Intensivist-led management of brain-dead donors is associated with an increase in organ recovery for transplantation.

The disparity between the number of patients in need of organ transplantation and the number of available organs is steadily rising. We hypothesized that intensivist-led management of brain dead donors would increase the number of organs recovered for transplantation. We retrospectively analyzed data from all consented adult brain dead patients in the year before (n = 35) and after (n = 43) implementation of an intensivist-led donor management program. Donor characteristics before and after implementation were similar. After implementation of the organ donor support team, the overall number of organs recovered for transplantation increased significantly (66 out of 210 potentially available organs vs. 113 out of 258 potentially available organs, p = 0.008). This was largely due to an increase in the number of lungs (8 out of 70 potentially available lungs vs. 21 out of 86 potentially available lungs; p = 0.039) and kidneys (31 out of 70 potentially available kidneys vs. 52 out of 86 potentially available kidneys; p = 0.044) recovered for transplantation. The number of hearts and livers recovered for transplantation did not change significantly. Institution of an intensivist-led organ donor support team may be a new and viable strategy to increase the number of organs available for transplantations.

Volume management by renal replacement therapy in acute kidney injury.

Management of fluid balance is one of the basic but vital tasks in the care of critically ill patients. Hypovolemia results in a decrease in cardiac output and tissue perfusion and may lead to progressive multiple organ dysfunction, including the development of acute renal injury (AKI). However, in an effort to reverse pre-renal oliguria, it is not uncommon for patients with established oliguric acute renal failure, particularly when associated with sepsis, to receive excessive fluid resuscitation, leading to fluid overload. In patients with established oliguria, renal replacement therapy may be required to treat hypervolemia. Safe prescription of fluid loss during RRT requires intimate knowledge of the patient's underlying condition, understanding of the process of ultrafiltration and close monitoring of the patient's cardiovascular response to fluid removal. To preserve tissue perfusion in patients with AKI, it is important that RRT be prescribed in a way that optimizes fluid balance by removing fluid without compromising the effective circulating fluid volume. In patients who are clinically fluid overloaded, it is equally important that the amount of fluid removed be as exact as possible. Fluid balance errors can occur as a result of inappropriate prescription, operator error or machine error. Some CRRT machines have potential for significant fluid errors if alarms can be overridden. Threshold values for fluid balance error have been developed which can be used to predict the severity of harm. It is important that RRT education programs emphasize the risk associated with fluid balance errors and with overriding machine alarms.

[Interactions between lung and kidney in the critically ill]. / Lunge-Nieren-Interaktionen bei kritisch Kranken.

Interactions between lung and kidney can significantly affect the course of acute diseases, a phenomenon that was first observed in the 1950s by describing pulmonary dysfunction in uremic patients. From animal experiments there is ample evidence for remote lung injury following acute kidney injury (AKI), with an increased risk for the development of pulmonary edema and acute respiratory distress syndrome (ARDS). Coincident ARDS and AKI are associated with higher rates of intubation and mechanical ventilation, significantly prolonged weaning from mechanical ventilation and increased mortality. On the other hand, acute lung diseases and mechanical ventilation can promote the development of AKI and are associated with increased mortality when AKI is also present. These bidirectional interactions may include hemodynamic adverse effects during mechanical ventilation or volume overload as well as the release or decreased clearance and metabolism of proinflammatory mediators (e.g., interleukin-6 and tumor necrosis factor-α), which may induce and aggravate distant organ injury. The aim of this work is to examine the interactions between lung and the kidney in critically ill patients, as well as discuss potential preventive approaches.

Noninvasive ultrasound imaging of inflammation using microbubbles targeted to activated leukocytes.

BACKGROUND: Lipid microbubbles used for perfusion imaging with ultrasound are retained within inflamed tissue because of complement-mediated attachment to leukocytes within venules. We hypothesized that incorporation of phosphatidylserine (PS) into the microbubble shell may enhance these interactions by amplifying complement activation and thereby allow ultrasound imaging of inflammation. METHODS AND RESULTS: In 6 mice, intravital microscopy of tissue necrosis factor-alpha-treated cremaster muscle was performed to assess the microvascular behavior of fluorescein-labeled lipid microbubbles with and without PS in the shell. Ten minutes after intravenous injection, microbubble attachment to leukocytes within inflamed venules was greater for PS-containing than for standard lipid microbubbles (20+/-4 versus 10+/-3 per 20 optical fields, P<0.05). The ultrasound signal from retained microbubbles was assessed in the kidneys of 6 mice undergoing renal ischemia-reperfusion injury and in 6 control kidneys. The signal from retained microbubbles in control kidneys was low (<2.5 video intensity units) for both agents. After ischemia-reperfusion, the signal from retained microbubbles was 2-fold higher for PS-containing than for standard lipid microbubbles (18+/-6 versus 8+/-2 video intensity units, P<0.05). An excellent relation was found between the ultrasound signal from retained microbubbles and the degree of renal inflammation, assessed by tissue myeloperoxidase activity. CONCLUSIONS: -We conclude that noninvasive assessment of inflammation is possible by ultrasound imaging of microbubbles targeted to activated leukocytes by the presence of PS in the lipid shell.

