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Background.Selectivein-circuit blood cooling was recently shown to be an effective anticoagulation strategy during short-term haemofiltration. The aim of this study was to examine the safety of this novel method and circuit life. Methods. Fourteen pigs were randomly assigned to receive continuous haemofiltration with anticoagulation achieved either by selective cooling of an extracorporeal circuit (ECC) (COOL; n = 8) or through systemic heparinization (HEPARIN; n = 6). Before (T0) as well as 1 (TP1) and 6 h (TP6) after starting the procedure the following parameters were assessed: animal status, variables reflecting haemostasis, oxidative stress, inflammation and function of blood elements. Results. All animals remained haemodynamically stable with unchanged body core temperature and routine biochemistry. Regional ECC blood cooling did not alter clinically relevant markers of haemostasis, namely activated partial thromboplastin and prothrombin times, thrombin– antithrombin complexes, von Willebrand factor and plasminogen activator inhibitor-1. Platelet aggregability, serum levels offree haemoglobin, leukocyte count, oxidative burst and blastic transformation of T-lymphocytes were all found to be stable over the treatment period in both groups. ECC blood cooling affected neither plasma malondialdehyde concentrations (a surrogate marker of oxidative stress) nor plasma levels of cytokines (tumour necrosis factor-α, interleukin-6 and -10). While the patency of all circuits treated with systemic heparin was well maintained within the preselected period of 24 h, the median filter lifespan in the COOL group was 17 h. Conclusion. Utilizing clinically relevant markers, selective in-circuit blood cooling was demonstrated to be a safe and feasible means of achieving regional anticoagulation in healthy pigs. The long-term safety issues warrant further evaluation.

Critical illness, such as sepsis or septic shock with multiple organ dysfunction syndrome, is the leading cause of morbidity and mortality in intensive care units. The complexity of critical illness requires a robust methodology to explore the underlying mechanisms. Proteomics represents a powerful postgenomic biotechnology used for simultaneous examination of a large number of proteins or the proteome. Recent progress in proteomic techniques allows thorough evaluation of molecular changes associated with critical illness, thereby permitting to identify novel biomarkers and therapeutic targets. This review provides an update on the recent progress and potential of rapidly evolving proteomics approach to facilitate new discoveries in the field of critical care medicine.

Sepsis is a systemic response to infection commonly found in critically ill patients and is associated with multi-organ failure and high mortality rate. Its pathophysiology and molecular mechanisms are complicated and remain poorly understood. In the present study, we performed a proteomics investigation to characterize early host responses to sepsis as determined by an altered plasma proteome in a porcine model of peritonitis-induced sepsis, which simulated several clinical characteristics of human sepsis syndrome. Haemodynamics, oxygen exchange, inflammatory responses, oxidative and nitrosative stress, and other laboratory parameters were closely monitored. Plasma samples were obtained from seven pigs before and 12 h after the induction of sepsis, and plasma proteins were resolved with two-dimensional gel electrophoresis ( n =7 gels/group; before being compared with during sepsis). The resolved proteins were stained with the SYPRO Ruby fluorescence dye and subjected to quantitative and comparative analyses. From approx. 1500 protein spots visualized in each gel, levels of 36 protein spots were significantly altered in the plasma of animals with sepsis (sepsis/basal ratios or degrees of change ranged from 0.07 to 21.24). Q-TOF (quadrupole–time-of-flight) MS and MS/MS (tandem MS) identified 30 protein forms representing 22 unique proteins whose plasma levels were increased, whereas six forms of five unique proteins were significantly decreased during sepsis. The proteomic results could be related to the clinical features of this animal model, as most of these altered proteins have important roles in inflammatory responses and some of them play roles in oxidative and nitrosative stress. In conclusion, these findings may lead to a better understanding of the pathophysiology and molecular mechanisms underlying the sepsis syndrome. Abbreviations: 2-D, two-dimensional; ACN, acetonitrile; BP, blood pressure; CO, cardiac output; CVP, central venous pressure; DO2, oxygen delivery; DTT, dithiotheitol; FiO2, fraction of inspired oxygen; IEF, isoelectric focusing; IL, interleukin; LPS, lipopolysaccharide; Q-TOF, quadrupole–time-of-flight; MS/MS, tandem MS; NCBI, National Center for Biotechnology Information; NOx, nitrate/nitrite; PAOP, pulmonary artery occlusion pressure; PCO2, partial pressure of carbon dioxide; PEEP, positive end-expiratory pressure; PO2, partial pressure of oxygen; SVR, systemic vascular resistance; TBARS, thiobarbituric acid-reacting substances; TFA, trifluoroacetic acid; TNF-α, tumour necrosis factor-α; VO2, oxygen consumption

