Should continuous renal replacement therapy be used for 'non-renal' indications in critically ill patients with shock?

"Awake" Extracorporeal Membrane Oxygenation Combined With Continuous Renal Replacement Therapy For the Treatment of Severe Chemical Gas Inhalation Lung Injury

Lung injury caused by chemical gas inhalation is a common clinically severe disease that very easily progresses to acute respiratory distress syndrome (ARDS). Traditional respiratory support consists mainly of mechanical ventilation, but the prognosis of this condition is still poor. "Awake" extracorporeal membrane oxygenation (ECMO) maintains oxygenation, improves ventilation, adequately allows the injured lungs to rest, and avoids complications associated with sedation, intubation, and mechanical ventilation. Continuous renal replacement therapy (CRRT) can provide better fluid management and reduce pulmonary edema. Herein, we describe the case of a patient with severe chemical gas inhalation lung injury who failed to respond to traditional mechanical ventilation and was subsequently treated with awake ECMO combined with CRRT.

Effects of Early Continuous Venovenous Hemofiltration on E-Selectin, Hemodynamic Stability, and Ventilatory Function in Patients with Septic-Shock-Induced Acute Respiratory Distress Syndrome

Objective. To investigate the effects of 72-hour early-initiated continuous venovenous hemofiltration (ECVVH) treatment in patients with septic-shock-induced acute respiratory distress syndrome (ARDS) (not acute kidney injury, AKI) with regard to serum E-selectin and measurements of lung function and hemodynamic stability. Methods. This prospective nonblinded single institutional randomized study involved 51 patients who were randomly assigned to receive or not receive ECVVH, an ECVVH group (n = 24) and a non-ECVVH group (n = 27). Besides standard therapies, patients in ECVVH group underwent CVVH for 72 h. Results. At 0 and 24 h after initiation of treatment, arterial partial pressure of oxygen/fraction of inspired oxygen (PaO₂/FiO₂) ratio, extravascular lung water index (EVLWI), and E-selectin level were not significantly different between groups (all P > 0.05). Compared to non-ECVVH group, PaO₂/FiO₂ is significantly higher and EVLWI and E-selectin level are significantly lower in ECVVH group (all P < 0.05) at 48 h and 72 h after initiation of treatment. The lengths of mechanical ventilation and stay in intensive care unit (ICU) were shorter in ECVVH group (all P < 0.05), but there was no difference in 28-day mortality between two groups. Conclusions. In patients with septic-shock-induced ARDS (not AKI), treatment with ECVVH in addition to standard therapies improves endothelial function, lung function, and hemodynamic stability and reduces the lengths of mechanical ventilation and stay in ICU.

High-volume hemofiltration reduces the expression of myocardial tumor necrosis factor-alpha in septic shock pigs

Increasing evidence indicates that the expression of tumor necrosis factor-α (TNF-α) in myocardium correlates with the severity of cardiac dysfunction in septic shock. The aim of this study was to investigate the impact of high-volume hemofiltration (HVHF) on the expression of TNF-α in myocardium in septic shock pigs. Sixteen male Landrace pigs weighing 31 ± 5 kg were randomly assigned to control group (n = 4), septic shock group (n = 6), and HVHF group (septic shock + HVHF, n = 6). All animals were anesthetized and mechanically ventilated. After baseline examinations, septic shock group and HVHF group underwent induction of peritonitis. One hour later, the animals in HVHF group received treatment with HVHF and the treatment was continued for 12 h. As the control of HVHF group, the animals in septic shock group received the same support but hemofiltration. Twelve hours after HVHF therapy, all the animals were sacrificed. TNF-α and nitric oxide (NO) levels in both circulation and myocardium were measured. Compared with those of septic shock animals, the levels of cardiac output, stroke volume, and mean arterial pressure were better maintained in HVHF group. The expression of TNF-α in myocardium in HVHF group was lower than that in septic shock group (44.17 ± 18.70 vs. 92.50 ± 33.89 pg/mg protein, P = 0.015). The difference of TNF-α in circulation between HVHF group and septic shock group was no significance at different time. However, circulating NO in HVHF group was lower than that in septic shock group. These results suggest that HVHF improves hemodynamics and heart dysfunction in septic shock pigs, which may be attributed to reduction of TNF-α in myocardium but not in circulation.

