Epidemiology of acute renal failure: a prospective, multicenter, community-based study. Madrid Acute Renal Failure Study Group

Renal and respiratory failure in Scottish ICUs

The purpose of this study was to define the outcome of patients receiving both renal replacement therapy and mechanical ventilation in 16 Scottish intensive care units over a 2-year period. Patients were identified from the Scottish Intensive Care Society's database. Survivors developing end-stage renal failure were identified after examination of the Scottish Renal Registry's database. Mortality was 64.2% (392/612) for all patients receiving renal replacement therapy and mechanical ventilation. End-stage renal failure developed in 1.6% (3/188) of the survivors of acute renal failure and in 33% (4/11) of the survivors with pre-existing chronic renal failure. Mortality has not improved when compared with earlier studies. End-stage renal failure rarely develops following acute renal failure in the intensive care unit.

Pathophysiologic Features and Prevention of Human and Experimental Acute Tubular Necrosis

Abstract.Acute renal failure (ARF) remains a common and potentially devastating disorder that affects as many as 5% of all hospitalized patients, with a higher prevalence in patients in critical care units. The focus of this article is on categorizing recent pathophysiologic and clinically relevant developments in the field. The vascular and tubular factors in the pathogenesis of ARF, together with the potential mechanisms of recovery and repair of the injured kidney, are discussed. A number of experimental and clinical interventions to prevent. ARF are summarized. Although the clinical treatment of these patients is still largely supportive and many recent clinical trials showed rather negative results, it is hoped that basic research will provide therapeutic tools to improve the grim prognosis of this disease in the future.

Acute renal failure: a practical update

Acute renal failure (ARF) affects almost all medical specialties. Its occurrence seems to be increasing in hospitalized patients. A structured approach to the evaluation and management of ARF would facilitate rapid diagnosis and treatment in most patients. Appreciation for the multiple drugs that affect renal function is especially important. Exclusion of urinary outflow obstruction and administration of therapies that improve renal perfusion should be given top priority with respect to managing ARF. Dialytic intervention for ARF is required when otherwise irreversible pathophysiologic derangements of electrolyte homeostasis, fluid balance, and uremic solute control are imminent. This article provides a brief review and update on the clinical evaluation and management of ARF.

Patient survival and renal recovery in acute renal failure: randomized comparison of cellulose acetate and polysulfone membrane dialyzers

OBJECTIVE

To investigate survival and renal recovery after dialysis in patients with acute renal failure with use of synthetic membranes compared with substituted cellulose membranes.

PATIENTS AND METHODS

We prospectively studied survival and recovery of renal function of 66 patients with acute renal failure who required intermittent hemodialysis. Patients were randomized to exclusive treatment with either cellulose acetate (CA) or polysulfone (PS) hemodialysis membranes. Additionally, markers of biocompatibility (complement, leukocyte counts, cytokine concentration) were measured at initiation and 1 hour after initiation of dialysis among 10 patients equally distributed between the CA and PS groups.

RESULTS

The cohorts were indistinguishable with respect to age, sex, presence of diabetes mellitus, Acute Physiology and Chronic Health Evaluation II scores, percentage in the intensive care unit (ICU), and adequacy of dialysis. Survival (76% CA, 73% PS; P=.78) and recovery of renal function at 30 days (58% CA, 39% PS; P=.14) were not statistically different in the 2 groups. Among 26 CA patients and 27 PS patients treated in the ICU, survival was not statistically different (73% CA, 67% PS; P=.61); however, the proportion of patients recovering renal function suggested a benefit favoring CA membranes (65% CA, 37% PS; P=.04). Additionally, markers of biocompatibility were not significantly different between groups among the 10 patients equally distributed between the CA and PS groups.

CONCLUSIONS

Overall clinical outcomes among patients with acute renal failure treated with CA hemodialysis membranes and those treated with PS membranes were not significantly different. The observed advantage favoring renal recovery among this ICU population treated with CA hemodialysis membranes warrants further investigation.

