Dietmar Krausch

Monocyte deactivation : rationale for a new therapeutic strategy in sepsis

Inflammatory cells, in particular monocytes/macrophages, release pro-inflammatory mediators in response to several infectious and non-infectious stimuli. The excessive release of these mediators, resulting in the development of whole body inflammation, may play an important role in the pathogenesis of sepsis and septic shock. TNF-alpha, acting synergistically with cytokines such as IL-1, GM-CSF and IFN-gamma, is the key mediator in the induction process of septic shock, as shown in several experimental models. Based on this concept and on the encouraging results obtained in several experimental models, a number of clinical sepsis trials targeting the production or action of TNF-alpha or IL-1 have been performed in recent years. Unfortunately, these trials have failed to demonstrate a therapeutic benefit. One reason for this may be the lack of exact immunologic analyses during the course of septic disease. Recently, we demonstrated that there is a biphasic immunologic response in sepsis: an initial hyperinflammatory phase is followed by a hypo-inflammmatory one. The latter is associated with immunodeficiency which is characterized by monocytic deactivation, which we have called “immunoparalysis”. While anti-inflammatory therapy (e.g. anti-TNF antibodies, IL-1 receptor antagonist, IL-10) makes sense during the initial hyperinflammatory phase, immune stimulation by removing inhibitory factors (plasmapheresis) or the administration of monocyte activating cytokines (IFN-gamma, GM-CSF) may be more useful during “immunoparalysis”.

Metabolic Complications during Regional Citrate Anticoagulation in Continuous Venovenous Hemodialysis: Single-Center Experience

Background: Regional anticoagulation with trisodium citrate is an effective form of anticoagulation for continuous renal replacement therapy (CRRT) in patients at a high risk of bleeding. In a prospective, observational study we compared an established regional citrate anticoagulation protocol [Mehta R et al: Kidney Int 1990;38:976–981] versus a standard heparin anticoagulation protocol focusing on acid-base and electrolyte derangements as well as on cost effectiveness. Methods and Results: 209 patients were included in the study. In 37 patients, citrate was used as the sole anticoagulant, 87 patients received low-dose heparin plus citrate, and 85 patients received only heparin as anticoagulant. A customized dialysate solution was used for citrate-anticoagulated CRRT (no buffer, no calcium, reduced sodium concentration). Filter life was significantly higher during citrate anticoagulation compared to heparin anticoagulation (80.2 ± 60 vs. 30.2 ± 32 h; p < 0.001). No difference was found between citrate and citrate-heparin anticoagulation (p = 0.310). Metabolic alkalosis was observed in more than 50% of patients on citrate anticoagulation. Alkalosis developed within the first 72 h after initiating treatment and could be reversed in almost all cases by increasing the dialysate flow rate. Hypercalcemia was observed in 13 patients on citrate anticoagulation. Patients with impaired liver function were particularly at risk. Systemic hypocalcemia, hypernatremia, and anion gap acidosis were not observed. Citrate anticoagulation was well tolerated hemodynamically. A longer filter life during citrate anticoagulation translated into a significant cost reduction compared to standard heparin anticoagulation (p < 0.01). Conclusion: Regional anticoagulation with trisodium citrate in combination with a customized calcium-free dialysate is a safe and effective alternative to a heparin-based anticoagulation regimen.

Regional Citrate Anticoagulation in Continuous Hemodialysis – Acid-Base and Electrolyte Balance at an Increased Dose of Dialysis

Background: Citrate anticoagulation is an excellent alternative to heparin anticoagulation for patients at high risk of bleeding requiring continuous renal replacement therapy. However, citrate anticoagulation has some potential adverse effects such as metabolic alkalosis and acidosis, hypernatremia, hypo- and hypercalcemia. Thus, most citrate anticoagulation protocols use specially designed dialysis fluids to compensate for most of these disarrangements. This study aimed at establishing a citrate anticoagulation protocol designed for a dialysate flow rate of about 2 l/h. Methods: Based on theoretical considerations we composed a dialysis fluid suitable for a 2 l/h dialysis flow rate. The dialysate contained 133 mmol/l sodium, 2 mmol/l potassium, 1.1 mmol/l magnesium, 25 mmol/l lactate, and 112.2 mmol/l chloride. Results: Twenty-three patients were included in the study. During the treatments minor flow rate adaptations were needed and the treatments were well tolerated. Filter life was appropriate (51.3 ± 24.6 h). Thirteen patients developed a mild metabolic alkalosis (pH > 7.45 plus BE > +3) which was easily counteracted by increasing the dialysis fluid flow (by increments of 500 ml). Acid-base values returned to normal within 24 h after increasing the dialysate flow. The maximum dialysate flow was 3,000 ml/h. Hypernatremia and hypocalcemia were not observed. The systemic ionized calcium concentration was successfully controlled by adjustments of a continuous calcium infusion made with respect to the results of 6-hourly measurements. Conclusion: The analyzed citrate anticoagulation protocol was well tolerated and filter lifetime was appropriate. Regional anticoagulation with trisodium citrate in combination with a customized calcium-free dialysate is a safe and effective alternative to a heparin-based anticoagulation regimen.

