Continuous renal replacement therapy for critically ill patients: an update

Improvement of monocyte function and immune homeostasis by high volume continuous venovenous hemofiltration in patients with severe acute pancreatitis

BACKGROUND

Continuous renal replacement therapy (CRRT) showed promising results in the management of critically ill patients with systemic inflammatory response syndrome (SIRS)/sepsis. However, the underlying mechanism is still not very clear. A change of immune homeostasis in critically ill patients during CRRT was observed only to a smaller degree.

OBJECTIVE

The purpose of this study was to test the hypothesis that high-volume continuous venovenous hemofiltration (HV-CVVH) treatment could improve monocyte function and restore immune homeostasis in patients with severe acute pancreatitis (SAP).

METHODS

This was a prospective clinical trial in the surgical intensive care unit of a teaching hospital. Subjects were 16 patients with severe acute pancreatitis: sepsis group (n=7): positive culture result and in the late phase of disease (from onset of SAP to receiving CVVH therapy: more than 3 days); and nonseptic group (n=9): negative culture result and early phase of disease (less than 3 days). Patients received 72 hours of HV-CVVH. We measured the change in mean arterial pressure, APACHE II score, monocyte functions (including antigen-presenting and cytokine production ability), and plasma cytokines.

RESULTS

Mean arterial pressure were stable accompanied with APACHE II score improvements. HLA-DR expression on monocytes (antigen-presenting ability) were markedly decreased (p<0.0001) in all patients. Lipopolysaccharide (LPS)-induced TNF-alpha, interleukin-6 (IL-6), and IL-10 production from patients' monocytes markedly decreased in septic patients, but significantly increased in nonseptic patients. During HV-CVVH treatment, HLA-DR expression was markedly increased in nonseptic patients in 24 hours (p<0.05), and in septic patients in 72 hours (p<0.05). LPS-induced cytokine production was decreased in nonseptic patients, but not significantly changed in septic patients. The change of plasma cytokines showed the same trend.

CONCLUSIONS

In patients with SAP, HV-CVVH was associated with improved hemodynamics. HV-CVVH restores monocytes functions, especially in patients in the early phase of the disease and without sepsis. These findings suggest a potential role for HV-CVVH in the treatment of SAP.

Renal disease in patients with cancer

Kidney disease is very common in patients with cancer. Nephrologists are vital members of the multidisciplinary care team for these patients. Given the high prevalence of comorbidities in patients treated for active malignancy, it is not surprising that these individuals frequently develop renal diseases that are common among other hospitalized patients, such as those arising from sepsis, hypotension or use of nephrotoxic agents (e.g. radiocontrast or antimicrobial agents). The role of the nephrologist in these cases differs little with respect to the presence or absence of cancer. On the other hand, there are several renal syndromes that are unique to patients with cancer, being caused either by the cancer itself or by its treatment. These syndromes are reviewed here. In addition, patients who are receiving chemotherapy often require dialysis for either acute or chronic kidney disease. Unfortunately, there is very little information on the clearance characteristics of most chemotherapeutic agents. In cancer patients with renal disease, both the timing of administration and the dose-adjustment of chemotherapy must rely on clinical experience and close clinical observation.

The diagnosis of acute renal failure in intensive care: mongrel or pedigree?

Acute renal failure is common in the intensive care unit; it is well recognised that patients who develop acute renal failure have a high mortality rate. While there have been improvements in the management of acute renal failure, the mortality remains high. Acute renal failure is easily diagnosed biochemically and clinically but it is not a single disease entity. It is a syndrome that affects a very heterogeneous population. Studies of acute renal failure and of the impact of renal replacement therapy in intensive care are usually inconclusive, which may be the natural consequence of studying a syndrome. This article focuses on the more uncertain features of acute renal failure, the problems of investigating acute renal failure as a disease and the difficulties of applying the results of a study of a heterogeneous population to the management of individuals.

Acute renal failure in children and infants

PURPOSE OF REVIEW

This review provides an overview of various topics related to acute renal failure and summarizes the results of recent advancements of particular significance in the care of children with acute renal failure.

RECENT FINDINGS

Over the past two decades, the treatment and prognosis of children with acute renal failure has notably shifted owing to advances in continuous treatment modalities, improvements in vascular access, and increased acknowledgment and understanding of the importance of optimizing nutritional support.

SUMMARY

After discussing the various causes of acute renal failure in children and infants, this review focuses on recent advancements in the management of acute renal failure, including acute dialysis modalities and continuous renal replacement therapy.

