Dexmedetomidine pharmacokineticpharmacodynamic modelling in healthy volunteers:1. Influence of arousal on bispectral index and sedation

Background. Dexmedetomidine, a selective alpha(2)-adrenoreceptor agonist, has unique characteristics, such as maintained respiratory drive and production of arousable sedation. We describe development of a pharmacokinetic-pharmacodynamic model of the sedative properties of dexmedetomidine, taking into account the effect of stimulation on its sedative properties. Methods. In a two-period, randomized study in 18 healthy volunteers, dexmedetomidine was delivered in a step-up fashion by means of target-controlled infusion using the Dyck model. Volunteers were randomized to a session without background noise and a session with pre-recorded looped operating room background noise. Exploratory pharmacokineticpharmacodynamic modelling and covariate analysis were conducted in NONMEM using bispectral index (BIS) monitoring of processed EEG. Results. We found that both stimulation at the time of Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale scoring and the presence or absence of ambient noise had an effect on the sedative properties of dexmedetomidine. The stimuli associated with MOAA/S scoring increased the BIS of sedated volunteers because of a transient 170% increase in the effect-site concentration necessary to reach half of the maximal effect. In contrast, volunteers deprived of ambient noise were more resistant to dexmedetomidine and required, on average, 32% higher effect-site concentrations for the same effect as subjects who were exposed to background operating room noise. Conclusions. The new pharmacokinetic-pharmacodynamic models might be used for effect-site rather than plasma concentration target-controlled infusion for dexmedetomidine in clinical practice, thereby allowing tighter control over the desired level of sedation

Prolonged dual hypothermic oxygenated machine preservation (DHOPE-PRO) in liver transplantation:study protocol for a stage 2, prospective, dual-arm, safety and feasibility clinical trial

INTRODUCTION: End-ischaemic preservation of a donor liver by dual hypothermic oxygenated machine perfusion (DHOPE) for 2 hours prior to transplantation is sufficient to mitigate ischaemia-reperfusion damage and fully restore cellular energy levels. Clinical studies have shown beneficial outcomes after transplantation of liver grafts preserved by DHOPE compared with static cold storage. In addition to graft reconditioning, DHOPE may also be used to prolong preservation time, which could facilitate logistics for allocation and transplantation globally. METHODS AND ANALYSIS: This is a prospective, pseudo-randomised, dual-arm, IDEAL-D (Idea, Development, Exploration, Assessment, Long term study-Framework for Devices) stage 2 clinical device trial designed to determine safety and feasibility of prolonged DHOPE (DHOPE-PRO). The end-time of the donor hepatectomy will determine whether the graft will be assigned to the intervention (16:00–3:59 hour) or to the control arm (4:00–15:59 hour). In total, 36 livers will be included in the study. Livers in the intervention group (n=18) will undergo DHOPE-PRO (≥4 hours) until implantation the following morning, whereas livers in the control group (n=18) will undergo regular DHOPE (2 hours) prior to implantation. The primary endpoint of this study is a composite of the occurrence of all (serious) adverse events during DHOPE and up to 30 days after liver transplantation. ETHICS AND DISSEMINATION: The protocol was approved by the Medical Ethical Committee of Groningen, METc2020.126 in June 2020, and the study was registered in the Netherlands National Trial Registry (https://www.trialregister.nl/) prior to initiation. TRIAL REGISTRATION NUMBER: NL8740

Routine Postoperative Antithrombotic Therapy in Pediatric Liver Transplantation:Impact on Bleeding and Thrombotic Complications

BACKGROUND:  Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) are serious causes of morbidity and mortality after pediatric liver transplantation. To reduce thrombotic complications, routine antithrombotic therapy consisting of 1 week heparin followed by 3 months acetylsalicylic acid, was implemented in our pediatric liver transplant program in 2003. This study aimed to evaluate incidences of bleeding and thrombotic complications since the implementation of routine antithrombotic therapy and to identify risk factors for these complications. METHODS:  This retrospective cohort study includes 200 consecutive pediatric primary liver transplantations performed between 2003 and 2016. Uni- and multivariate logistic regression analysis, Kaplan-Meier method, and Cox regression analysis were used to evaluate recipient outcome. RESULTS:  HAT occurred in 15 (7.5%), PVT in 4 (2.0%), and venous outflow tract thrombosis in 2 (1.0%) recipients. Intraoperative vascular interventions (odds ratio [OR] 14.45 [95% confidence interval [CI] 3.75-55.67]), low recipient age (OR 0.81 [0.69-0.95]), and donor age (OR 0.96 [0.93-0.99]) were associated with posttransplant thrombosis. Clinically relevant bleeding occurred in 37%. Risk factors were high recipient age (OR 1.08 [1.02-1.15]), high Child-Pugh scores (OR 1.14 [1.02-1.28]), and intraoperative blood loss in mL/kg (OR 1.003 [1.001-1.006]). Both posttransplant thrombotic (hazard ratio [HR] 3.38 [1.36-8.45]; p = 0.009) and bleeding complications (HR 2.50 [1.19-5.24]; p = 0.015) significantly increased mortality. CONCLUSION:  In 200 consecutive pediatric liver transplant recipients receiving routine postoperative antithrombotic therapy, we report low incidences of posttransplant vascular complications. Posttransplant antithrombotic therapy seems to be a valuable strategy in pediatric liver transplantation. Identified risk factors for bleeding and thrombotic complications might facilitate a more personalized approach in antithrombotic therapy