Platelet, but not endothelial, P-selectin is critical for neutrophil-mediated acute postischemic renal failure.

In a neutrophil-dependent model of acute postischemic renal failure (APRF), eliminating or blocking P-selectin reduces postischemic neutrophil infiltration and preserves kidney function. This study was designed to identify the role of platelet vs. endothelial P-selectin in APRF. Using wild-type (wt) and P-selectin-deficient (P-/-) mice, we generated chimeric mice by bone marrow transplantation. Chimeric mice exclusively expressed either platelet (Plt-P) or endothelial P-selectin (EC-P). APRF was induced by bilateral renal ischemia in situ (32 min), followed by reperfusion; 48 h after reperfusion, EC-P had significantly lower creatinine concentrations (twofold over sham) than Plt-P (eightfold over sham). Compared with wt, protection from renal failure in EC-P was similar to that observed in P-/-. Plt-P and EC-P demonstrated similar overall postischemic neutrophil infiltration as measured by renal myeloperoxidase activity. However, Plt-P showed massive neutrophil infiltration into outer and inner medulla, similar to that in wt. EC-P had only patchy, more diffuse neutrophil influx. Our study identifies platelet P-selectin as crucial for postischemic neutrophil recruitment into outer and inner medulla, which is detrimental to the development of APRF. This suggests that novel therapeutic strategies for postischemic organ failure could be aimed at neutrophil-platelet interactions.

Evidence-based renal replacement therapy for acute kidney injury.

Acute kidney injury (AKI) with the subsequent need for renal replacement therapy (RRT) represents a persistent challenge, arising in 4-5% in critically-ill patients, and remains associated with a high mortality (60%) and morbidity. As AKI is an independent risk factor for poor prognosis, appropriate management of patients with AKI becomes of utmost importance. Complications of AKI can be treated with different forms of RRT, such as continuous veno-venous hemofiltration or intermittent hemodialysis. However, the timing of the initiation, the modality, and the dose of RRT are still controversial and the subject of ongoing clinical trials. This review presents and discusses currently available data regarding the use of RRT in critically-ill patients with AKI.

Protection from ischemia-reperfusion induced severe acute renal failure by blocking E-selectin.

OBJECTIVE: Despite progress in renal replacement therapy and critical care medicine, acute renal failure (ARF) still carries a very high mortality rate. Neutrophil infiltration has been recognized as a hallmark in postischemic renal injury. Neutrophil recruitment requires adhesion molecules including E-selectin, which mediates leukocyte rolling and adhesion. This study aims to identify the role of E-selectin in ischemia-reperfusion-induced severe ARF. DESIGN: Prospective, controlled, experimental study. SETTING: University animal research laboratory. SUBJECTS: C57BL/6 wild-type mice or C57BL/6 mice gene-deficient for E-selectin. INTERVENTIONS: Mice underwent 32-min bilateral renal ischemia or identical sham operations. After 4, 12, 24, or 48 hrs, kidneys were harvested and blood samples were taken. A separate group of wild-type mice received either antineutrophil serum or control serum 18 hrs before ischemia. Another group of wild-type mice was injected with function-blocking monoclonal E-selectin antibody or with control antibody 10 mins after reperfusion. Blood samples were taken 24 hrs later. MEASUREMENTS AND MAIN RESULTS: Blood creatinine and urea nitrogen concentrations, as well as renal myeloperoxidase activity indicating neutrophil infiltration, were measured. Reducing neutrophil counts by antineutrophil serum showed that in this model, organ failure strongly depends on neutrophil counts at time of ischemia. E-selectin deficient mice showed lower creatinine and blood urea nitrogen concentrations than wild-type mice at 24 and 48 hrs (a reduction of 60% to 80%). Kidneys of E-selectin deficient mice also revealed a lower myeloperoxidase activity maximum (75% reduction) at 24 hrs. Western blot analysis showed maximum E-selectin expression 24 hrs after ischemia-reperfusion. Immunostaining localized E-selectin to the endothelium of the peritubular capillary plexus. Compared with control antibody, postischemic injection of anti-E-selectin antibody gave lower creatinine concentrations at 24 hrs, similar to that seen in E-selectin deficient mice. CONCLUSIONS: In this model, blocking E-selectin even after onset of reperfusion protects from severe ARF, presumably by reducing postischemic neutrophil infiltration into the kidney. This suggests a new potential therapeutic perspective.

