Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

The Lages diatremes: mineral composition and petrological implications

Chemical data of heavy minerals from Lages diatremes in southern Brazil have been studied with the aim of characterizing the sample source(s). Three groups of minerals are recognized: I) aluminian-chromian pyroxene, pyrope garnet and chromian spinel, which represent disaggregated fragments of spinel, spinel+garnet and garnet facies peridotite; II) low-Cr aluminian pyroxene that occurs as megacrysts are high pressure phases (7-12 kb) being crystallized from an alkaline-like evolving magma; III) low-Cr aluminian diopside of crustal origin. Evidence of carbonatitic cryptic metasomatic enrichment is shown by clinopyroxenes of Groups I and II. The data do not support a kimberlitic affinity as it has been suggested for the diatremes. Rather, they are interpreted as vents related to the alkaline magmatism affecting the area in Late Cretaceous. The alkaline parental magma of the pyroxene megacrysts was generated from a metasomatized mantle at garnet facies that incorporated fragments of the surrounding still fertile mantle. Presumably at spinel-facies level the magma began to fractionate the megacrysts, whose crystallization proceeded over a large range of falling pressure and temperature. The chemical similarities between Group III clinopyroxenes and those from the differentiated lithotypes indicate that the magma carried this mineral phase on its evolution, at crustal conditions, towards a more evolved alkaline composition. Still, a non-cognate origin for the Group III clinopyroxenes cannot be discarded.<br>Dados químicos de minerais pesados dos diatremas de Lages no sul do Brasil foram estudados com o propósito de caracterizar as fontes das rochas. Três grupos de minerais são reconhecidos: I) piroxênio aluminoso-cromífero, granada piropo e espinélio cromífero, representando fragmentos desagregados de espinélio, espinélio+granada e granada da fácies peridotito; II) piroxênio aluminoso com baixo Cr, correspondendo a megacristais, com as fases de alta pressão (7-12 kb) cristalizadas a partir de magma alcalino em evolução; III) diopsídio aluminoso com baixo Cr e origem crustal. Clinopiroxênios dos Grupos I e II mostram evidências de enriquecimento metassomático críptico de natureza carbonatítica. Os dados não confirmam a afinidade kimberlítica sugerida para esses diatremas. Ao contrário, eles são interpretados como condutos relacionados ao magmatismo alcalino que afetou a área no Cretáceo Superior. O magma parental alcalino dos megacristais de piroxênio foi originado a partir de um manto metassomatizado na fácies granada que aprisionou fragmentos do ainda fértil manto adjacente. Presumivelmente na fácies espinélio teve início o fracionamento dos megacristais, cuja cristalização se deu em condições de pressão e temperatura decrescentes. As similaridades entre os clinopiroxênios do Grupo III e aqueles dos litotipos mais diferenciados sugere que essa fase mineral foi transportada pelo magma no curso de sua evolução, em condições crustais, para uma composição alcalina mais evoluída. Ainda, uma formação não-cogenética para os clinopiroxênios do Grupo III não pode ser descartada