Controlled DCD Liver Transplantation Is Not Associated With Increased Hyperfibrinolysis and Blood Loss After Graft Reperfusion

BACKGROUND: The specific effect of donation after circulatory death (DCD) liver grafts on fibrinolysis, blood loss, and transfusion requirements after graft reperfusion is not well known. The aim of this study was to determine whether transplantation of controlled DCD livers is associated with an elevated risk of hyper-fibrinolysis, increased blood loss and higher transfusion requirements upon graft reperfusion, compared to livers donated after brain death (DBD). METHODS: A retrospective single-center analysis of all adult recipients of a primary liver transplantation between 2000 and 2019 was performed (total cohort n= 628). Propensity score matching (PSM) was used to balance baseline characteristics for DCD and DBD liver recipients (PSM cohort n= 218). Intra- and postoperative hemostatic variables between DCD and DBD liver recipients were subsequently compared. Additionally, in vitro plasma analyses were performed to compare the intraoperative fibrinolytic state upon reperfusion. RESULTS: No significant differences in median (interquartile range) postreperfusion blood loss (1.2 L [0.5-2.2] vs 1.3 L (0.6-2.2); P= 0.62), RBC transfusion (2 units [0-4) vs 1.1 units [0-3], P= 0.21), or FFP transfusion requirements (0 units [0-2.2] vs 0 units (0-0.9); P= 0.11) were seen in DCD compared to DBD recipients, respectively. Furthermore, plasma fibrinolytic potential was similar in both groups. CONCLUSIONS: Transplantation of controlled DCD liver grafts does not result in higher intraoperative blood loss or more transfusion requirements, compared to DBD liver transplantation. In accordance to this, no evidence for increased hyper-fibrinolysis upon reperfusion in DCD compared to DBD liver grafts, was found

Sequential Hypothermic and Normothermic Machine Perfusion Enables Safe Transplantation of High-risk Donor Livers

Ex situ normothermic machine perfusion (NMP) is increasingly used for viability assessment of high-risk donor livers, whereas dual hypothermic oxygenated machine perfusion (DHOPE) reduces ischemia-reperfusion injury. We aimed to resuscitate and test the viability of initially-discarded, high-risk donor livers using sequential DHOPE and NMP with two different oxygen carriers: an artificial hemoglobin-based oxygen carrier (HBOC) or red blood cells (RBC). In a prospective observational cohort study of 54 livers that underwent DHOPE-NMP, the first 18 procedures were performed with a HBOC-based perfusion solution and the subsequent 36 procedures were performed with an RBC-based perfusion solution for the NMP phase. All but one livers were derived from extended criteria donation after circulatory death donors, with a median donor risk index of 2.84 (IQR 2.52-3.11). After functional assessment during NMP, 34 livers (63% utilization), met the viability criteria and were transplanted. One-year graft and patient survival were 94% and 100%, respectively. Post-transplant cholangiopathy occurred in 1 patient (3%). There were no significant differences in utilization rate and post-transplant outcomes between the HBOC and RBC group. Ex situ machine perfusion using sequential DHOPE-NMP for resuscitation and viability assessment of high-risk donor livers results in excellent transplant outcomes, irrespective of the oxygen carrier used

Déterrer, démêler et réarticuler les corps du génocide au Rwanda

This paper is concerned with the mass graves and exhumed bodies of victims of the Rwanda genocide and war of the 1990s. A government-led programme of exhumation of mass burials and individual graves has taken place over the last decade. The exhumation of mass graves has been undertaken, in the main, by Tutsi genocide survivors who work under the supervision of state officials. Post-unearthing, these bodies are unravelled, and the remnants of soft flesh, clothing, personal possessions and bones are separated from each other. Skeletal structures are fully disarticulated and the bones pooled into a vast collective, for placement within memorials. The outcome of these exhumations is that remains almost always lack individual identity at the point of reinterring. A productive analytical comparison is found in examining exhumations of Spanish Civil War graves, where the fates of individual dead are closely entangled with the lives of survivors. Here there is a clear contrast with exhumations in Rwanda, in the possible re-articulation of identities with specific human remains. But a similarity is also critical: in both cases the properties of human remains, as unsettling materials, garner specific 'affects', which drive forward national political projects that aim to consolidate particular collective memories of conflict, albeit that this kind of 'material agency' is mobilized to very different ends in each case

Best practices for managing large CryoEM facilities

Microscopic imaging and technolog