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

Studies on optimisation of collimator thickness and aperture for hot spot identification system using Monte Carlo technique

874-875The optimum collimator design in terms of aperture and thickness for accomplishing improved performance for wide energy radiation field has been investigated in the present paper. A 2"2" NaI(Tl) detector was used as sensor in proposed Hot Spot Identification system. The spectral response of the detector with various collimator apertures and thickness was developed using Monte Carlo methods for optimizing the collimator design. The optimum size of collimator aperture is found to be 2 mm and thickness of 5 cm. Studies were also carried out to optimize lead shield thickness around the detector. </span

Studies on optimization of moderator thickness for BF₃ detectors used for monitoring of fissile material

811-813Monitoring of fissile material content in waste drums requires an energy independent neutron response due to the inherent moderation of neutrons in the waste matrix. For this purpose, a detector assembly consisting of three BF3 detectors each 100 cm long and covered with 3.7 cm thick HDPE moderators arranged in a linear geometry has been set-up. The response of the assembly as measured using different neutron sources was observed to be appropriate within acceptable limits. Response of the detector assembly to a 252Cf source which has a fission neutron spectrum similar to that of fissile materials was measured and compared with the FLUKA based simulations. The sensitivity of the system as evaluated using FLUKA simulations for a 252Cf neutron source was found to be in good agreement with the experimental values. This study indicates that the optimum range of moderator thickness for effective monitoring of fissile material using BF3 neutron detector assembly is 6-7 cm

Cerebrospinal fluid cytokines and matrix metalloproteinases in human immunodeficiency seropositive and seronegative patients of tuberculous meningitis

Background: Some important clinical differences exist between human immunodeficiency virus (HIV)-seropositive and HIV-seronegative patients. Alterations in the cerebrospinal fluid (CSF) cytokines and matrix metalloproteinase have been noted in tuberculous meningitis. In HIV-infected patients, the immunopathogenesis is expected to be different. Materials and Methods: In this study, 64 patients of tuberculous meningitis (28 HIV seropositive and 36 seronegative) were included. The patients were followed up for six months. Cerebrospinal fluid (CSF) samples of tuberculous meningitis patients and 20 controls were subjected to tissue necrosis factor (TNF)-α, interleukin (IL)-1β, interferon (IFN)-γ, IL-10, matrix metalloproteinase (MMP)-2, and MMP-9 estimations. The levels were correlated with the patients′ baseline clinical characteristics, CSF parameters, neuroimaging findings, and the outcome. The outcome was assessed and modified with the Barthel index. Results: The CSF cytokines and MMP levels were significantly elevated in tuberculous meningitis when compared with the controls. There was no significant difference seen between HIV seropositive and seronegative tuberculous meningitis, except for the IL-1β level, which was significantly lower in the HIV-infected patients. The cytokine and MMP levels did not correlate with the baseline clinical characteristics, disease severity, cerebrospinal fluid characteristics, neuroimaging findings, and outcome. Conclusion: In conclusion, HIV infection did not affect a majority of the CSF cytokines and MMP levels in tuberculous meningitis except for IL-1β level. None of the estimated inflammatory parameters correlated with the outcome