Preventing hypothermia during continuous veno-venous haemodiafiltration: a randomized controlled trial

BACKGROUND

Continuous veno-venous haemodiafiltration is a common form of dialysis used in intensive care units. Unfortunately, patients often experience hypothermia as a side-effect of the therapy because of the necessity for extracorporeal blood flow. Intensive care nurses aim to prevent hypothermia developing. Intravenous fluid warmers are sometimes added to the dialysis circuit in an attempt to maintain patient temperature. However, the efficacy of this method has not been previously studied.

AIM

This paper reports a study to investigate whether intravenous fluid warmers prevent hypothermia during continuous veno-venous haemodiafiltration.

METHOD

A prospective randomized controlled trial was carried out in the intensive care unit of a metropolitan, tertiary-referral, teaching hospital. After Ethics Committee approval, 60 circuits in continuous veno-venous haemodiafiltration mode (200 mL/minute blood flow, 1 L/hour countercurrent dialysate, 3 L/hour pump-controlled ultrafiltration and prefilter fluid replacement of 1.7-2.0 L/hour) were studied. Circuits were randomized to have either an intravenous fluid warmer set at 38.5 degrees C on the dialysate and 1 L/hour of replacement fluid lines or no fluid warmer. Patient core temperature was recorded at baseline and then hourly. Hypothermia was defined as a core temperature <36.0 degrees C.

RESULTS

Mean core temperature loss did not vary between circuits with or without a fluid warmer (0.92 degrees C vs. 1.11 degrees C, P = 0.339). Survival analysis found no difference in hypothermia incidence between groups (log rank = 0.47, d.f. = 1, P = 0.491). Lower baseline temperature (RR 0.142, 95% CI 0.044, 0.459, P = 0.001) and female gender (RR 0.185, 95% CI 0.060, 0.573, P = 0.003) were significant risks for hypothermia.

CONCLUSIONS

Intravenous fluid warmers used as described do not prevent hypothermia during continuous veno-venous haemodiafiltration. Female patients and those with a low-normal baseline temperature are most likely to become hypothermic during this form of dialysis. Further research is needed to address effective ways of preventing hypothermia in critically ill patients receiving continuous renal replacement therapies.

Continuous Renal Replacement Therapy for Management of Overhydration in Heart Failure

An estimated 4.8 million Americans are diagnosed with heart failure. Of those, 5% to 10% meet criteria for the refractory state of the disease. While therapeutic interventions continue to evolve with the changing conceptualization of heart failure pathophysiology, overhydration and its deleterious sequelae remain a problem for those in the refractory state. The incidence of heart failure continues to rise in older individuals. As baby-boomers age across America, greater focus on new, more effective therapies must be considered for treatment of this disease. Continuous renal replacement therapy (CRRT) is one such treatment. The gentle removal of fluid and metabolites while maintaining electrolyte balance helps reduce the effects of overhydration in patients with heart failure. Increasing use of the therapy in the refractory state of heart failure is generating support for early initiation as it continues to demonstrate positive effects. Reduction in edema, attenuation of the sympathoadrenal cascade, and improved respiratory status have all been documented using the therapy. The intent of this article is to provide information for advanced practice nurses and direct care providers regarding CRRT for the treatment of heart failure refractory to typical therapy.

Clinical effects of continuous high volume hemofiltration on severe acute pancreatitis complicated with multiple organ dysfunction syndrome

AIM: To investigate the efficiency of continuous high volume hemofiltration (HVHF) in the treatment of severe acute pancreatitis (SAP) complicated with multiple organ dysfunction syndrome (MODS).

METHODS: A total of 28 SAP patients with an average of 14.36 ± 3.96 APACHE II score were involved. Diagnostic criteria for SAP standardized by the Chinese Medical Association and diagnostic criteria for MODS standardized by American College of Chest Physicians (ACCP) and Society of Critical Care Medicine (SCCM) were applied for inclusion. HVHF was started 6.0 ± 6.1 (1-30) days after onset of the disease and sustained for at least 72 h, AN69 hemofilter (1.2 m²) was changed every 24 h. The ultrafiltration rate during HVHF was 4000 mL/h, blood flow rate was 250-300 mL/min, and the substitute fluid was infused with pre-dilution. Low molecular weight heparin was used for anticoagulation.