Continuous veno-venous haemofiltration attenuates myocardial mitochondrial respiratory chain complexes activity in porcine septic shock

Increasing evidence indicates that mitochondrial dysfunction plays an important role in modulating the development of septic shock. In the present study, we investigated whether continuous veno-venous haemofiltration (CVVH) with high-volume might improve myocardial mitochondrial dysfunction in a porcine model of peritonitis-induced septic shock. Sixteen male Landrace pigs weighing 31 +/- 5 kg were randomly assigned to normal control group (n = 4), peritonitis group (n = 6) and peritonitis plus CVVH group (n = 6). All animals were anaesthetised and mechanically ventilated. After baseline examinations, the peritonitis group and the peritonitis plus CVVH group underwent induction of peritonitis. One hour later, the animals in the peritonitis plus CVVH group received treatment with high-volume CVVH. Twelve hours after treatment, the animals were sacrificed. Animals in the peritonitis group were killed 13 hours after induction of peritonitis. Peritonitis challenge induced septic shock associated with increased blood lactate and high-volume CVVH improved lactate acidosis. Compared with the peritonitis group, cardiac output, stroke volume and mean arterial pressure were better maintained in peritonitis plus CVVH group. More importantly, high-volume CVVH improved myocardial mitochondrial complex I activity (0.22 +/- 0.03 vs. 0.15 +/- 0.04, P = 0.04). These results suggest that high-volume CVVH improves haemodynamics and heart dysfunction in septic shock and the improvement may be attributed to amelioration of myocardial mitochondrial dysfunction.

Continuous renal replacement therapy in patients following traumatic injury

In critically injured patients, the incidence of acute renal failure has been reported to occur in as many as 31% of patients. The use of CRRT modalities for patients following traumatic injuries is becoming more common, albeit slowly, and this therapy may impact upon long-term recovery of renal function and mortality. Historical studies investigating the early use of intermittent dialysis reported significant improvement in survival in patients who were dialyzed earlier and more vigorously than in control subjects. Early trauma patients also showed improved survival following war injuries when dialyzed prophylactically. Although there is a growing acceptance in favor of earlier renal replacement therapy, the published consensus and the practice in many centers has been to dialyze/filter relatively ill rather than relatively healthy patients. The R Adams Cowley Shock Trauma Center (STC) in Baltimore, Maryland, USA, admits over 8,000 trauma patients each year. Within the STC, a program of continuous renal replacement therapy was established in the early 1980's. We review both historical and current literature on the use of renal replacement therapies after traumatic injury, and suggest some future areas of investigation and indications for these modalities.

An aggressive systematic strategy for acute respiratory distress syndrome caused by severe pneumonia after renal transplantation

Acute respiratory distress syndrome (ARDS) caused by pneumonia after renal transplantation was usually associated with overimmunosuppression and high mortality rate. We evaluated the efficacy of an aggressive systemic protocol including strategies improving body's immune function. Twenty-one recipients were enrolled in this study. Patients were subjected to a protocol including (i) withdrawal of most immunosuppressants, (ii) early use of immunoenhancers and continuous renal replacement therapy (CRRT), (iii) reasonable administration of antibiotic regimen, (iv) prompt mechanical ventilating strategy, and (v) adequate nutrition. Immunosuppressants were adjusted according to the value of CD4+, CD8+T lymphocytes in peripheral blood. CRRT was conducted at once when patients were admitted to the intensive care unit (ICU), regardless the graft function. Thirteen (62%) survived and eight died finally. This is a high survival rate for this kind of patients. Eighteen patients had received thymosin treatment. All patients who survived experienced renal allograft dysfunction during CRRT, but when CRRT stopped, the function of all grafts gradually recovered. No acute rejection episodes were documented during the treatment. The aggressive systemic protocol including strategies improving the body's immune function and CRRT can improve the outcome of patients with ARDS after renal transplantation. The count of CD4+, CD8+T lymphocytes of peripheral blood is useful in the adjustment of immunosuppressants and the prediction of patient outcome.

Amelioration of hemodynamics and oxygen metabolism by continuous venovenous hemofiltration in experimental porcine pancreatitis

AIM: To investigate the potential role of continuous venovenous hemofiltration (CVVH) in hemodynamics and oxygen metabolism in pigs with severe acute pancreatitis (SAP).

METHODS: SAP model was produced by intraductal injection of sodium taurocholate [4%, 1 mL/kg body weight (BW)] and trypsin (2 U/kg BW). Animals were allocated either to untreated controls as group 1 or to one of two treatment groups as group 2 receiving a low-volume CVVH [20 mL/(kg.h)], and group 3 receiving a high-volume CVVH [100 (mL/kg.h)]. Swan-Ganz catheter was inserted during the operation. Heart rate, arterial blood pressure, cardiac output, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, central venous pressure, systemic vascular resistance, oxygen delivery, oxygen consumption, oxygen extraction ratio, as well as survival of pigs were evaluated in the study.