Predicting patient outcome from acute renal failure comparing three general severity of illness scoring systems

BACKGROUND

A major problem of studies on acute renal failure (ARF) arises from a lack of prognostic tools able to express the medical complexity of the syndrome adequately and to predict patient outcome accurately. Our study was thus aimed at evaluating the predictive ability of three general prognostic models [version II of the Acute Physiology and Chronic Health Evaluation (APACHE II), version II of the Simplified Acute Physiology Score (SAPS II), and version II of the Mortality Probability Model at 24 hours (MPM24 II)] in a prospective, single-center cohort of patients with ARF in an intermediate nephrology care unit.

METHODS

Four hundred twenty-five patients consecutively admitted for ARF to the Nephrology and Internal Medicine Department over a five-year period were studied (272 males and 153 females, median age 71 years, interquartile range 61 to 78, median APACHE II score 23, interquartile range 18 to 28). Acute tubular necrosis (ATN) accounted for 68.7% (292 out of 425) of patients. Renal replacement therapies (hemodialysis or continuous hemofiltration) were used in 64% (272 out of 425) of ARF patients.

RESULTS

Observed mortality was 39.1% (166 out of 425). The mean predicted mortality was 36.2% with APACHE II (P = 0.571 vs. observed mortality), 39.3% with SAPS II (P = 0.232), and 45.1% with MPM24 II (P < 0.0001). Lemeshow-Hosmer goodness-of-fit C and H statistics were 15.67 (P = 0.047) and 12.05 (P = 0.15) with APACHE II, 32.53 (P = 0.0001), 39.8 (P = 0.0001) with SAPS II, 21.86 (P = 0.005), and 20. 24 (P = 0.009) with MPM24 II, respectively. Areas under the receiver operating characteristic (ROC) curve were 0.75, 0.77, and 0.85, respectively.

CONCLUSIONS

The APACHE II model was a slightly better calibrated predictor of group outcome in ARF patients, as compared with the SAPS II and MPM24 II outcome prediction models. The MPM24 II model showed the best discrimination capacity, in comparison with both APACHE II and SAPS II models, but it constantly and significantly overestimated mean predicted mortality in ARF patients. None of the models provided sufficient confidence for the prediction of outcome in individual patients. A high degree of caution must be exerted in the application of existing general prognostic models for outcome prediction in ARF patients.

A prospective, multicenter study of the epidemiology, management, and outcome of severe acute renal failure in a "closed" ICU system

The safety and effectiveness of "closed" intensive care units (ICUs) are highly controversial. The epidemiology and outcome of acute renal failure (ARF) requiring replacement therapy (severe ARF) within a "closed" ICU system are unknown. Accordingly, we performed a prospective 3-mo multicenter observational study of all Nephrology Units and ICUs in the State of Victoria (all "closed" ICUs), Australia, and focused on the epidemiology, treatment, and outcome of patients with severe ARF. We collected demographic, clinical, and outcome data using standardized case report forms. Nineteen ward patients and 116 adult ICU patients had severe ARF (13.4 cases/100, 000 adults/yr). Among the ICU patients with severe ARF, 37 had impaired baseline renal function, 91 needed ventilation, and 95 needed vasoactive drugs. Intensivists controlled patient care in all cases. Continuous renal replacement therapy (CRRT) was used in 111 of the ICU patients. Nephrological opinion was sought in only 30 cases. Predicted mortality was 59.6%. Actual mortality was 49.2%. Only 11 ICU survivors were dialysis dependent at hospital discharge. In the state of Victoria, Australia, intensivists manage severe ARF within a "closed" ICU system. Renal replacement is typically continuous and outcomes compare favorably with those predicted by illness severity scores. Our findings support the safety and efficacy of a "closed" ICU model of care.