RESULTS: HVHF was well tolerated in all the patients, and lasted for 4.04 ± 3.99 (3-24) days. 20 of the patients survived, 6 patients died and 2 of the patients quited for financial reason. The ICU mortality was 21.4%. Body temperature, heart rate and breath rate decreased significantly after HVHF. APACHE II score was 14.4 ± 3.9 before HVHF, and 9.9 ± 4.3 after HVHF, which decreased significantly (P < 0.01). Partial pressure of oxygen in arterial blood before HVHF was 68.5 ± 19.5 mmHg, and increased significantly after HVHF, which was 91.9 ± 25 mmHg (P < 0.01). During HVHF the hemodynamics was stable, and serum potassium, sodium, chlorine, glucose and pH were at normal level.

CONCLUSION: HVHF is technically possible in SAP patients complicated with MODS. It does not appear to have detrimental effects and may have beneficial effects. Continuous HVHF, which seldom disturbs the hemodynamics and causes few side-effects, is expected to become a beneficial adjunct therapy for SAP complicated with MODS.

Acute renal failure in the ICU: assessing the utility of continuous renal replacement

Acute renal failure (ARF) in the ICU patient still remains a common problem and is associated with increased morbidity, mortality, and cost. Potential advantages of continuous renal replacement (CRRT), compared with intermittent hemodialysis (IHD) include enhanced hemodynamic stability, increased solute removal, and greater ultrafiltration. Although it was hoped that CRRT would lead to improvement in patient outcomes, there are few prospective, randomized clinical studies comparing this modality with conventional hemodialysis in the treatment of patients with ARF. The difficulties associated with designing such prospective studies are the complex status of the medical patients and the ethical dilemma of randomizing patients to a certain dialysis modality. At this time, there is no evidence to support the assertion that CRRT improves clinical outcomes compared with IHD.

Acute renal failure in the intensive care unit: a systematic review of the impact of dialytic modality on mortality and renal recovery

BACKGROUND

There is controversy about which dialytic modality should be used for the treatment of acute renal failure (ARF) in the intensive care unit. We performed a systematic review and meta-analysis to determine the relative risks (RRs) of mortality and renal recovery associated with intermittent hemodialysis (IHD) therapy compared with continuous renal replacement therapy (CRRT) in critically ill adults with ARF.

METHODS

Four databases (MEDLINE, Cochrane Library, Database of Abstracts and Reviews, and Science Citation Index), hand searching of conference proceedings and journals, manual review of bibliographies from identified articles, and contact with experts were used. All randomized trials (published or unpublished in any language) that compared mortality between intermittent and continuous treatments were eligible. Trials for which an RR for mortality could not be calculated or with multiple experimental interventions were excluded. Data were extracted separately by two authors and recorded on a standardized form. Disagreements were resolved by consensus.

RESULTS

Six eligible trials were identified; four of these provided data on renal outcomes. RR (mortality) for IHD was 0.96 (95% confidence interval [CI], 0.85 to 1.08; P = 0.50), RR (renal death) was 1.02 (95% CI, 0.89 to 1.17; P = 0.78), and RR (dialysis dependence) in survivors was 1.19 (95% CI, 0.62 to 2.27; P = 0.60; all compared with continuous therapy). Several sensitivity analyses did not change these results. Of the outcomes studied, the risk for dialysis dependence in survivors would be most sensitive to the addition of new trials.

CONCLUSIONS

In comparison to IHD therapy, CRRT does not improve survival or renal recovery in unselected critically ill patients with ARF. Future studies should focus on well-defined subgroups of such patients using lessons learned from the trials in this meta-analysis. The high cost of chronic dialysis therapy and the relative instability of the RR for dialysis dependence suggest that future trials also should evaluate differences in renal recovery between dialytic modalities.

Acute renal failure and dialysis in the chronically critically ill patient

Acute renal failure is a common clinical problem in the intensive care unit (ICU) and is associated with significant morbidity and mortality. There is no "magic bullet" to prevent acute renal failure or to modify the clinical course of established renal failure. The approach to therapy is directed to the early initiation of dialysis therapy. Continuous dialysis therapy is becoming the preferred form of dialysis in the ICU.

Influence of continuous hemofiltration on the hemodynamics of trauma patients

BACKGROUND

The aim of this prospective randomized controlled study was to investigate the effects of continuous venovenous hemofiltration on the hemodynamics and respiratory function of critically ill trauma patients with multiple organ dysfunction syndrome.

METHODS

Thirty consecutive critically ill, mechanically ventilated, trauma patients with multiple organ dysfunction syndrome (without kidney failure) who had invasive hemodynamic monitoring for management of hypotension or hypoxemia were randomized to treatment with or without continuous venovenous hemofiltration. Hemodynamics profile was recorded immediately before and at 6, 12, 24, and 48 hours after the hemofiltration was started (mean of three set data each time). No changes in ventilatory parameters were performed during the study.

