Sven Laudi

Chronic renal dysfunction following liver transplantation

Abstract:  With most of the immunosuppressive protocols consisting of calcineurin inhibitors (CI), nephrotoxicity has become a major long‐term complication often compromising outcome. In a single‐center retrospective study, we reviewed 1173 liver transplantations to identify variables indicative for the occurrence of chronic renal dysfunction (CRD) (defined as ≥1 episode of serum creatinine increase ≥1.8 mg/dL ≥2 wk). Chronic renal dysfunction was found in 137 (11.7%) of all transplants [82 (7%) early (after 3–12 months), 55 (4.7%) late‐onset (>12 months)]. Compared to 5‐/10‐yr survival rates in non‐CRD transplants (84/74%) survival was significantly decreased in early (66/46%), but unchanged in late‐onset CRD (98/86%). Rates of alcoholic cirrhosis and prior renal dysfunction were significantly increased in patients with CRD. In a multivariate logistic regression analysis, only cyclosporine A (CyA) as immunosuppression remained an independent risk factor. No correlations to age, gender, rejection/retransplantation or diabetes were found. Surprisingly, renal function (creatinine) showed no difference between patients on CI monotherapy (FK/CyA) compared to those who had mycophenolate mofetil (MMF) added. In liver transplantation, early onset CRD significantly compromises survival. CyA‐based immunosuppression appears to have a stronger impact than FK. The fact that patients with long‐term severe chronic renal dysfunction failed to improve under MMF rescue therapy emphasizes the importance of new diagnostic strategies to earlier identify at‐risk patients.

Impact of the MELD allocation after its implementation in liver transplantation

Abstract Objective . On 16 December 2006, most Eurotransplant countries changed waiting time oriented liver allocation policy to the urgency oriented Model for End-stage Liver Disease (MELD) system. There are limited data on the effects of this policy change within the Eurotransplant community. Patients and methods. A total of 154 patients who had undergone deceased donor liver transplantation (LT) were retrospectively analyzed in three time periods: period A (1-year pre-MELD, n = 42) versus period B (1-year post-MELD, n = 52) versus period C (2 years after MELD implementation, n = 60). Results. The median MELD score at the time of LT increased from 16.3 points in period A to 22.4 and 20.4 in periods B and C, respectively (p = 0.007). Waitlist mortality decreased from 18.4% in period A to 10.4% and 9.4% in periods B and C, respectively (p = 0.015). Three-month mortality did not change significantly (10% each for periods A, B and C). One-year survival was 84% for the MELD 6–19 group compared with 81% in the MELD 20–29 group and 74% in the MELD ≥30 group (p = 0.823). Analyzing MELD score and previously described prognostic scores [i.e. survival after liver transplantation (SALT) score and donor-MELD (D-MELD) score] with regard to 1-year survival, only a high risk SALT score was predictive (p = 0.038). In our center, 2 years after implementation of the MELD system, waitlist mortality decreased, while 90-day mortality did not change significantly. Conclusion. Up to now, only the SALT score proved to be of prognostic relevance post-transplant.

MURINE PULMONARY RESPONSE TO CHRONIC HYPOXIA IS STRAIN SPECIFIC

Information concerning the effects of genetic variation between different background strains on hemodynamic, morphometric, and gene expression response to hypoxia would be useful. Three strains of mice were kept in hypoxia and phenotyped followed by gene profiling analysis. Among the variables examined, hematocrit, right heart muscularization, and right ventricular systolic pressure showed a strain-specific effect. Increased gene expression of inflammatory, muscle, and angiogenesis genes were seen in all strains, though the specific genes changed varied among groups. These results suggest that different strains use different gene expression mechanisms to adapt to the challenge of chronic hypoxia, resulting in modified phenotypic changes.

Impact of organ preservation using HTK for graft flush and subsequent storage in UW in rat kidney transplantation.

Background: In kidney transplantation, preservation has a significant influence on organ function. Since previous reports have indicated a benefit of combining histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) solution, we evaluated the effects of initial flush with low viscosity HTK, followed by storage in UW. Material and Methods: Kidneys from inbred Lewis rats were procured using HTK or UW for initially perfusion and re-flushed after 30 min with either solution. In a third group, after perfusion with HTK, organs were re-flushed with UW. Organs were stored for 16–24 h (4°C). Study parameters were high-energy phosphates, histology, apoptosis, recipient survival and urine excretion of 15-F2t-isoprostanes (oxidative stress marker). Results:Prior to transplantation, tissue ATP/ADP concentrations were: HTK/UW>UW-only >HTK-only. In transplanted kidneys, histological damage was highest after preservation in HTK-only. Twenty-four hours after transplantation (24 h cold ischemia time – CIT), cleaved-PARP was most abundant using UW-only. 16 h of CIT resulted in higher urine concentrations of isoprostanes in the order HTK-only (368 ± 308) > UW-only (157 ± 105) > HTK/UW (67 ± 26), and was lower in HTK/UW after 24 h of CIT (146 ± 38) vs. UW-only (507 ± 33 pg/mg creatinine). Survival (24 h CIT) was significantly reduced, and percentage of initial non-functioning (INF) kidneys highest in HTK-only (2.6 ± 0.3 days, 100%), compared to UW-only (13 ± 4.4 days, 75%) and HTK/UW (18.5 ± 4.6 days, 33%). Conclusions: In long-term preservation, UW is superior over HTK. However, our results indicate that perfusion with HTK prior to storage in UW may improve the results of UW alone which is reflected by better survival, lower rate of INF, higher cellular energy conservation and a decrease of free radicals.

