυνατότητα εφαρμογής ακόμα και με την ελάχιστη δυνατή πληροφορία, και να δίνει όσο το δυνατόν καλύτερες προβλέψεις. […

Minimally invasive transcervical esophagectomy with mediastinal lymphadenectomy for cancer. A Comparison with standardized techniques

Εισαγωγή/Σκοπός Η χειρουργική παραμένει πρωτοπόρος στον αλγόριθμο της θεραπείας του καρκίνου του οισοφάγου. Συγκεκριμένα, η οισοφαγεκτομή δύο σταδίων (Ivor Lewis) ή τριών σταδίων (McKeown), η οποίες συνδυάζουν κοιλιακή και θωρακική προσπέλαση, είναι η επεμβάσεις εκλογής παγκοσμίως για τη θεραπεία του καρκίνου του μέσου ή κατώτερου οισοφάγου, καθώς και της καρδιο-οισοφαγικής συμβολής. Η διαθωρακική οισοφαγεκτομή όμως, έχει διαχρονικά συσχετιστεί με αυξημένα ποσοστά μετεγχειρητικής νοσηρότητας, κυρίως αναπνευστικών επιπλοκών. Η ελάχιστα επεμβατική οισοφαγεκτομή προσφέρει αξιοσημείωτη βελτίωση στα κλινικά αποτελέσματα των ασθενών που υποβάλλονται σε οισοφαγεκτομή καθώς και σημαντική μείωση των αναπνευστικών επιπλοκών σε σχέση με την ανοικτή οισοφαγεκτομή. Η ελάχιστα επεμβατική διατραχηλική οισοφαγεκτομή με ταυτόχρονο λεμφαδενικό καθαρισμό του μεσοθωρακίου αποφεύγει την είσοδο στο θώρακα, κάτι το οποίο μπορεί περεταίρω να μειώσει τις αναπνευστικές επιπλοκές σε σχέση με τις άλλες τεχνικές ελάχιστα επεμβατικής οισοφαγεκτομής. Υλικό και Μέθοδος Η μέθοδος αυτή αναφέρεται σε διατραχηλική κινητοποίηση του οισοφάγου με συνοδό λεμφαδενικό καθαρισμό του ανωτέρου και μέσου μεσοθωρακίου, ακολουθούμενη από διακοιλιακό-διασκελιάιο ολοκλήρωση της κινητοποίηση του κατώτερου θωρακικού οισοφάγου, λεμφαδενικού καθαρισμού στην άνω κοιλία και το κατώτερο μεσοθωράκιο αλλά και προετοιμασία και διατομή του στομάχου για αποκατάσταση της συνέχειας του πεπτικού. Αποτελέσματα H υιοθέτηση των ελάχιστα επεμβατικών τεχνικών στην διατραχηλική προσπέλαση, όπως η λαπαροσκόπηση/θωρακοσκόπηση ή η ρομποτική θωρακοσκόπηση έχουν κάνει εφικτή την ριζική λεμφαδενική κένωση του μεσοθωρακίου και κατ’ επέκταση την ριζική οισοφαγεκτομή. Αυτή η πρωτοπόρος χειρουργική προσέγγιση με αποφυγή της θωρακοτομής ή θωρακοσκόπησης επιτρέπει την πρόσβαση στο μεσοθωράκιο χωρίς αποκλεισμό του ενός πνεύμονα (δεξιού), όπως συμβαίνει στην διαθωρακική οισοφαγεκτομή. Ασθενείς με προηγούμενες επεμβάσεις στο θώρακα, ασθενείς με μείζονα αναπνευστική ανεπάρκεια ή επιβαρυντικές συνοσηρότητες που δεν είναι δυνατό να υποβληθούν σε διαθωρακική οισοφαγεκτομή, έχουν πλέον την πρόσβαση σε μια επέμβαση ριζική, χωρίς εκπτώσεις στην έκταση της λεμφαδενικής κένωσης. Συμπέρασμα Η ελάχιστα επεμβατική διατραχηλική οισοφαγεκτομή με ταυτόχρονη λεμφαδενική κένωση του μεσοθωρακίου για καρκίνο είναι μια ασφαλής και εφικτή χειρουργική προσέγγιση η οποία προσφέρει κλινικά και ογκολογικά αποτελέσματα σε βάθος χρόνου.Background/Aim Pulmonary complications remain the most common problem following transthoracic esophagectomy for the treatment of esophageal and gastro-esophageal junction cancer. Minimally invasive approach has significantly improved clinical outcomes; however, respiratory distress is still significant. Minimally invasive transcervical esophagectomy avoids thoracic access, which may provide a decrease in pulmonary complications after esophagectomy. Material and Methods Transcervical esophagectomy refers to transcervical esophageal mobilization and mediastinal lymphadenectomy followed by a transhiatal gastric and distal-esophageal mobilization, abdominal and lower mediastinal lymphadenectomy. Adoption of innovative minimally invasive techniques for the transcervical or transhiatal approach, such as laparoscopy or robotic-assisted mediastinoscopy have made possible radical transmediastinal approach for radical esophagectomy. Results This novel approach with avoidance of thoracotomy or thoracoscopy can omit one lung ventilation as in transthoracic esophagectomy. Patients with previous thoracic surgery, impaired respiratory system and major comorbidities which were unable to undergo transthoracic esophagectomy become candidates for radical esophagectomy with promising results. Conclusion Minimally invasive transcervical esophagectomy is a safe and feasible approach and may act as a valuable alternative to open or minimally invasive transthoracic esophagectomy, with no thoracic access, minimal thoracic trauma, lower rates of pulmonary complications, and favorable clinical and oncological outcomes