RESULTS

Thirty patients were analyzed (15 with and 15 without hemofiltration). Both groups were similar in age (36 +/- 18 versus 36 +/- 14 years) and severity scores (Injury Severity Score, 32 +/- 16 versus 30 +/- 11; Acute Physiology and Chronic Health Evaluation II score, 22 +/- 7 versus 21 +/- 6; Goris score, 5.2 +/- 1.7 versus 5.2 +/- 1.8) and received similar inotropic support. We found a significant improvement in mean arterial pressure (80 +/- 9 to 94 +/- 8 (mm Hg), p = 0.01) and partial pressure of oxygen in arterial blood/inspiratory oxygen supply index (124 +/- 40 to 204 +/- 44, p = 0.03) in the intervention group during the study period. We did not find any other significant change in variables studied.

CONCLUSIONS

Continuous venovenous hemofiltration is associated with a significant improvement in hemodynamic and respiratory variables in critically ill trauma patients with multiple organ dysfunction syndrome. This improvement can help in the management of these patients. Further work is necessary to define whether this technique can reduce the high mortality of this disease.

Intermittent versus continuous treatment for acute renal failure: where do we stand?

Despite impressive advances in the field of general intensive care and in the techniques available for the treatment of acute renal failure (ARF), particularly the development of continuous renal replacement therapies (CRRT), it is suggested that outcome of ARF patients has remained similar to that observed 2 or more decades ago. This article focuses on the impact of several factors, including the dialysis regimen, on outcome in ARF patients in a recent time period compared with an earlier period to assess whether a change has occurred in the patient population, dialysis regimen, or renal and patient outcome. Critical differences between intermittent hemodialysis (IHD) and CRRT and the authors' preference for continuous venovenous hemofiltration (CWH) are explained. However, using the APACHE II score and more specifically use of the ratio between this score at 2 different time points (ICU admission v time of start of dialysis), the need for an easy-to-use and reliable severity-of-illness score to allow adequate comparison of patient groups or treatment strategies is emphasized. Using data from a recent survey, attention is also given to the implementation of acute dialytic support, particularly CRRT, in the Netherlands.

CRRT in the area of cost containment: is it justified?

Intensive care accounts for at least 25% of health care costs. One third of this goes to 10% of patients who, in general, have combined respiratory and renal failure. The cost of renal replacement therapy is, therefore, of major importance. Continuous renal replacement therapy (CRRT) has many potential advantages over intermittent hemodialysis (IHD). These include better nutritional support, better volume maintenance, reduction of extravascular lung water, and potential clearance of inflammatory mediators. To date, noncomparative trials have suggested a trend toward decreased mortality. Randomized trials have suggested a CRRT mortality and morbidity benefit, but only when comparing long-term renal recovery. Acute mortality benefit has not been clearly established and, as such, cost comparison is of increased interest. Cost comparison trials are complicated, but some recent studies have led to the conclusion that costs are comparable. Others have concluded that CRRT is slightly more expensive. When comparing randomized patients in a recent prospective trial, aggregate costs for renal replacement therapy were comparable. The advantages of better nutrition, better fluid balance, easier management of hemodynamics, and more complete renal recovery, as suggested by this study, should continue to make it valuable. Physician acceptance of CRRT advantages has been established and suggests clinical benefit despite any potential increased cost.

Impact of continuous hemofiltration on cytokines and cytokine inhibitors in oliguric patients suffering from systemic inflammatory response syndrome