RESULTS: Survival time was significantly prolonged by low-volume and high-volume CVVHs, which was more pronounced in the latter. High-volume CVVH was significantly superior compared with less intensive treatment modalities (low-volume CVVH) in systemic inflammatory reaction protection. The major hemodynamic finding was that pancreatitis-induced hypotension was significantly attenuated by intensive CVVH (87.4±12.5 kPa vs 116.3±7.8 kPa, P<0.01). The development of hyperdynamic circulatory failure was simultaneously attenuated, as reflected by a limited increase in cardiac output, an attenuated decrease in systemic vascular resistance and an elevation in oxygen extraction ratio.

CONCLUSION: CVVH blunts the pancreatitis-induced cardiovascular response and increases tissue oxygen extraction. The high-volume CVVH is distinctly superior in preventing sepsis-related hemodynamic impairment.

Dose of Dialysis in Acute Renal Failure

Acute renal failure (ARF) is a cause of significant morbidity and mortality. Despite advances in supportive care, outcomes in ARF have improved little over the past decades. The primary goals in management of patients with ARF are to optimize hemodynamic and volume status, minimize further renal injury, correct metabolic abnormalities, and permit adequate nutrition. Renal replacement therapy (RRT) is often required to achieve these goals while awaiting renal recovery, but the optimal dose of dialysis in patients with ARF is not known. Extrapolation of required dialysis dose from recommendations in chronic dialysis is unlikely to be appropriate because of the lack of a steady state and differences in distribution volume of urea that are intrinsic to ARF. The prescribed dialysis dose in ARF is often low, and actual delivered dose is often even less than prescribed. Delivery of dialysis in ARF is often hampered by the patient's hypercatabolic state, hemodynamic instability, and volume status, as well as suboptimal vascular access with temporary venous catheters. The impact of intermittent hemodialysis (IHD) versus continuous renal replacement therapy (CRRT) on outcomes in ARF is also not clear. Patient disease severity impacts more than dialysis modality in patient outcome, but when patients are stratified for equal disease severity, CRRT may have potential benefits over IHD in terms of patient survival, fluid and metabolic control, and renal recovery. Strategies associated with improved outcomes that have emerged thus far in ARF are to aim for a time-averaged blood urea nitrogen (BUN) of less than 60 mg/dl with IHD, varying IHD frequency as necessary, or to achieve a minimum ultrafiltration rate of 35 ml/kg/hr with CRRT.

Economic aspects of severe sepsis: a review of intensive care unit costs, cost of illness and cost effectiveness of therapy

Severe sepsis remains both an important clinical challenge and an economic burden in intensive care. An estimated 750,000 cases occur each year in the US alone (300 cases per 100,000 population). Lower numbers are estimated for most European countries (e.g. Germany and Austria: 54-116 cases per year per 100,000). Sepsis patients are generally treated in intensive care units (ICUs) where close supervision and intensive care treatment by a competent team with adequate equipment can be provided. Staffing costs represent from 40% to >60% of the total ICU budget. Because of the high proportion of fixed costs in ICU treatment, the total cost of ICU care is mainly dependent on the length of ICU stay (ICU-LOS). The average total cost per ICU day is estimated at approximately 1200 Euro for countries with a highly developed healthcare system (based on various studies conducted between 1989 and 2001 and converted at 2003 currency rates). Patients with infections and severe sepsis require a prolonged ICU-LOS, resulting in higher costs of treatment compared with other ICU patients. US cost-of-illness studies focusing on direct costs per sepsis patient have yielded estimates of 34,000 Euro, whereas European studies have given lower cost estimates, ranging from 23,000 Euro to 29,000 Euro. Direct costs, however, make up only about 20-30% of the cost of illness of severe sepsis. Indirect costs associated with severe sepsis account for 70-80% of costs and arise mainly from productivity losses due to mortality. Because of increasing healthcare cost pressures worldwide, economic issues have become important for the introduction of new innovations. This is evident when introducing new biotechnology products, such as drotrecogin-alpha (activated protein C), into specific therapy for severe sepsis. Data so far suggest that when drotrecogin-alpha treatment is targeted to those patients most likely to achieve the greatest benefit, the drug is cost effective by the standards of other well accepted life-saving interventions.