To test the hypothesis that cooling of blood in the extracorporeal circuit of continuous veno-venous hemofiltration (CVVH) enables to realize the procedure without the need of anticoagulation.Experimental animal study.We developed the device for selective cooling of extracorporeal circuit (20 degrees C) allowing blood rewarming (38 degrees C) just before returning into the body. Twelve anesthetized and ventilated pigs were randomized to receive either 6 h of CVVH with application of this device (COOL; n = 6) or without it (CONTR; n = 6).Before the procedure and in 15, 60, 180, 360 min after starting hemofiltration variables related to: (1) circuit patency [time to clotting (TC), number of alarm-triggered pump stopping (AS), venous and transmembranous circuit pressures (VP, TMP)], (2) coagulation status in the extracorporeal circuit [thrombin-antithrombin complexes (TAT(circ)), thromboelastography (TEG)] and (3) animal status (hemodynamics, hemolysis and biochemistry) were assessed.The patency of all circuits treated with selective cooling was well maintained within the observation period. By contrast, five of six sessions were prematurely clotted in the untreated group. As a result, the number of AS was significantly higher in the CONTR group. In-circuit thrombus generation in CONTR group was associated with a markedly increasing TAT(circ). TEG performed at 180 min of the procedure revealed a tendency to a prolonged initial clotting time and a significant decrease in clotting rate of in-circuit blood in the COOL group. No signs of repeated cooling/rewarming-induced hemolysis were observed in animals treated with "hypothermic circuit" CVVH.In this porcine model, regional extracorporeal blood cooling proved effective in preventing in-circuit clotting without the need to use any other anticoagulant.

Sepsis is the most common cause of acute kidney injury (AKI). There has been a growing body of evidence demonstrating the association between worsening of kidney function during sepsis and the risk of short- and long-term mortality. AKI in sepsis is associated with poor outcome and independently predicts increased mortality. Sepsis-associated AKI may therefore serve as a biomarker of adverse physiological events that portends worse outcome. Conversely, the important role of sepsis among intensive care unit patients with nonseptic AKI is increasingly being recognized. Indeed, sepsis represents a significant contributing factor to the overall mortality and incomplete recovery of kidney function in subjects who developed nonseptic AKI. Because AKI portends such an ominous prognosis in sepsis and vice versa, there has been a surge of interest in elucidating mechanisms underlying the complex and bidirectional nature of the interconnections between AKI, sepsis and multiorgan dysfunction. Accumulating data indicate that AKI can trigger several immune, metabolic and humoral pathways, thus potentially contributing to distant organ dysfunction and overall morbidity and mortality. The expanding population of patients with sepsis and AKI, and the associated excess mortality provide a strong basis for further research aimed at addressing more rigorously all potentially modifiable factors to reduce this burden to patients and health care systems. Better insights into bidirectional and synergistic pathways linking sepsis and AKI might open the window for new therapeutic approaches that interrupt this vicious circle. Here, we discuss the rationale for and the current understanding of the bidirectional relationship between AKI and sepsis.

The kidney is a common “victim organ” of various insults in critically ill patients. Sepsis and septic shock are the dominant causes of acute kidney injury, accounting for nearly 50 % of episodes of acute renal failure. Despite our substantial progress in the understanding of mechanisms involved in septic acute kidney injury there is still a huge pool of questions preclusive of the development of effective therapeutic strategies. This review briefly summarizes our current knowledge of pathophysiological mechanisms of septic acute kidney injury focusing on hemodynamic alterations, peritubular dysfunction, role of inflammatory mediators and nitric oxide, mitochondrial dysfunction and structural changes. Role of proteomics, new promising laboratory method, is mentioned.