Regional citrate anticoagulation in continuous venovenous hemodiafiltration

Over the past several years, continuous venovenous hemodiafiltration (CVVHDF) using pump-driven devices has gained wide acceptance as a form of renal replacement therapy for critically ill patients with acute renal failure. More recently, regional citrate anticoagulation has proven useful as a method of anticoagulating CVVHDF circuits, particularly in those patients at high risk for bleeding. However, an easy and convenient method for guiding the dose of citrate infusion has not previously been described. We describe the use of an algorithm using posthemofilter levels of ionized calcium to guide the dose of administered regional citrate on the survival time and urea and creatinine clearances of 24 Hospal AN69HF hemofilters. Nine patients with acute and chronic renal failure requiring CVVHDF were studied. The median filter survival time when using the postfilter ionized calcium algorithm was 3.4 days, with a survival probability of 46% (95% confidence interval [CI], 17 to 71). Random-effects linear regression analysis did not show a significant decline in blood-side urea clearance (P = 0.041) or creatinine clearance (P = 0. 308). Moreover, definite bleeding complications occurred with an incidence rate of 0.045/person-day on citrate anticoagulation (95% CI, 0.006 to 0.16), and occult bleeding occurred with an incidence rate of 0.091/person-day on citrate anticoagulation (95% CI, 0.03 to 0.23). Guiding regional citrate anticoagulation through the use of posthemofilter ionized calcium levels is a safe and effective method of prolonging filter life during CVVHDF.

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.

Diminished adenylate cyclase activity and aquaporin 2 expression in acute renal failure rats

BACKGROUND

The present study was aimed at investigating the changes of aquaporin 2 (AQP2) expression and its underlying mechanisms in ischemic acute renal failure (ARF).

METHODS

ARF was induced by clamping the both renal arteries for 60 minutes in rats. Two or seven days later, AQP2 expression and trafficking were determined in the kidney by Western blot analysis and immunohistochemistry. The activity of adenylate cyclase was also measured.

RESULTS

The urinary flow rates in ARF-2 and ARF-7 day were significantly increased in association with decreases of urine osmolality. While there was decreased expression of AQP2 in the cortex, outer medulla, and inner medulla in ARF, it was most pronounced in the outer medulla. The AQP2 expression was reduced in the apical membrane-enriched fraction as well the subapical vesicle-enriched fraction in ARF; however, the degree was greater in the former than in the latter. Immunohistochemical study also showed a markedly decreased expression of AQP2 in the collecting duct in ARF. cAMP generation in response to arginine vasopressin (AVP) in the kidney was attenuated in ARF, most prominently in the outer medulla. cAMP generation in the outer medulla in response to forskolin was not affected, but sodium fluoride was significantly blunted in ARF.

CONCLUSIONS

The AVP-stimulated adenylate cyclase activity is impaired in ARF, secondary to a defect at the level of the G protein. The expression of AQP2 was reduced as a consequence, which may in part account for urinary concentration defect in ARF.

Initial versus delayed acute renal failure in the intensive care unit. A multicenter prospective epidemiological study. Rhône-Alpes Area Study Group on Acute Renal Failure

We performed a prospective study in the 28 multidisciplinary intensive care units (ICUs) in the Rhône-Alpes area in France to investigate the role of initial versus delayed occurrence of acute renal failure (ARF) in patient outcome. ARF was defined as a serum creatinine concentration > 300 micromol/L, urine output < 500 ml/24 h (or < 180 ml/8 h), or hemodialysis requirement. Over the 1-yr study period, 1,086 patients presented with ARF on ICU admission or during the first 2 d of ICU stay (Group A; 736 patients), from Day 3 to Day 6 (Group B; 202 patients), or from Day 7 (Group C; 148 patients). The overall hospital mortality rate was 66% (61% in Group A, 71% in Group B, and 81% in Group C; p < 0.0001). Logistic regression analysis of a random sample of 510 patients showed that SAPS II score on ICU admission, number of ARF episodes, previous health status, absence of oliguria, absence of hemodialysis, and absence of ischemic acute tubular necrosis were predictive of patient survival. This model was tested and validated on the basis of the remaining patients. Thus, in this population, late ARF was not a predictive factor for patient outcome.