Characterization of a double-hit murine model of acute respiratory distress syndrome

The aim of the present study was to characterize a murine model of acute respiratory distress syndrome (ARDS) abiding by the Berlin definition of human ARDS and guidelines for animal models of ARDS. To this end, C57BL/6NCrl mice were challenged with lipopolysaccharide (LPS; 15 mg/kg, i.p.) followed 18 h later by injection of oleic acid (OA; 0.12 mL/kg, i.v.). Controls received saline injection at both time points. Haemodynamics were monitored continuously. Arterial blood gas analyses were performed just before and every 30 min after OA challenge. Ninety minutes after OA challenge, the chest of mice was scanned using micro‐computed tomography (CT). Cytokine concentrations were measured in plasma samples. Lungs were harvested 90 min after OA challenge for histology, immunohistochemistry, lung weight measurements and tissue cytokine detection. A histological lung injury score was determined. Eighteen hours after LPS challenge, mice exhibited a severe systemic inflammatory response syndrome. Oxygenation declined significantly after OA injections (Pao2/Fio2 283 ± 73 and 256 ± 71 mmHg at 60 and 90 min, respectively; P < 0.001). Bilateral patchy infiltrates were present on the micro‐CT scans. Histology revealed parenchymal damage with accumulation of polymorphonuclear neutrophils, intra‐alveolar proteinacous debris and few hyaline membranes. The lung wet : dry ratio indicated damage to the alveolar capillary membrane. Cytokine patterns evidenced a severe local and systemic inflammatory state in plasma and lung tissue. In conclusion, the described two‐hit model of ARDS shows a pathological picture of ARDS closely mimicking human ARDS according to the Berlin definition and may facilitate interpretation of prospective experimental results.

Inhaliertes Stickstoffmonoxid zur Behandlung refraktärer Hypoxämie bei ARDS–Patienten

The acute respiratory distress syndrome (ARDS) is characterized by a maldistribution of pulmonary blood flow towards non-ventilated atelectatic lung areas being the main reason for intrapulmonary right-to-left shunt with the consequence of severe arterial hypoxemia. The application of inhaled nitric oxide (iNO) is a therapeutic option to selectively influence pulmonary blood flow in order to improve arterial oxygenation and to decrease pulmonary artery pressure without relevant systemic side effects. Although randomized controlled trials demonstrated no survival benefit in patient populations covering the entire severity range of acute lung injury, iNO represents a feasible rescue treatment for ARDS patients with severe refractory hypoxemia and is, therefore, an important option for ARDS therapy in specialized centers.

Endothelin-1 influences the efficacy of inhaled nitric oxide in experimental acute lung injury.

Beneficial effects of inhaled nitric oxide (iNO) on arterial oxygenation in acute lung injury (ALI) suggest the presence of vasoconstriction in ventilated lung regions and this may be influenced by endothelin-1 (ET-1). We studied a possible interaction between ET-1 and iNO in experimental ALI. Sixteen piglets were anesthetized and mechanically ventilated (inspired O2 fraction, 1.0). After induction of ALI by surfactant depletion, animals were randomly assigned to either inhale 30 ppm NO (iNO group, n=8), or to receive no further intervention (controls, n=8). Measurements were performed during the following 4 hrs. In all animals, induction of ALI significantly decreased arterial oxygen tension (PaO2) from 569 ± 15 (prelavage) to 58 ± 3 mm Hg. Inhaled NO significantly increased PaO2 when compared with controls (iNO group: 265 ± 51 mm Hg; controls: 50 ± 4 mm Hg, values at 4 hrs, P < 0.01). Prelavage ET-1 plasma levels were comparable between groups (iNO: 0.74 ± 0.03, controls: 0.71 ± 0.03 fmol/ml, NS). During the protocol, the ET-1 levels increased and were different at 3 hrs (iNO: 0.93 ± 0.06, controls: 1.25 ± 0.09 fmol/ml; P < 0.05). PaO2 changes induced by iNO revealed a moderate and significant correlation with ET-1 plasma levels (R = 0.548, P = 0.001). Our data suggest that endogenous ET-1 production influences the efficacy of iNO in ALI. Furthermore, iNO reduced ET-1 plasma levels, possibly indicating anti-inflammatory properties of iNO in the early phase of ALI.

