Mild chemical h-insertion into gamma-manganese dioxides

About a hundred samples of y-manganese dioxide covering three materials coded SBP- A, Faradiser M and R2 have been reduced chemically by insertion of H through controlled additions of hydrazine hydrate solutions at about 1 °C. The H-inserted samples and the starting materials were subjected to chemical analysis for oxidation state, X-ray diffraction (XRD) for structure study and Fourier Transform Infrared (FTIR) spectroscopy to gain information on OH bonding. Additional techniques including FTIR spectroscopy at low temperature (~ -180 °C), electrode potential measurement and scanning electron microscopy (SEM) have also been applied. The intergrowth structure of the starting materials consisted of ramsdellite intercepted with pyrolusite layers, known as de Wolff faults, and quantified by the fraction of pyrolusite layers Pr. An additional structural parameter for these materials was the amount of micro twinning (Tw) across the 021/061 ramsdellite planes. This parameter, introduced by Pannetier, is given in percent. Values of (Pr , Tw) have been given as (0.41 , 17) for SBP-A, (0.70,10) for Faradiser M and (0.41, ~100) for R2. Upon H-insertion, the structure of the starting materials expanded homogeneously in a direction and to an extent which depended on the Pr and Tw parameters. Faradiser M, with high Pr and very low Tw, expanded homogeneously in the direction of the b lattice dimension up to an insertion level of 0.69 of s in MnOn/Hs. Above this level, the initial structure changed suddenly into the structure of the final product: the insertion then proceeded homogeneously in the new phase. The main changes were an expansion of the octahedra and a rotation leading to hinged tunnels. This is the first time that the existence of two solid solutions in the MnO2/H system has been noted. With SBP-A, the amount of microtwinning restricted the homogeneous expansion of SBP-A to s = 0.28, which occurred predominantly in the a direction. Further insertion broke the twinning boundary and formed a demicrotwinned phase of composition MnOn Ho.68 in which the tunnels were also hinged. Thereafter H-insertion proceeded heterogeneously from 0.28 to 0.68 in s. Above s = 0.68, the structure developed homogeneously towards that of the fully H-inserted product. The extensive microtwinning in R2 allowed for a homogeneous expansion, thought to be isotropic to maintain the microtwinned structure, up to s = 0.39. Higher insertion levels led to the expansion to proceed heterogeneously to a composition of MnOn Ho.63. Above s = 0.63, a new phase, the final product, was formed with fully demicrotwinned structure and fully hinged tunnels. R-insertion into y-manganese dioxide has never been reported to occur in three stages previously. The FTIR study at room temperature has shown absence of OH bond vibrations at insertion levels prior to the hinging of the tunnels, in contrast to their presence after the structure has rotated and the tunnels had hinged. This is seen as a strong indication of H mobility in the initial structure. The hinging is necessary for OH bonding as it brings the 02 and 01 oxygens closer allowing the proton to bond both covalently and by H-bonding. At low temperature, initially mobile hydrogen could be trapped and OR bonds formed only in H-inserted R2. This was linked to 061-microtwinning. The absence of OH bonds at low temperature in SBP-A and Faradiser M led to the conclusion that these materials have no 061 micro twinning faults. The absence of OH bonds at low temperature in the starting materials, particularly in R2, strongly questions the postulated OH groups in the structure of y-MnO2, according to the cation vacancy model. Electrode potential data supported the above conclusions in terms of the stages of the H-insertion. The battery activity of the materials seemed to be related to the extent at which the materials kept the initial structure with non-hinged tunnels. Comparison with previous works on the same materials suggested that the differences could be accounted for by the kinetics of the H-insertion. While protons in this work were released spontaneously on the surface of the MnO x , their diffusion into the bulk was slow due to the low temperature. In the compared literature, the reverse applies

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Pooled analysis of who surgical safety checklist use and mortality after emergency laparotomy

Background: The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods: In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results: Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89⋅6 per cent) compared with that in countries with a middle (753 of 1242, 60⋅6 per cent; odds ratio (OR) 0⋅17, 95 per cent c.i. 0⋅14 to 0⋅21, P &lt; 0⋅001) or low (363 of 860, 42⋅2 percent; OR 0⋅08, 0⋅07 to 0⋅10, P &lt; 0⋅001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference −9⋅4 (95 per cent c.i. −11⋅9 to −6⋅9) per cent; P &lt; 0⋅001), but the relationship was reversed in low-HDI countries (+12⋅1 (+7⋅0 to +17⋅3) per cent; P &lt; 0⋅001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0⋅60, 0⋅50 to 0⋅73; P &lt; 0⋅001). The greatest absolute benefit was seen for emergency surgery in low-and middle-HDI countries. Conclusion: Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries

Mortality of emergency abdominal surgery in high-, middle- and low-income countries

Background: Surgical mortality data are collected routinely in high-income countries, yet virtually no low- or middle-income countries have outcome surveillance in place. The aim was prospectively to collect worldwide mortality data following emergency abdominal surgery, comparing findings across countries with a low, middle or high Human Development Index (HDI). Methods: This was a prospective, multicentre, cohort study. Self-selected hospitals performing emergency surgery submitted prespecified data for consecutive patients from at least one 2-week interval during July to December 2014. Postoperative mortality was analysed by hierarchical multivariable logistic regression. Results: Data were obtained for 10 745 patients from 357 centres in 58 countries; 6538 were from high-, 2889 from middle- and 1318 from low-HDI settings. The overall mortality rate was 1⋅6 per cent at 24 h (high 1⋅1 per cent, middle 1⋅9 per cent, low 3⋅4 per cent; P < 0⋅001), increasing to 5⋅4 per cent by 30 days (high 4⋅5 per cent, middle 6⋅0 per cent, low 8⋅6 per cent; P < 0⋅001). Of the 578 patients who died, 404 (69⋅9 per cent) did so between 24 h and 30 days following surgery (high 74⋅2 per cent, middle 68⋅8 per cent, low 60⋅5 per cent). After adjustment, 30-day mortality remained higher in middle-income (odds ratio (OR) 2⋅78, 95 per cent c.i. 1⋅84 to 4⋅20) and low-income (OR 2⋅97, 1⋅84 to 4⋅81) countries. Surgical safety checklist use was less frequent in low- and middle-income countries, but when used was associated with reduced mortality at 30 days. Conclusion: Mortality is three times higher in low- compared with high-HDI countries even when adjusted for prognostic factors. Patient safety factors may have an important role. Registration number: NCT02179112 (http://www.clinicaltrials.gov)

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Rétinoblastome du grand enfant : à propos de 4 observations

Introduction : Le rétinoblastome(RB) est la tumeur oculaire maligne la plus fréquente de l’enfant. Il est très rare après l’âge de 5 ans. Le diagnostic se fait habituellement à l’âge de 2 ans pour les formes unilatérales et à 1 an pour les formes bilatérales. L’objectif de ce travail est de déterminer les caractéristiquesépidémiologiques, cliniques et thérapeutiquesdu rétinoblastome chez le grand enfant (≥ 5 ans) à travers quatre observations de patients suivis pour rétinoblastome unilatéral âgés respectivement de 6 ans, 6 ans et demi, 10 ans et 14 ans