[Is there a means for cost reduction in intensive care fluid therapy without a loss of quality?]. / Ist eine Kostenreduktion in der Flüssigkeitstherapie bei Wahrung der Qualität in der Intensivtherapie möglich?

Cost reduction in fluid therapy may be possible without a loss in quality of medical therapy if the following principles are adhered to. 1: Compare the prices of different manufacturers. 2: The greater the product unit, the cheaper the milliliter. Adherence to this principle is limited by hygienic and logistic considerations. 3: 0.9% NaCl-solution is cheaper than Ringer's lactate-solution. Lactated Ringer's solution should be used, only, if there are contraindications against the higher solute concentrations and tonicity of 0.9% NaCl. 4: Crystalloids are cheaper than colloids. When choosing between these two options intravasal duration of action and specific adverse events must be considered. 5: Cost reduction by differential indication of artificial colloids. Comparing prices, one must consider risk of anaphylactoid/anaphylactic reactions, duration of action, limitation of dosage and possible hemostasis disorders. 6: Restrictive use of albumin. Albumin is the most expensive colloid. There are no reasons for routine use.

Altered membrane skeleton of hydroxyethylstarch-cryopreserved human erythrocytes.

Attempts have been made to use hydroxyethylstarch (HES) as an alternative to glycerol for cryopreservation of erythrocytes. However, HES cryopreservation causes significant transient rheological alterations in erythrocytes. Membrane proteins play a critical role for erythrocyte rheology. This study was undertaken to analyze erythrocyte membrane proteins during HES cryopreservation. Erythrocyte membranes with submembrane skeleton (ghosts) and the submembrane skeleton alone (unstripped skeletons) were prepared before freezing (native), after thawing and following 3 h reconditioning in glucose-enriched Ringer's solution (Ringer plus glucose), or in autologous fresh frozen plasma (AFFP). After electrophoresis protein concentrations (percentage of total protein) were determined by densitometry. In ghosts, no significant changes were found, whereas in unstripped skeletons the following results could be seen: beta-Spectrin: 31.8 +/- 2.2% (native), 22.1 +/- 0.8% (postthawing, P < 0.05 vs native), 22.4 +/- 1.6% (Ringer plus glucose, P < 0.05 vs native), 31.0 +/- 2.8% (AFFP). Other proteins remained unchanged. Since a significant decrease in beta-spectrin concentration after HES cryopreservation and after subsequent reconditioning in Ringer's solution with glucose was only detected in unstripped skeletons, this cannot be interpreted as in vivo protein loss. More likely, HES cryopreservation may have created changes in protein-protein associations. The course of beta-spectrin concentration parallels certain rheological and biochemical changes and might explain the transient rheological changes seen after HES cryopreservation.

Hypervolemic hemodilution: an alternative to acute normovolemic hemodilution? A mathematical analysis.

BACKGROUND: Hypervolemic hemodilution has been proposed as an alternative to normovolemic hemodilution to reduce homologous blood transfusions. So far, convincing data supporting this concept are unknown. MATERIALS AND METHODS: We therefore present a mathematical model calculating the efficacy of hypervolemic, normovolemic, and "no" hemodilution. Hypervolemic hemodilution constituted volume expansion (20% of estimated blood volume) maintained throughout surgery. Normovolemic hemodilution contained isovolemic exchange of blood (40% of estimated blood volume) vs colloid as well as retransfusing blood plus colloid to maintain minimal acceptable hematocrit, e.g., transfusion trigger. To determine the efficacy of each technique maximal allowable blood loss and final postoperative hematocrit were calculated. Maximal allowable blood loss referred to the amount of blood lost during surgery after which homologous blood transfusion became necessary. RESULTS: Recalculating published clinical data strongly validated the formulas used for our model. Hypervolemic hemodilution always revealed lowest maximal allowable blood losses. Normovolemic hemodilution constantly ensured highest maximal allowable blood losses. For blood losses <40% of blood volume, hypervolemic and normovolemic hemodilution provided almost identical final postoperative hematocrits. But in contrast to normovolemic hemodilution, hypervolemic hemodilution did not carry the risk of severe transient, retransfusion-induced hypervolemia. "No" hemodilution always gave lowest final postoperative hematocrits. CONCLUSIONS: Thus, hypervolemic hemodilution cannot replace normovolemic hemodilution to reduce homologous transfusions, but for blood losses <40% of blood volume hypervolemic hemodilution appears to be superior.

Blocking P-selectin protects from ischemia/reperfusion-induced acute renal failure.