The impact of continuous hemofiltration (CHF) using a polyacrylonitrile membrane on the kinetics of tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta), and their inhibitors (soluble TNF receptors [sTNFrI, sTNFrII], interleukin-1 receptor antagonist [IL-1Ra]) was assessed in nine oliguric patients suffering from systemic inflammatory response syndrome. Blood and plasma flow (Qb, Qp), sieving coefficient (SC), plasma and ultrafiltrate clearances (Kp, Kuf), and plasma extraction rates (ERp) were calculated at different time points using standard formulas. No significant improvement of hemodynamics or gas exchange was noted following HF but a significant increase in serum bicarbonate occurred after 24 h (P < 0.05). TNF alpha was detected in plasma from all patients (153 +/- 2.3 pg/mL [mean +/- SEM]). None of the patients had detectable IL-1 beta levels. High levels of the TNF receptors (sTNFrI 20.338 +/- 2.431 pg/mL; sTNFrII 17.839 +/- 2.630 pg/mL) and IL-1Ra (19.775 +/- 3.943 pg/mL) were found in all patients. Upon initiation of hemofiltration (HF), the mean individual sTNFrI/TNF alpha ratio amounted to 269 +/- 84.6 and the sTNFrII/TNF alpha ratio to 249 +/- 91.8. Mean ultrafiltrate volume (Vuf) was 11.8 +/- 0.4 L/day. Appreciable sieving of IL-1Ra (SC 0.45 +/- 0.10), but not of the other cytokines, was noted (SC TNF alpha, sTNFrI, sTNFrII < 0.09). Despite minimal Kuf of TNF alpha, sTNFrI, and STNFrII (Kuf < 0.8 mL/min), appreciable Kp was noted, suggesting that membrane adsorption occurs (Kp approximately 8 mL/min). There was a nonsignificant increase of the ratios between both TNF receptors and TNF alpha across the filter (sTNFrI/TNF alpha ratio [pre] 231 +/- 37.9 versus [post] 312 +/- 75.3); sTNFrII/TNF alpha ratio [pre] 211 +/- 42.1 versus [post] 291 +/- 79.3). Appreciable Kp of IL-1Ra was noted (Kp 17.3 +/- 1.61 mL/min), which was only in part due to Kuf (4.0 +/- 0.86 mL/min). There was a significant decrease of IL-1Ra levels across the membrane, both overall ([pre] 20.223 +/- 2.282 versus [post] 16.637 +/- 2.039 pg/mL; P < 0.01) and at different time points (P < 0.01). Only for IL-1Ra was significant extraction from plasma noted (ERp 26 +/- 6.0%). Plasma levels of TNF alpha, sTNFrI, sTNFrII, and IL-1Ra were not altered by 24 h of CHF. In conclusion, both cytokines and cytokine inhibitors can be removed from the circulation, either by convective transport or by membrane adsorption. Using low-volume HF (Vuf approximately 12 L/day), no impact on cytokine plasma levels nor the patients hemodynamics or gas exchange was noted. The appreciable SC of IL-1Ra (0.45), however, suggests that HF with high(er) UF volumes (> 50 L/day) may be able to achieve reductions in plasma levels of some peptide (anti)mediators. However, whether this aspecific elimination of both mediators and antimediators may alter the clinical course in critically ill patients remains to be investigated.

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

Accumulating experience with the use of continuous renal replacement therapy (CRRT) in critically ill patients with acute renal failure suggests that these treatment modalities have distinct advantages relative to conventional dialysis in terms of solute clearances, fluid removal and hemodynamics, which may translate in improved renal and patient outcome. Recent data point to a possible beneficial effect of CRRT on the clinical course, independent from an impact on fluid balance, in critically ill patients with shock which is attributed to the continuous elimination of inflammatory mediators from the circulation. This has raised the question as to whether CRRT might be used for 'non-renal' indications such as the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). In some animal models of experimental septic and non-septic shock, (short-term) hemodialysis and hemofiltration were found to improve hemodynamics and/or gas exchange. However, data were inconsistent and the clinical relevance questionable. Observations from both uncontrolled and controlled clinical studies (comprising only a small number of patients) support the hypothesis that CRRT may exert beneficial effects on the clinical course in critically ill patients with SIRS and MODS, independent from volume removal. Although several mediators known to play a role in the development of SIRS/MODS may pass hemofiltration membranes, quantitative data on the extent of its extracorporeal clearance relative to the production rate and endogenous clearance is often lacking. In addition, this aspecific elimination with CRRT may also effect levels of anti-mediators, which may be harmful. Ultrafiltrate properties include depression of cardiac performance, induction of proteolysis and immunosuppressive activity suggesting that water-soluble factors responsible for these deleterious effects are removed from the circulation by convection. However, no significant survival advantage has yet been shown for critically ill patients with SIRS/MODS when treated with CRRT as an adjunct to conventional therapy. Only prospective controlled studies of appropriate sample size, which requires a multicenter approach, might answer the question whether use of CRRT may alter the clinical course and outcome in critically ill patients with SIRS and MODS. Until such studies are performed, the rationale for the use of CRRT in the absence of conventional indications for dialytic support remains unproven.