The coupled plasma filtration adsorption (CPFA) was developed as an adsorptive hemopurification method aimed at nonselective removal of circulating soluble mediators potentially involved in the pathogenesis of sepsis. We hypothesized that this nonselective hemopurification could protect from detrimental consequences of long-term, volume-resuscitated porcine septic shock. In 16 anesthetized, mechanically ventilated, and instrumented pigs, the hyperdynamic septic shock secondary to peritonitis was induced by intraperitoneally inoculating feces and maintained for 22 h with fluid resuscitation and norepinephrine infusion as needed to maintain MAP above 65 mmHg. After 12 h of peritonitis, animals were randomized to receive either supportive treatment (control, n = 8) or CPFA treatment (CPFA, n = 8). Systemic, hepatosplanchnic, and renal hemodynamics; oxygen exchange; energy metabolism (lactate/pyruvate and ketone body ratios); ileal mucosal and renal cortex microcirculation; systemic inflammation (TNF-alpha, IL-6); nitrosative/oxidative stress (thiobarbituric acid reactive species, nitrates + nitrites); and endothelial/coagulation dysfunction (asymmetric dimethylarginine, von Willebrand factor, thrombin-antithrombin complexes, platelet count) were assessed before and 12, 18, and 22 h of peritonitis. Coupled plasma filtration adsorption neither delayed the development of hypotension nor reduced the dose of norepinephrine. The treatment failed to attenuate sepsis-induced alterations in microcirculation, surrogate markers of cellular energetics, endothelial injury, and systemic inflammation. Similarly, CPFA did not protect from lung and liver dysfunction and even aggravated sepsis-induced disturbances in coagulation and oxidative/nitrosative stress. In this porcine model of septic shock, the early treatment with CPFA was not capable of reversing the sepsis-induced disturbances in various biological pathways and organ systems. Both the efficacy and safety of this method require further rigorous experimental validation in clinically relevant models.

The role of haemofiltration as an adjunctive treatment of sepsis remains a contentious issue. To address the role of dose and to explore the biological effects of haemofiltration we compared the effects of standard and high-volume haemofiltration (HVHF) in a peritonitis-induced model of porcine septic shock. Randomized, controlled experimental study. Twenty-one anesthetized and mechanically ventilated pigs. After 12 h of hyperdynamic peritonitis, animals were randomized to receive either supportive treatment (Control, n = 7) or standard haemofiltration (HF 35 ml/kg per h, n = 7) or HVHF (100 ml/kg per hour, n = 7). Systemic and hepatosplanchnic haemodynamics, oxygen exchange, energy metabolism (lactate/pyruvate, ketone body ratios), ileal and renal cortex microcirculation and systemic inflammation (TNF-α, IL-6), nitrosative/oxidative stress (TBARS, nitrates, GSH/GSSG) and endothelial/coagulation dysfunction (von Willebrand factor, asymmetric dimethylarginine, platelet count) were assessed before, 12, 18, and 22 h of peritonitis. Although fewer haemofiltration-treated animals required noradrenaline support (86, 43 and 29% animals in the control, HF and HVHF groups, respectively), neither of haemofiltration doses reversed hyperdynamic circulation, lung dysfunction and ameliorated alterations in gut and kidney microvascular perfusion. Both HF and HVHF failed to attenuate sepsis-induced alterations in surrogate markers of cellular energetics, nitrosative/oxidative stress, endothelial injury or systemic inflammation. In this porcine model of septic shock early HVHF proved superior in preventing the development of septic hypotension. However, neither of haemofiltration doses was capable of reversing the progressive disturbances in microvascular, metabolic, endothelial and lung function, at least within the timeframe of the study and severity of the model.

Introduction Our understanding of septic acute kidney injury (AKI) remains incomplete. A fundamental step is the use of animal models designed to meet the criteria of human sepsis. Therefore, we dynamically assessed renal haemodynamic, microvascular and metabolic responses to, and ultrastructural sequelae of, sepsis in a porcine model of faecal peritonitis-induced progressive hyperdynamic sepsis. Methods In eight anaesthetised and mechanically ventilated pigs, faecal peritonitis was induced by inoculating autologous faeces. Six sham-operated animals served as time-matched controls. Noradrenaline was administered to maintain mean arterial pressure (MAP) greater than or equal to 65 mmHg. Before and at 12, 18 and 22 hours of peritonitis systemic haemodynamics, total renal (ultrasound Doppler) and cortex microvascular (laser Doppler) blood flow, oxygen transport and renal venous pressure, acid base balance and lactate/pyruvate ratios were measured. Postmortem histological analysis of kidney tissue was performed. Results All septic pigs developed hyperdynamic shock with AKI as evidenced by a 30% increase in plasma creatinine levels. Kidney blood flow remained well-preserved and renal vascular resistance did not change either. Renal perfusion pressure significantly decreased in the AKI group as a result of gradually increased renal venous pressure. In parallel with a significant decrease in renal cortex microvascular perfusion, progressive renal venous acidosis and an increase in lactate/pyruvate ratio developed, while renal oxygen consumption remained unchanged. Renal histology revealed only subtle changes without signs of acute tubular necrosis. Conclusion The results of this experimental study argue against the concept of renal vasoconstriction and tubular necrosis as physiological and morphological substrates of early septic AKI. Renal venous congestion might be a hidden and clinically unrecognised contributor to the development of kidney dysfunction.