Etiologies and outcome of acute renal insufficiency in older adults: a renal biopsy study of 259 cases

Acute renal insufficiency is a common problem, yet one that is frequently reversible with proper diagnosis and treatment. Although it has been argued that a renal biopsy is not needed for diagnosis in most cases of acute renal failure in the elderly, other studies have shown frequent disagreements between clinical and renal biopsy diagnoses in such cases. To investigate the causes of acute renal insufficiency in patients aged at least 60 years who underwent a renal biopsy and possible correlations between biopsy findings and renal survival, we first identified all native renal biopsy specimens from patients aged 60 years or older processed at The University of Chicago Medical Center (Chicago, IL) from 1991 through 1998 and reviewed the clinical records to determine the indication for the biopsy. We then reviewed again the records of those patients who underwent biopsy because of acute renal insufficiency, recorded the primary renal biopsy diagnosis in each of these cases, and obtained follow-up information for patients who underwent biopsy before July 1996. During the study period, 1,065 of 4,264 biopsy specimens (25.0%) received were obtained from patients aged 60 years or older, and acute renal insufficiency was the indication for biopsy in 259 of these patients (24.3%). The most frequent primary diagnoses on these latter biopsy specimens were pauci-immune crescentic glomerulonephritis (GN) with or without arteritis, 31.2% of biopsy specimens; acute interstitial nephritis, 18.6%; acute tubular necrosis (ATN) with nephrotic syndrome, 7.5%; atheroemboli, 7.1%; ATN alone, 6.7%; light chain cast nephropathy (LCCN), 5.9%; postinfectious GN, 5.5%; anti-glomerular basement membrane antibody nephritis, 4.0%; and immunoglobulin A (IgA) nephropathy and/or Henoch-Schönlein nephritis, 3.6%. Eight biopsy specimens (3.2%) showed only benign nephrosclerosis without an apparent cause of acute renal insufficiency, and another six specimens were inadequate. The renal biopsy diagnosis was in agreement with the prebiopsy clinical diagnosis (or differential diagnosis) in 107 of the 161 cases (67%) in which such information was provided. The distribution of diagnoses was similar in patients in the age groups of 60 to 69, 70 to 79, and 80 years or older, although younger age correlated significantly with improved renal and patient survival. The relative risk for progression to end-stage renal disease (ESRD) also increased according to diagnostic categories: LCCN (greatest risk) > GN other than pauci-immune > atheroemboli congruent with pauci-immune crescentic GN > tubulointerstitial diseases other than LCCN (the latter category including ATN with nephrotic syndrome). Development of ESRD correlated significantly with decreased patient survival. In summary, renal biopsy in patients aged 60 years or older with acute renal insufficiency uncovered the cause in greater than 90% of the cases and provided clinically useful information with respect to expectation for renal survival and potential treatment options.

Treatment-related acute renal failure in the elderly: a hospital-based prospective study

BACKGROUND

Elderly individuals need a host of diagnostic procedures and therapeutic interventions to take care of ailments. This prospective study was carried out to determine the magnitude of treatment-related acute renal failure (ARF) in the elderly in a hospital setting, to know about pathogenetic factors and to study the factors that could predict an adverse outcome.

METHODS

All elderly patients (>60 years) admitted over a 12-month period were screened prospectively throughout their hospital stay for the development of ARF.