Interhospitaltransport von Patienten mit ARDS

ZusammenfassungDie Therapie von Patienten mit schwerer Gasaustauschstörung ist technisch und personell aufwendig und sollte in spezialisierten Zentren durchgeführt werden. Daher sollte ein zeitnaher Transport in ein solches Zentrum angestrebt werden. Wird der Transport durch ein erfahrenes Transportteam durchgeführt, überwiegen die Vorteile der dadurch gewährleisteten spezifischen Therapie deutlich gegenüber den Transportrisiken. Hierbei müssen jedoch die Wahl des Transportmittels, das Equipment und das Personal sorgfältig geplant werden. Patienten- und transportassoziierte Risiken müssen berücksichtigt und eine adäquate Konditionierung des Patienten vor Transportbeginn zur Abwendung drohender Komplikationen durchgeführt werden. Dieser Beitrag soll eine Übersicht geben, über patientenseitige Aspekte, verschiedene Transportformen und assoziierte Risiken. Zudem wird der optimale Ablauf eines Patiententransports, beginnend mit dem Erstkontakt der verlegenden Klinik bis zur praktischen Durchführung, erläutert.AbstractIn patients with severely compromised gas exchange, interhospital transportation is frequently necessary due to the need to provide access to specialized care. Risks are inherent during transport, so the anticipated benefits of transportation must be weighed against the possible negative outcome during the transport. The use of specialized teams during transportation can help to reduce adverse events. Diligent planning of the transportation, monitoring and medical staff during transport can decrease adverse events and reduce risks. This article defines the group of patients that may benefit from referral. This article discusses the risks associated with the transportation of patients with severely impaired gas exchange and the risks related to different means of transportation. The decisions required before transportation are described as well as the practical approach starting at the transferring hospital until arrival at the admitting hospital.

The effects of hemoglobin glutamer-200 and iNO on pulmonary vascular tone and arterial oxygenation in an experimental acute respiratory distress syndrome

INTRODUCTION Hemoglobin-based oxygen carriers (HBOC) have been developed as an alternative to blood transfusions. Their nitric-oxide-scavenging properties HBOC also induce vasoconstriction. In acute lung injury, an excess of nitric oxide results in a general vasodilation, reducing oxygenation by impairing the hypoxic pulmonary vasoconstriction. Inhaled nitric oxide (iNO) is used to correct the ventilation perfusion mismatch. We hypothesized that the additional use of HBOC might increase this effect. In a rodent model of ARDS we evaluated the combined effect of HBOC and iNO on vascular tone and gas exchange. METHODS ARDS was induced in anaesthetized Wistar rats by saline lavage and aggressive ventilation. Two groups received either hydroxyethylstarch 10% (HES; n = 10) or the HBOC hemoglobin glutamer-200 (HBOC-200; n = 10) via a central venous infusion. Additionally, both groups received iNO. Monitoring of the right ventricular pressure (RVP) and mean arterial pressure (MAP) was performed with microtip transducers. Arterial oxygenation was measured via arterial blood gas analyses. RESULTS Application of HBOC-200 led to a significant increase of MAP and RVP when compared to baseline and to the HES group. This effect was reversed by iNO. The application of HBOC and iNO had no effect on the arterial oxygenation over time. No difference in arterial oxygenation was found between the groups. CONCLUSION Application of HBOC led to an increase of systemic and pulmonary vascular resistance in this animal model of ARDS. The increase in RVP was reversed by iNO. Pulmonary vasoconstriction by hemoglobin glutamer-200 in combination with iNO did not improve arterial oxygenation in ARDS.

Hydroxyethyl starch for volume expansion after subarachnoid haemorrhage and renal function: Results of a retrospective analysis

Background Hydroxyethyl starch (HES) was part of “triple-H” therapy for prophylaxis and therapy of vasospasm in patients with subarachnoid haemorrhage (SAH). The European Medicines Agency restricted the use of HES in 2013 due to an increase of renal failure in critically ill patients receiving HES compared to crystalloid fluids. The occurrence of renal insufficiency in patients with SAH due to HES is still uncertain. The purpose of our study was to evaluate whether there was an association with renal impairment in patients receiving HES after subarachnoid haemorrhage. Methods Medical records of all non-traumatic SAH patients treated at the Departments of Anaesthesiology and Neurosurgery, University Hospital of Leipzig, Germany, between January 2009 and December 2014 were analysed. Patients received either HES 6% and/or 10% (HES group, n = 183) or exclusively crystalloids for fluid therapy (Crystalloid group, n = 93). Primary outcome was the incidence of acute kidney injury. Results The study groups had similar characteristics except for initial SAPS scores, incidence of vasospasm and ICU length of stay. Patients receiving HES fulfilled significantly more often SIRS (systemic inflammatory response syndrome) criteria. 24.6% (45/183) of the patients in the HES group had acute kidney injury (KDIGO 1–3) at any time during their ICU stay compared to 26.9% (25/93) in the crystalloid group (p = 0.679). Only few patients needed renal replacement therapy with no significant difference between groups (Crystalloid group: 4.3%; HES group: 2.2%; p = 0.322). The incidence of vasospasm was increased in the HES group when compared to the crystalloid group (33.9% vs. 17.2%; p = 0.004). Conclusion In the presented series of patients with non-traumatic SAH we found no significant association between HES therapy and the incidence of acute kidney injury. Treatment without HES did not worsen patient outcome.