Liver transplant with controlled donors after circulatory death with normothermic regional perfusion and brain dead donors: A multicenter cohort study of transfusion, one-year graft survival and mortality

BACKGROUND

Controlled donation after circulatory death (cDCD) has expanded the donor pool for liver transplantation (LT). However, transfusion requirements and perioperative outcomes should be elucidated. The aim of this multicenter study was to assess red blood cell (RBC) transfusions, one-year graft and patient survival after LT after cDCD with normothermic regional perfusion (NRP) compared with donors after brain death (DBD).

METHODS

591 LT carried out in ten centers during 2019 were reviewed. Thromboelastometry was used to manage coagulation and blood product transfusion in all centers. Normothermic regional perfusion was the standard technique for organ recovery.

RESULTS

447 patients received DBD and 144 cDCD with NRP. Baseline MCF Extem was lower in the cDCD group There were no differences in the percentage of patients (63% vs. 61% p = 0.69), nor in the number of RBC units transfused (4.7 (0.2) vs 5.5 (0.4) in DBD vs cDCD, p = 0.11. Twenty-six patients (6%) died during admission for LT in the DBD group compared with 3 patients (2%) in the cDCD group (p = 0.15). To overcome the bias due to a worse coagulation profile in cDCD recipients, matched samples were compared. No differences in baseline laboratory data, or in intraoperative use of RBC or one-year outcome data were observed between DBD and cDCD recipients.

CONCLUSIONS

cDCD with NRP is not associated with increased RBC transfusion. No differences in graft and patient survival between cDCD and DBD were found. Donors after controlled circulatory death with NRP can increasingly be utilized with safety, improving the imbalance between organ donors and the ever-growing demand.

Baseline haemoglobin and thromboelastometry are predictive of red blood cell requirements and one-year mortality in liver transplantation

BACKGROUND

To determine the predictive capacity of baseline haemoglobin and maxim clot firmness (MCF) EXTEM thromboelastometry for intraoperative red blood cell (RBC) requirements and its influence on mortality.

METHODS

591 adult liver transplant (LT) recipients from ten Spanish centres were reviewed. The main outcomes were the percentage of patients who received RBC and massive transfusion (≥ 6 RBC units), RBC units transfused, and mortality.

RESULTS

76 % received a donor after brain death graft and 24 % a controlled donor after circulatory death graft. Median (interquartile ranges) RBC transfusion was 2 (0-4) units, and 63 % of patients were transfused. Comparing transfused and non-transfused patients, mean (standard deviation) for baseline haemoglobin was 10.4 (2.1) vs. 13.0 (1.9) g/dl (p = 0.001), EXTEM MCF was 51(11) vs. 55(9) mm (p = 0.001). Haemoglobin and EXTEM MCF were inversely associated with the need of transfusion odds ratio (OR) of 0.558 (95 % CI 0.497-0.627, p < 0.001) and OR 0.966 (95 % CI0.945-0.987, p = 0.002), respectively. Pre-operative baseline haemoglobin ≤ 10 g/dL predicted RBC transfusion, sensitivity of 93 % and specificity of 47 %. Massive transfusion (MT) was received by 19 % of patients. Haemoglobin ≤10 g/dL predicted MT with sensitivity 73 % and specificity of 52 %. One-year patient and graft survival were significantly lower in patients who required MT (78 % and 76 %, respectively) vs. those who did not (94 % and 93 %, respectively).

DISCUSSION

whereas EXTEM MCF is less dreterminant predicting RBC requirements, efforts are required to improve preoperative haemoglobin up to 10 g/dl in patients awaiting LT.

Assessing the effect of conformational averaging on the measured values of observables

Experiment and computer simulation are two complementary tools to understand the dynamics and behavior of biopolymers in solution. One particular area of interest is the ensemble of conformations populated by a particular molecule in solution. For example, what fraction of a protein sample exists in its folded conformation? How often does a particular peptide form an alpha helix versus a beta hairpin? To address these questions, it is important to determine the sensitivity of a particular experiment to changes in the distribution of molecular conformations. Consequently, a general analytic formalism is proposed to determine the sensitivity of a spectroscopic observable to the underlying distribution of conformations. A particular strength of the approach is that it provides an expression for a weighted average across conformational substates that is independent of the averaging function used. The formalism is described and applied to experimental and simulated nuclear Overhauser enhancement (NOE) and 3J-coupling data on peptides in solution.

Prediction of the binding free energies of new TIBO-like HIV-1 reverse transcriptase inhibitors using a combination of PROFEC, PB/SA, CMC/MD, and free energy calculations

We have ranked 13 different TIBO derivatives with respect to their relative free energies of binding using two approximate computational methods: adaptive chemical Monte Carlo/molecular dynamics (CMC/MD) and Poisson-Boltzmann/solvent accessibility (PB/SA) calculations. Eight of these derivatives have experimentally determined binding affinities. The remaining new derivatives were constructed based on contour maps around R86183 (8Cl-TIBO), generated with the program PROFEC (pictorial representation of free energy changes). The rank order among the derivatives with known binding affinity was in good agreement with experimental results for both methods, with average errors in the binding free energies of 1. 0 kcal/mol for CMC/MD and 1.3 kcal/mol for the PB/SA method. With both methods, we found that one of the new derivatives was predicted to bind 1-2 kcal/mol better than R86183, which is the hitherto most tightly binding derivative. This result was subsequently supported by the most rigorous free energy computational methods: free energy perturbation (FEP) and thermodynamic integration (TI). The strategy we have used here should be generally useful in structure-based drug optimization. An initial ligand is derivatized based on PROFEC suggestions, and the derivatives are ranked with CMC/MD and PB/SA to identify promising compounds. Since these two methods rely on different sets of approximations, they serve as a good complement to each other. Predictions of the improved affinity can be reinforced with FEP or TI and the best compounds synthesized and tested. Such a computational strategy would allow many different derivatives to be tested in a reasonable time, focusing synthetic efforts on the most promising modifications.

Graphical visualization of mean hydration from molecular dynamics simulations

How does one characterize water solvating a complex solute? Specific hydration of proteins and nucleic acids plays a key role in many biological processes. However, traditional pairwise descriptions of solvent structure (radial distribution functions, etc.) are incapable of adequately describing the hydration of these complex solutes. We have developed methods to visualize the average three-dimensional water structure surrounding a solute, as seen in a molecular dynamics (MD) simulation. Applications to simple solutes [sodium ion, N-methyl acetamide, 18-crown-6, (hydroxymethyl)phenols] are presented, and the extension of the method to larger molecules of biochemical interest is discussed.