RESULTS

Of 31860 patients admitted, 4176 (13%) were elderly. Of these 59 (1.4%) developed ARF in the hospital. Nephrotoxic drugs contributed towards development of ARF in 39 (66%), sepsis and hypoperfusion in 27 (45.7%) each, contrast medium in 10 (16.9%) and postoperative ARF occurred in 15 (25.4%) patients. These pathogenetic factors were responsible for ARF in different combinations. Amongst these combination of pathogenetic factors, radiocontrast administration (partial chi(2) 28.1, P<0.0001), surgery (partial chi(2) 14.89, P=0.001), and drugs (partial chi(2) 6. 22, P=0.0126) predicted ARF on their own. Nine patients (15.23%) needed dialytic support. Of 59 patients, 15 (25.4%) died, of those who survived, 38 (86.3%) recovered renal function completely and six (13.6%) partially. Mortality in the elderly with ARF was significantly higher than in those without ARF (25.4 vs 12.5%; chi(2) 8.3, P=0.03). Sepsis (odds ratio 43), oliguria (odds ratio 64), and hypotension (odds ratio 15) were independent predictors of poor patient outcome on logistic regression analysis.

CONCLUSION

Incidence of treatment-related ARF in the elderly was 1.4%, with more than one pathogenetic factor playing a role in the development of ARF in the majority. Sepsis, hypotension, and oliguria were the independent predictors of poor patient outcome.

Comparison of cellulose diacetate and polysulfone membranes in the outcome of acute renal failure. A prospective randomized study

BACKGROUND

Whether the nature of haemodialysis (HD) membranes can influence the outcome of acute renal failure (ARF) remains debatable. Recent studies have suggested that dialysis with bioincompatible unsubstituted cellulosic membranes is associated with a less favourable patient outcome than dialysis with biocompatible synthetic membranes. Since we generally use a modified cellulosic membrane with substantially lower complement- and leukocyte-activating potential than cuprophane, for dialysis of patients with ARF, and because there are no data in the literature regarding the influence of modified cellulosic membranes on the outcome of patients with ARF, we compared the outcome of ARF patients dialysed either with cellulose diacetate or with a synthetic polysulfone membrane. We also investigated the potential role of permeability by comparing membranes with high-flux versus low-flux characteristics.

METHODS

This prospective, randomized, single centre study included 159 patients with ARF requiring HD. Patients were stratified according to age, gender, and APACHE II score and then randomized in chronological order to one of three dialysis membranes: low-flux polysulfone, high-flux polysulfone and meltspun cellulose diacetate.

RESULTS

Aetiologies of ARF and the prevalence of oliguria were similarly distributed among the three groups. There was no significant difference between the three groups for survival (multivariate Cox's proportional hazards model, P=0.57), time necessary to recover renal function (P=0.82), and number of dialysis sessions required before recovery (P=0.86). Multivariate analysis showed that survival was significantly influenced only by the severity of the disease state (APACHE III score, P<0.0001), but not by the nature of the dialysis membrane (P=0.57) or the presence of oliguria (P=0.24).

CONCLUSIONS

Among patients with ARF requiring HD survival and recovery time are not significantly influenced by the use of either meltspun cellulose diacetate or the more biocompatible high-flux or low-flux polysulfone. Dialysis using modified cellulose membranes is just as effective as dialysis using synthetic polysulfone membranes, but at a lower cost. In addition, the flux of the membrane did not influence patient outcome.

Chronic reduction in renal mass in the rat attenuates ischemia/reperfusion injury and does not impair tubular regeneration

It is not known whether a kidney with chronic structural and functional changes is more vulnerable to an acute renal insult, and whether its regeneration capacity after injury is altered. To study this question, Lewis rats were submitted 10 wk after 5/6 nephrectomy to an ischemic insult of 60 min (remnant kidney [RK] group). Functional and morphologic data of the RK group were compared with data obtained in 10-wk uninephrectomized (1K) and normal (2K) Lewis rats with unilateral and bilateral renal ischemia, respectively. The acute postischemic decrease in creatinine clearance was smallest in the RK group, followed by the 2K and 1K groups, respectively. At days 1 and 3, fewer proximal tubules in the outer stripe of the outer medulla of the RK and 2K groups had undergone acute tubular necrosis compared with the 1K group. The mean percentage of tubules with signs of regeneration was maximal at day 3 in the three experimental groups. At day 10, regeneration was almost complete in the three groups. The number of leukocytes (OX1+ cells) present in the RK before ischemia did not increase after ischemia/reperfusion injury (377 +/- 146 cells/mm2 at day 0) in contrast to the 1K and 2K groups. In the latter groups, the number of leukocytes had increased gradually, reaching a maximum at day 15 (1K: 960 +/- 308 cells/mm2) and day 10 (2K: 668 +/- 164 cells/mm2), respectively. In conclusion, this study has shown that an RK exhibiting chronic morphologic changes of interstitial fibrosis and tubular atrophy is protected against ischemia/reperfusion injury, and that its regeneration capacity is preserved. The reperfusion injury is not followed by further accumulation of leukocytes, which were already present in the RK before ischemia.