Continuous renal replacement therapy: opinions and evidence

Continuous arteriovenous haemofiltration (CAVH) is the first example of continuous renal replacement therapy (CRRT). CAVH was first applied for the treatment of diuretic unresponsive fluid overload. Subsequently, CRRT has undergone a remarkable growth, and it is now performed with pump technology (CVVH) and via double-lumen central venous catheters. In many intensive care units, especially in Australia and in Europe, CRRT has become the dominant, if not exclusive, form of artificial renal support. Continuous haemofiltration is now used beyond the original indications of blood purification, for the treatment of certain drug intoxications, for severe cardiac failure, for volume control during, after cardiopulmonary bypass, and to decrease the toxicity of chemotherapy. Furthermore, there is strong ongoing research into its role or that of derived techniques as possible adjuvant therapies during severe sepsis. Despite its large use, the current state of CRRT is surrounded by some controversies, and an effort should be made to give a dispassionate distillation of the literature for a final common definition of what is based on opinions and what carries sufficient evidence.

The dialytic management of acute renal failure in the elderly

In this article the different dialysis strategies in the management of acute renal failure (ARF) in the elderly are discussed. Although peritoneal dialysis (PD) offers some theoretical advantages, there are several medical and technical reasons why it is currently less frequently used. The choice between intermittent hemodialysis (HD) and continuous renal replacement therapy (CRRT) is determined by a number of considerations, the most important ones being hemodynamic stability, the need for hyperalimentation and/or ultrafiltration, and the local experience with one or both techniques. Some recent studies with CRRT in elderly ARF patients describe favorable results. Slow extended daily dialysis (SLEDD) modalities may be particularly indicated in elderly, critically ill ARF patients because these techniques combine the advantages of both CRRT and HD. Finally, the importance of the biocompatibility of dialysis membranes is discussed. Although there are a number of theoretical arguments to use biocompatible membranes, this opinion is not always supported by the results of recent comparative studies. It is the opinion of the authors that all dialysis strategies should be mastered and utilized for appropriate indications in elderly ARF patients.

Perfusion with lipopolysaccharide negative blood eliminates lipopolysaccharide induced lung injury

We investigated whether perfusion with control blood improves pulmonary functions compromised by lipopolysaccharide (LPS) infusion. This was an animal study in a research laboratory at a university hospital by using Sprague-Dawley rats (n = 19), each weighing 325 to 350 g. All animals were pretreated with a 24 hour infusion of either LPS (5 mg/kg) or vehicle, after which, excised lungs were reperfused for 2 hours with either LPS+ or control blood. Three groups were studied: (1) group S (n = 6); LPS pretreated lungs reperfused with LPS containing blood to mimic persistent sepsis, (2) group N (n = 6); LPS pretreated lungs reperfused with control blood to mimic the removal of the septic blood components, and (3) group C (n = 7); vehicle pretreated lungs reperfused with normal blood as a control. Blood gas exchange, shunt fraction (Qs/Qt), alveolar-arterial oxygen gradient (A-aDO2), and variables for lung mechanics were measured. Leukosequestration was quantified with a myeloperoxidase (MPO) assay. The PO2 (mm Hg) values at 90 min after reperfusion in groups S, N, and C were 67.8 +/- 7.0*, 85.2 +/- 9.2, and 90.1 +/- 7.5, respectively (*p < 0.05; vs. group N and C). In addition to PO2, A-aDO2 and Qs/Qt significantly deteriorated in group S. MPO activity in the lungs after LPS infusion was significantly higher than that after vehicle infusion (1.7 +/- 0.3 vs. 0.12 +/- 0.04 units/g tissue; p < 0.001). Subsequent reperfusion with LPS+ blood (group S) increased MPO activity to 3.1 +/- 0.6 (p < 0.05), but reperfusion with normal blood (group N) caused a significant decrease to 1.1 +/- 0.2 (p < 0.05). MPO activity in group C did not significantly change compared with those after vehicle infusion. Reperfusion with control blood normalized lung function compromised by pretreatment with LPS and significantly reduced leukosequestration. These results favor the possibility that the removal of LPS+ blood components may eliminate septic lung injury.

