Evaluation of transcranial Doppler use in patients with acute liver failure listed for emergency liver transplantation

PURPOSE

Acute liver failure (ALF) is characterized by hepatic encephalopathy (HE) often due to intracranial hypertension (ICH). The risk/benefit-balance of intraparenchymal pressure catheter monitoring is controversial during ALF.

AIMS

Perform an evaluation of transcranial Doppler (TCD) use in patients with ALF listed for emergency liver transplantation.

MATERIAL AND METHODS

Single center retrospective cohort study including all patients registered on high emergency LT list between 2012 and 2018. All TCD measurements performed during ICU stay after listing and after LT (when performed) were recorded. TCD was considered abnormal when pulsatility index (PI) was >1.2.

RESULTS

Among 106 patients with ALF, forty-seven (44%) had a TCD while on list. They had more severe liver and extrahepatic organ failure. When performed, TCD was abnormal in 51% of patients. These patients more frequently developed ICH events (45% vs. 13%, p = .02) and more frequently required increase in sedative drugs and vasopressors. While 22% of patients with normal TCD spontaneously survived, all of those with abnormal TCD died or were transplanted (p = .02). All transplanted patients who had abnormal exams normalized their TCD within 2 (1-2) days after LT.

CONCLUSION

TCD may be a useful non-invasive tool for ICH detection and management, then guide sedation withdrawal.

Experimental determination and simulation of neutron and gamma flux parameters in horizontal channel for Prompt Gamma Neutron activation analysis implementation at Es-Salam research reactor

Since 2004, the k₀-standardization method has been applied and evaluated in three experimental channels at Es-Salam research reactor of the Algerian Centre de Recherche Nucléaire de Birine (CRNB). The NAA laboratory at CRNB is well involved in the implementation of the Prompt Gamma Neutron Activation Analysis to extend the field of analyses to some additional elements to the NAA method. In the frame work of the PGNAA research project, several works have been carried out in the present study including the experimental and simulation characterization of neutron and gamma flux parameters of the horizontal channel. The absolute and relative neutron fluxes of the studied channel have been determined by using a set of monitors including Al, Au, Cu, Fe and Zr. Furthermore, measurements of gamma and thermal neutron doses have been achieved using LiF: Mg, Ti (TLD 600 and TLD 700) detectors. The gamma dose rate at the experimental channel center position was found to be 0.6 Gy/min·MW. The experimental results obtained in this study have been used as input information for simulations and design of neutron facilities and radiation shielding, which are successfully established by SCALE code. The results were compared in terms of spectral detail and precision and a good agreement has been revealed. The value of the thermal neutron flux was found to be (6.29 ± 0.25) E+08 n/cm².s which allows the implementation of PGNAA at the Es-Salam research reactor.

Yellow fever cases in French Guiana, evidence of an active circulation in the Guiana Shield, 2017 and 2018

French Guiana (FG) is a French overseas region bordering Brazil and Suriname that is considered endemic for yellow fever (YF); vaccination is compulsory for residents and travellers. In August 2017 and 2018, two sporadic YF cases were notified 1 year apart, confirming that sylvatic YF virus circulation is active in the region. YF vaccination coverage should be closely monitored and improved in FG and neighbouring territories and clinicians should be aware of the risk.

Neutron tomography simulation by MAVRIC/Monaco code

In this study, MAVRIC/Monaco module integrated with SCALE6.1 package is used to elucidate experimental neutron transmission for various neutron-absorbing materials. Neutron beam hardening and its effect on shielding calculation and tomographic image reconstruction accuracy are presented. The experimental data for studied materials are used for comparison purpose and to prove the capability of MAVRIC/Monaco code in neutron tomography simulation. The good agreement between experimental and calculated values confirms the capability of SCALE6.1 package in obtaining physical data exactly analogous to an experimental measurement.

New analytical approach for neutron beam-hardening correction

In neutron imaging, the beam-hardening effect has a significant effect on quantitative and qualitative image interpretation. This study aims to propose a linearization method for beam-hardening correction. The proposed method is based on a new analytical approach establishing the attenuation coefficient as a function of neutron energy. Spectrum energy shift due to beam hardening is studied on the basis of Monte Carlo N-Particle (MCNP) simulated data and the analytical data. Good agreement between MCNP and analytical values has been found. Indeed, the beam-hardening effect is well supported in the proposed method. A correction procedure is developed to correct the errors of beam-hardening effect in neutron transmission, and therefore for projection data correction. The effectiveness of this procedure is determined by its application in correcting reconstructed images.

[Predictive factors of organ failure in patients admitted in intensive care unit for acute gastrointestinal bleeding]

INTRODUCTION

Gastrointestinal hemorrhage is an emergency requiring usually an admission in intensive care unit (ICU), which may prove abusive secondarily. The aim of this study was to identify predictive risk factors of organ failure in patients admitted for GH in our ICU.

DESIGN

Retrospective and observational

METHODS AND MEASUREMENTS

Between January 2008 and December 2011, all patients admitted in our ICU for gastrointestinal hemorrhage were consecutively included. The primary endpoint was the occurrence of at least an organ failure. We realized an univariate analysis then a backward regression to identify independent risk factors associated with the occurrence of at least one organ failure during the ICU hospitalization.

RESULTS

During this period study, 441 consecutive patients with a mean age of 67±15years were included. The median ICU length of stay was of 4 (3-7) days and 116 (26% [IC95%: 22-30]) patients presented at least one organ failure. The multivariate analysis identified predictive risk factors of organ failure: history of cirrhosis (OR=3.5 [IC95%: 1.9-6.7], P<0.001) and an increase in troponin at the admission above the 99th percentile (OR=3.1 [IC95%: 1.8-5.5], P<0.001).

CONCLUSION

Our results confirmed that a large proportion of patients admitted in ICU for the primary diagnosis of gastrointestinal hemorrhage developed any organ failure. The history of cirrhosis and the systemic consequences of the hemorrhagic syndrome as myocardial damage represents important risk factors of morbidity and mortality and thus should be considered during the management.