Intermittent High-Permeability Hemofiltration Modulates Inflammatory Response in Septic Patients with Multiorgan Failure

Background/Aim: Continuous venovenous hemofiltration with high-permeability hemofilters is a novel approach in the adjuvant therapy of septic patients. High-permeability hemofilters are characterized by an increased pore size which facilitates the filtration of inflammatory mediators. The present study examines whether intermittent high-permeability hemofiltration has an immunomodulatory effect on polymorphonuclear leukocytes and mononuclear cells. Methods: Twenty-eight septic patients with acute renal failure were randomly allocated to either receive intermittent high-permeability or conventional hemofiltration. Intermittent high-permeability hemofiltration consisted of a daily 12-hour course of high-permeability hemofiltration alternated by conventional hemofiltration. For high-permeability hemofiltration, a newly developed high-flux polyamide membrane (P2SH) with a nominal cutoff point of 60 kD was used. For conventional hemofiltration a high-flux polyamide hemofilter (Polyflux 11S, cutoff point 30 kD) was used. Results: The polymorphonuclear leukocyte phagocytosis activity before starting hemofiltration was almost double the rate of healthy controls in both groups (p < 0.001). The phagocytosis rate decreased significantly during the course of intermittent high-permeability hemofiltration (p < 0.05), whereas the values remained unchanged in the conventional hemofiltration group. Incubation of high-permeability filtrates with blood from healthy donors resulted in a significant induction of phagocytosis (p < 0.001), whereas conventional filtrates had no phagocytosis-stimulating effects. In addition, incubation of healthy-donor mononuclear cells with high-permeability but not conventional filtrates resulted in a significant tumor necrosis factor alpha release (p < 0.001). Conclusions: Intermittent high-permeability hemofiltration is a novel extracorporeal elimination modality which exhibits immunomodulatory effects on leukocytes, attenuating polymorphonuclear neutrophil phagocytosis. Further studies are necessary to elucidate whether these effects translate in a clinical improvement in patients suffering from sepsis.

Acute intravascular hemolysis after transfusion of a chimeric RBC unit

BACKGROUND:  Natural blood cell chimerism rarely occurs in humans. The case of a patient who developed transfusion reaction due to the transfusion of chimeric RBCs is reported.

Einfluß einer Selensubstitution auf verschiedene Laborparameter bei sepsisgefährdeten Patienten

Summary□Background: Low selenium plasma levels were often measured in ICU patients with polytrauma, major surgery or various severe diseases. Activation of selenium-dependent functions of the antioxidant metabolism and the immune system is suggested to be causally.□Methods: In a prospective randomized clinical trial including 24 critically ill patients we investigated the plasma levels of selenium, malondialdehyde, glutathione, elastase, fT3, fT4, TSH, IL-2R, IL-6 and IL-8 with and without parenteral selenium supplementation for 3 weeks (study design: week 1: twice 500 µg daily, week 2: once 500 µg, week 3: three times 100 µg sodium selenite).□Results: Following 24 hours of supplementation selenium plasma levels were normalized. Malondialdehyde level decreased in the therapy group significantly beginning at day 3. In the control group we observed increased malondialdehyde values, a disturbed glutathione metabolism and an elevated elastase activity. fT3-values were diminished at day 0 in all patients. In the therapy group we measured a gradual fT3 restoration. In the control group a reactive TSH increase was observed. Selenium supplementation did not lead to an excessive stimulation of IL-2R, IL-6 or IL-8.□Conclusions: 1. Rapid normalization of selenium plasma levels can be achieved with the applied selenium dosage. 2. Parameters of radical metabolism are significantly reduced following selenium administration. 3. T3 synthesis correlates closely with the selenium levels. 4. Excessive stimulation of the immune system does not appear in the applied dosage.BACKGROUND Low selenium plasma levels were often measured in ICU patients with polytrauma, major surgery or various severe diseases. Activation of selenium-dependent functions of the antioxidant metabolism and the immune system is suggested to be causally. METHODS In a prospective randomized clinical trial including 24 critically ill patients we investigated the plasma levels of selenium, malondialdehyde, glutathione, elastase, fT3, fT4, TSH, IL-2R, IL-6 and IL-8 with and without parenteral selenium supplementation for 3 weeks (study design: week 1: twice 500 micrograms daily, week 2: once 500 micrograms, week 3: three times 100 micrograms sodium selenite). RESULTS Following 24 hours of supplementation selenium plasma levels were normalized. Malondialdehyde level decreased in the therapy group significantly beginning at day 3. In the control group we observed increased malondialdehyde values, a disturbed glutathione metabolism and an elevated elastase activity. fT3-values were diminished at day 0 in all patients. In the therapy group we measured a gradual fT3 restoration. In the control group a reactive TSH increase was observed. Selenium supplementation did not lead to an excessive stimulation of IL-2R, IL-6 or IL-8. CONCLUSIONS 1. Rapid normalization of selenium plasma levels can be achieved with the applied selenium dosage. 2. Parameters of radical metabolism are significantly reduced following selenium administration. 3. T3 synthesis correlates closely with the selenium levels. 4. Excessive stimulation of the immune system does not appear in the applied dosage.