Prognostic indexes and mortality in critically ill patients with acute renal failure treated with different dialytic techniques

The objective of this study was to compare the evolution of patients with acute renal failure (ARF) treated conservatively or with different dialytic techniques in an intensive care unit (ICU). From June 1992 to November 1994, 1087 consecutive patients were admitted in our ICU. Two hundred and twenty of these presented with ARF, and were divided into three groups; group I (control group): 156 patients with ARF who did not receive substitutive techniques; group II: 21 patients under intermittent hemodialysis (IHD) or peritoneal dialysis (PD); group III: 43 patients under continuous hemodiafiltration (CHDF). The studied variables were age, etiology of renal failure, requirement of dialysis, type of dialysis, length of ICU and hospital stay, and renal function outcome. APACHE II and SAPS scores were recorded on admission and analyzed for hospital mortality. Chi-square test and the analysis of variance were used for the statistical analysis. Results are presented as mean +/- SD. A p value below 0.05 was considered statistically significant. Although etiology of ARF was multifactorial, we found a high frequency of ARF due to sepsis (56.8%), hypoperfusion (58.7%), and acute tubular necrosis (62.5%). Sepsis and heart failure were clinical conditions associated to a greater mortality. We did not find any statistical difference between the two dialyzed groups for all the studied variables, nor between the three groups regarding APACHE II and hospital stay. Significant differences were found between dialyzed and non-dialyzed patients respect to age, group I: 64.1 +/- 13.6, group II: 56.4 +/- 19.7, and group III: 56.0 +/- 14.1 (p < 0.001), creatinine peak serum levels, group I: 260 +/- 130, group II: 494 +/- 209, and group III: 441 +/- 170 mumol/L (p < 0.0001), and mortality, group I: 46.9%, group II: 66.7%, and group III: 76.2% (p < 0.002). SAPS score showed differences between the control group and the CHDF group 13.9 +/- 4.8 and 16.4 +/- 5.4 (p < 0.007), respectively. The use of dialytic techniques in critically ill ARF patients is associated with greater mortality. Prognostic indexes on admission did not correctly classify our patients with ARF. Continuous hemodiafiltration does not involve greater mortality or length of stay as compared to conventional dialysis.

Use of APACHE II classification to evaluate outcome and response to therapy in acute renal failure patients in a surgical intensive care unit

The study objective was to determine the applicability of the acute physiology and chronic health evaluation (APACHE) II score in surgical patients with acute renal failure (ARF) requiring dialytic support, and to assess its utility in evaluating data from this specific disease group. This was a retrospective, partly prospective follow-up study of patients who developed ARF during their course of stay on the surgical intensive care unit (ICU) of a Dutch university hospital from January 1, 1986, to January 31, 1994. A total of 111 patients were identified, of whom 104 patients were considered eligible for this study. Data for the individual APACHE II scores were calculated from the most deranged values during the initial 24 h of ICU admission (APACHE II1) and on the day dialytic support was instituted (APACHE II2). The ratio between the two APACHE II scores was also calculated for each patient (AP2/AP1 ratio). Receiver operating characteristic curves (ROC) were constructed. Other variables evaluated included age, sex, serum creatinine, diagnostic category, time from ICU admission to start of dialytic support, and the type of dialytic support. Of these 104 patients (median age 64; range 23-85 years), 51 (50%) survived to leave the ICU, of whom 47 (46%) survived to leave hospital. The APACHE II2 score (27.0 +/- 4.4 vs. 22.4 +/- 3.5; p < 0.001) and AP2/AP1 ratio (1.12 +/- 0.09 vs. 0.97 +/- 0.06; p < 0.001) were significantly higher for nonsurvivors as compared to survivors. The ROC curve was most discriminative for the AP2/AP1 ratio (area under the curve 0.92) and to a lesser extent for the APACHE II2 score (area under the curve 0.78). Estimated risk of death with the APACHE II equation did not improve predictive power. Multivariate analysis of various variables revealed the AP2/AP1 ratio as the single most important factor predicting death (odds ratio 13.8, p < 0.001). Adjusting for the AP2/AP1 ratio, no impact on outcome was observed for age, diagnostic category, time from ICU admission to start of dialytic support, and the type of dialytic support. Above a value of 1.0 of the AP2/AP1 ratio, logistic regression revealed a sharp increase in death probability with increasing AP2/AP1 ratio. APACHE II, when used at the time of initiation of dialytic support, proved to be a valid way in our surgical ICU to stratify ARF patients by the severity of their illness. Moreover, use of the AP2/AP1 ratio further improved the usefulness of this severity index and may help to identify patients who have little chance of survival. Predicting death with the APACHE II equation did not improve predictive power.