Haemodialysis-membrane biocompatibility and mortality of patients with dialysis-dependent acute renal failure: a prospective randomised multicentre trial. International Multicentre Study Group

BACKGROUND

There is controversy as to whether haemodialysis-membrane biocompatibility (ie, the potential to activate complement and neutrophils) influences mortality of patients with acute renal failure. We did a prospective randomised multicentre trial in patients with dialysis-dependent acute renal failure treated with two different types of low-flux membrane.

METHODS

180 patients with acute renal failure were randomly assigned bioincompatible Cuprophan (n=90) or polymethyl-methacrylate (n=90) membranes. The main outcome was survival 14 days after the end of therapy (treatment success). Odds ratios for survival were calculated and the two groups were compared by Fisher's exact test. Analyses were based on patients treated according to protocol (76 Cuprophan, 84 polymethyl methacrylate).

FINDINGS

At the start of dialysis, the groups did not differ significantly in age, sex, severity of illness (as calculated by APACHE II scores), prevalence of oliguria, or biochemical measures of acute renal failure. 44 patients (58% [95% CI 46-69]) assigned Cuprophan membranes and 50 patients (60% [48-70]) assigned polymethyl-methacrylate membranes survived. The odds ratio for treatment failure on Cuprophan compared with polymethyl-methacrylate membranes was 1.07 (0.54-2.11; p=0.87). No difference between Cuprophan and polymethyl-methacrylate membranes was detected when the analysis was adjusted for age and APACHE II score. 18 patients in the Cuprophan group and 20 in the polymethyl-methacrylate group had clinical complications of therapy (mainly hypotension).

INTERPRETATION

There were no differences in outcome for patients with dialysis-dependent acute renal failure between those treated with Cuprophan membranes and those treated with polymethyl-methacrylate membranes.

Comparing continuous hemofiltration with hemodialysis in patients with severe acute renal failure

Continuous venovenous hemofiltration (CVVH) or CVVH with additional diffusive dialysis (CVVH-D) has theoretical advantages in treating severe acute renal failure (ARF), but no prospective clinical trials or restrospective comparison studies have clearly shown its superiority over intermittent hemodialysis (HD). To evaluate this question, all 349 adult patients with ARF receiving renal replacement therapy (RRT) at our medical center during 1995 and 1996 were analyzed using multivariate Cox proportional hazards methods. Initial univariate analysis showed the odds of death when receiving initial CVVH to be more than twice those when receiving initial HD (risk for death, 2.03; P < 0.01). Progressive exclusion of patients in whom the RRT modality might not be open to choice and the risk for death was very high (systolic blood pressure < 90 mm Hg; total bilirubin level > 15 mg/dL; or total RRT < 48 hours) for total RRT left 227 patients in whom the risk for death was 1.09 (95% confidence interval [CI], 0.67 to 1.80; P = 0.72) for initial CVVH, virtually equivalent to the risk for initial HD. Comorbid indicators significantly associated with death or failure to recover renal function included: older age; medical rather than surgical diagnosis; preexisting infection or trauma and liver disease as primary diagnoses; and abnormal bilirubin level or vital signs at initiation of RRT. These results show that the high crude mortality rate of patients undergoing CVVH was related to severity of illness and not the treatment choice itself. With the addition of more inclusive comorbidity data and a broader spectrum of interim outcomes, this type of analysis is a practical alternative to what would almost assuredly be a cumbersome and costly prospective, controlled trial comparing traditional HD with CVVH.