Acute renal failure (ARF) in response to ischemia-reperfusion is thought to be associated with neutrophil infiltration. Neutrophil recruitment depends on adhesion molecules, including P-selectin. Our study sought to characterize the role of P-selectin in ischemia-reperfusion (I/R) -induced acute renal failure (ARF). In wild-type (wt) and P-selectin-deficient (P-/-) mice (both C57BL/6), ARF was induced by 32 min bilateral renal ischemia, followed by reperfusion (I/R). Wt showed a 12- and 20-fold increase in creatinine at 24 and 48 h after I/R, respectively. Similar changes were seen in blood urea nitrogen (BUN). By contrast, in P-/- creatinine and BUN increased only moderately (fourfold over sham). In wt, renal myeloperoxidase activity, indicating neutrophil infiltration, peaked after 24 h (19-fold over sham). This was significantly attenuated in P-/- (fivefold over sham). Western blot analysis revealed maximum P-selectin expression 12 h after I/R in wt. Immunostaining detected P-selectin in glomerular endothelium and in platelets adherent in glomerular and peritubular vessels. Postischemic injection of P-selectin antibody at 10 min after reperfusion, but not isotype control antibody, protected wt from ARF similar to the protection seen in P-/-. We conclude that blocking P-selectin even after onset of reperfusion protects mice from I/R-induced ARF, suggesting potential therapeutic strategies aimed at blocking P-selectin.

A CD2-green fluorescence protein-transgenic mouse reveals very late antigen-4-dependent CD8+ lymphocyte rolling in inflamed venules.

Intravital microscopy allows detailed analysis of leukocyte trafficking in vivo, but fails to identify the nature of leukocytes investigated. Here, we describe the development of a CD2-enhanced green fluorescence protein (EGFP)-transgenic mouse to characterize lymphocyte trafficking during inflammation in vivo. A CD2-EGFP plasmid construct including the CD2 promoter, the EGFP transgene, and the CD2 locus control region was injected into B6CBA/F1 pronuclei. EGFP+ offspring were backcrossed into C57BL/6 mice for six generations. Flow cytometry demonstrated that all peripheral blood EGFP+ cells were positive for CD2 and negative for the granulocyte Ag Ly 6-G (GR-1). EGFP(high) cells stained positive for CD2, CD3, CD8, TCR beta-chain, and NK1.1 but did not express the B cell and monocyte markers CD45RA, CD19, and CD11b. In vitro stimulation assays revealed no difference in lymphocyte proliferation and IL-2 secretion between EGFP+ and EGFP- mice. Intravital microscopy of untreated or TNF-alpha-treated cremaster muscle venules showed EGFP+ cells in vivo, but these cells did not roll or adhere to the vessel wall. In cremaster muscle venules treated with both TNF-alpha and IFN-gamma, EGFP(high) cells rolled, adhered, and transmigrated at a rolling velocity slightly higher (11 microm/s) than that of neutrophils (10 microm/s). Blocking alpha4 integrin with a mAb increased rolling velocity to 24 microm/s. These findings show that CD8+ T cells roll in TNF-alpha/IFN-gamma-pretreated vessels in vivo via an alpha4 integrin-dependent pathway.

Essential role of neutrophils in germ cell-specific apoptosis following ischemia/reperfusion injury of the mouse testis.

This study investigates the role of neutrophils in ischemia-induced aspermatogenesis in the mouse. Previous studies in the rat have demonstrated that ischemia-inducing testicular torsion followed by torsion repair and reperfusion resulted in germ cell-specific apoptosis. This was correlated with an increase in neutrophil adhesion to subtunical venules, an increase in reactive oxygen species, and increased expression of several apoptosis-associated molecules. In the present investigation, wild-type C57BL/6 mice were subjected to various degrees and duration of testicular torsion. A torsion of 720 degrees for 2 h caused disruption of the seminiferous epithelium and significantly reduced testis weight and daily sperm production. An immunohistochemical method specific for apoptotic nuclei indicated that these effects were due to germ cell-specific apoptosis. An increase in myeloperoxidase (MPO) activity and an increase in the number of neutrophils adhering to testicular subtunical venules after torsion repair/reperfusion demonstrated an increase in neutrophil recruitment to the testis. In contrast, E-selectin knockout mice and wild-type mice rendered neutropenic showed a significant decrease in neutrophil recruitment as evidenced by MPO activity and microscopic examination of subtunical venules. Importantly, germ cell-specific apoptosis was also reduced. Thus, germ cell-specific apoptosis is observed after ischemia/reperfusion of the murine testis, and this apoptosis is directly linked to the recruitment of neutrophils to subtunical venules. Endothelial cell adhesion molecules, particularly E-selectin, play an important role in mediating this pathology.