Continuous haemofiltration in the intensive care unit

Continuous renal replacement therapy (CRRT) was first described in 1977 for the treatment of diuretic-unresponsive fluid overload in the intensive care unit (ICU). Since that time this treatment has undergone a remarkable technical and conceptual evolution. It is now available in most tertiary ICUs around the world and has almost completely replaced intermittent haemodialysis (IHD) in some countries. Specially made machines are now available, and venovenous therapies that use blood pumps have replaced simpler techniques. Although, it remains controversial whether CRRT decreases mortality when compared with IHD, much evidence suggests that it is physiologically superior. The use of CRRT has also spurred renewed interest in the broader concept of blood purification, particularly in septic states. Experimental evidence suggests that this is a promising approach to the management of septic shock in critically ill patients. The evolution and use of CRRT is likely to continue and grow over the next decade.

The effect of intensive plasma water exchange by hemofiltration on hemodynamics and soluble mediators in canine endotoxemia

High volume hemofiltration (HVHF) (200 ml/kg/h) improves hemodynamics in experimental septic shock but is difficult to apply clinically. Accordingly, we studied whether less intensive HVHF (80 ml/kg/h) can still improve hemodynamics in experimental septic shock. We also investigated its effect on the serum concentrations of several inflammatory mediators, including endothelin (ET-1), endotoxin (LPS), tumor necrosis factor-alpha (TNF-alpha), and 6-keto prostaglandin F(1alpha) (6-kepto PGF(1alpha)). Sixteen anesthetized dogs were connected to a continuous veno-venous hemofiltration (CVVH) (filtration: 80 ml/kg/h) or sham circuit and endotoxin (0.5 mg/kg) was infused intravenously over 5 min. Hemodynamic variables were measured at baseline and at 15, 45, 90, and 180 min. The major hemodynamic finding was that endotoxin-induced hypotension was significantly attenuated by intensive CVVH (p < 0.04). Changes in cardiac output and right ventricular ejection fraction were equal in both groups. ET-1 levels, but not LPS, TNF-alpha, or 6-keto PGF(1alpha), were lower during CVVH (p = 0.042). Endotoxin or TNF-alpha were not found in the ultrafiltrate. Median clearances of ET-1 and 6-keto PGF(1alpha) during intensive CVVH were 8.8 and 25.9 ml/m, respectively. We conclude that intensive CVVH attenuates the early component of endotoxin-induced hypotension and reduces serum concentrations of endothelin-1. The effect of CVVH on blood pressure is not explained by convective clearance of the mediators in question.

New perspectives for prevention/treatment of acute renal failure

Acute renal failure continues to be a difficult clinical problem in critically ill patients, despite advances in critical care and dialysis. This review focuses on some of the current issues in the nondialytic and dialytic management of these patients. Critical analysis of some still frequently used drugs in these patients such as diuretics and dopamine in so-called 'renal doses' has revealed little beneficial effect. Recent data are in conflict with previous suggestions that biocompatible membranes have a positive effect on the recovery of renal function and on patient mortality. The choice between intermittent haemodialysis and continuous renal replacement therapy should be made on an individual basis and not on the basis of 'dogmatic' opinion.

Non-renal indications for continuous renal replacement therapy

While there is clear support for the use of continuous renal replacement therapy (CRRT) in critically ill acute renal failure patients, there are other illnesses without renal involvement where CRRT might be of value. These include sepsis and other inflammatory syndromes such as acute respiratory distress syndrome (ARDS) and cardiopulmonary bypass where removal of inflammatory mediators by hemofiltration is hypothesized to improve outcome. Adsorption appears to be the predominant mechanism of mediator elimination. However, the observed hemodynamic improvement can, at least partially, be attributed to a reduction of body temperature or to fluid removal, and the evidence for a clinically important removal of proinflammatory cytokines remains limited. Continuous and therefore smooth fluid removal may improve organ function in ARDS, after surgery with cardiopulmonary bypass, and in patients with refractory congestive heart failure. Continuous removal of endogenous toxins, eventually combined with intermittent hemodialysis, is probably beneficial in inborn errors of metabolism, severe lactic acidosis, or tumor lysis syndrome.

Effect of haemofiltration on pathological fibrinolysis due to severe sepsis: a case report

Bleeding due to coagulopathy is a frequent complication of severe sepsis, especially in burn patients. The primary treatment is aimed at the underlying cause but additional supportive measures, consisting mainly of coagulation factor replacement, are frequently necessary. We describe the salutary effect of continuous veno-venous haemofiltration (CVVH) with predilution on diffuse haemorrhage in a patient with severe septic shock and renal failure. The diffuse haemorrhage was initially treated with replacement of coagulation factors. Prothrombin time and partial thromboplastin time became normal while diffuse bleeding continued and the thrombelastogram showed evidence of fibrinolysis. A short period of CVVH lead to the cessation of bleeding which was reflected by a normal thrombelastogram.