Role of hypoalbuminemia and hypocholesterolemia as copredictors of mortality in acute renal failure

Role of hypoalbuminemia and hypocholesterolemia as co-predictors of mortality in acute renal failure.

BACKGROUND

Hypoalbuminemia (LA) and hypocholesterolemia (LC) have been reported to portend high mortality in both older patients and in patients with end-stage renal disease. Even though low levels have been reported in critically ill patients, they have not been clearly defined as predictors of mortality in acute renal failure (ARF). The impact of LA and LC on mortality in ARF is evaluated in this study.

METHODS

We conducted a computer-assisted three-year retrospective review of all cases of de novo ARF seen at an inner city tertiary-care facility. One hundred cases met the criteria for inclusion in the study. We employed both univariate and multivariate logistic regression models to estimate the relative risks (RR) and 95% confidence intervals (CI) of mortality associated with several variables.

RESULTS

Predictors associated with a high risk of death identified in this study include LC < or = 150 mg/dl (< or = 3.9 mmol/liter; RR, 7.4; CI, 2.7 to 20.3), LA < or =35 g/liter (RR, 5.0; CI, 1.9 to 13.2), sepsis (RR, 9.4; CI, 3.7 to 23.9), mechanical ventilation (RR, 10.8; CI, 2.8 to 41.0), oliguria (RR 17.0; CI, 6.2 to 46.6), and multisystem organ failure (RR 24.7; CI, 10.3 to 59.1). The overall gross mortality was 39%, but mortality among intensive care unit patients was 82%. Survival was 82% among patients with serum albumin >35 g/liter versus 48% among those with serum albumin < or =35 g/liter (chi2 = 11.9, P = 0.0006). Similarly, survival was higher among patients with cholesterol >150 mg/dl (>3.9 mmol/liter) than those whose levels were < or =150 mg/dl (< or =3.9 mmol/liter; 85 vs. 44%, ch 17.3, P<0.0001). Significant association between LA and LC was observed (R = 0.4, P<0.0001). Age, gender, level of plasma creatinine, and underlying chronic medical conditions were not predictive of mortality.

CONCLUSION

Survival in ARF is significantly altered by the levels of albumin and cholesterol. Because both LC and LA can be cytokine mediated, their presence in ARF should be considered ominous.

Acute renal failure in the cardiac care unit: etiologies, outcomes, and prognostic factors

BACKGROUND

Heart disease is a leading cause of hospitalizations, and its prevalence is expected to grow rapidly over the next few decades. The purpose of this study was to examine the incidence, etiologies, outcomes, and risk factors for mortality of acute renal failure (ARF) in cardiac care unit (CCU) patients.

METHODS

A retrospective, cohort study examining all patients who developed ARF while in the CCU at Barnes-Jewish Hospital over a 17-month time period was performed. Charts were reviewed to determine etiologies, hospital mortality rates, and risk factors for mortality.

RESULTS

Four percent of admissions to the CCU met criteria for ARF while in the unit. The etiologies of ARF were congestive heart failure (CHF; 35%), multifactorial (usually involving CHF; 26%), arrest/arrhythmia (13%), contrast (11%), volume depletion (6%), sepsis (6%) and obstruction (3%). The mortality rate was 50%. Oliguria, mechanical ventilation, and decreased cardiac function were statistically significant risk factors for mortality by univariate but not multivariate analysis. Thirty percent of patients with a cardiac index of less than 2.0 liter/min/m2 survived to discharge.

CONCLUSIONS

ARF occurs commonly in CCU patients and is associated with a high mortality rate. However, there are a significant number of survivors even among patients with severely depressed cardiac function.

Prevalence and clinical outcome associated with preexisting malnutrition in acute renal failure: a prospective cohort study

Malnutrition is a frequent finding in hospitalized patients and is associated with an increased risk of subsequent in-hospital morbidity and mortality. Both prevalence and prognostic relevance of preexisting malnutrition in patients referred to nephrology wards for acute renal failure (ARF) are still unknown. This study tests the hypothesis that malnutrition is frequent in such clinical setting, and is associated with excess in-hospital morbidity and mortality. A prospective cohort of 309 patients admitted to a renal intermediate care unit during a 42-mo period with ARF diagnosis was studied. Patients with malnutrition were identified at admission by the Subjective Global Assessment of nutritional status method (SGA); nutritional status was also evaluated by anthropometric, biochemical, and immunologic parameters. Outcome measures included in-hospital mortality and morbidity, and use of health care resources. In-hospital mortality was 39% (120 of 309); renal replacement therapies (hemodialysis or continuous hemofiltration) were performed in 67% of patients (206 of 309); APACHE II score was 23.1+/-8.2 (range, 10 to 52). Severe malnutrition by SGA was found in 42% of patients with ARF; anthropometric, biochemical, and immunologic nutritional indexes were significantly reduced in this group compared with patients with normal nutritional status. Severely malnourished patients, as compared to patients with normal nutritional status, had significantly increased morbidity for sepsis (odds ratio [OR] 2.88; 95% confidence interval [CI], 1.53 to 5.42, P < 0.001), septic shock (OR 4.05; 95% CI, 1.46 to 11.28, P < 0.01), hemorrhage (OR 2.98; 95% CI, 1.45 to 6.13, P < 0.01), intestinal occlusion (OR 5.57; 95% CI, 1.57 to 19.74, P < 0.01), cardiac dysrhythmia (OR 2.29; 95% CI, 1.36 to 3.85, P < 0.01), cardiogenic shock (OR 4.39; 95% CI, 1.83 to 10.55, P < .001), and acute respiratory failure with mechanical ventilation need (OR 3.35; 95% CI, 3.35 to 8.74, P < 0.05). Hospital length of stay was significantly increased (P < 0.01), and the presence of severe malnutrition was associated with a significant increase of in-hospital mortality (OR 7.21; 95% CI, 4.08 to 12.73, P < 0.001). Preexisting malnutrition was a statistically significant, independent predictor of in-hospital mortality at multivariable logistic regression analysis both with comorbidities (OR 2.02; 95% CI, 1.50 to 2.71, P < 0.001), and with comorbidities and complications (OR 2.12; 95% CI, 1.61 to 2.89, P < 0.001). Malnutrition is highly prevalent among ARF patients and increases the likelihood of in-hospital death, complications, and use of health care resources.

Therapeutic use of the natriuretic peptide ularitide in acute renal failure

BACKGROUND

Ularitide is a member of the natriuretic peptide family. This hormone exhibits an N-terminal extension by four amino acids compared with atrial natriuretic peptide. Ularitide was shown to exert strong diuretic and natriuretic effects when infused intravenously. Its main action sites are the glomerulum, inducing preglomerular vasodilation and postglomerular vasoconstriction and thereby elevating the glomerular filtration rate, and the tubular system inhibiting Na(+)-reabsorption. In initial uncontrolled clinical trials, this peptide was shown to have beneficial effects in patients suffering from oliguric acute renal failure.

METHODS

We conducted a double-blind, placebo-controlled, multicenter, dose-finding trial recruiting 176 patients randomized into 4 different Ularitide doses groups (U5, U20, U40, and U80 ng/kg/min) and a placebo group (U0). Ularitide/placebo infusion was performed for 5 days with half the originally infused dose on day 5. The primary objective of the study was to test various doses of Ularitide in patients suffering from oliguric acute renal failure to avoid mechanical renal replacement therapy during the first 12 hours.

FINDINGS

The results indicate that Ularitide does not reduce the incidence of mechanical renal replacement therapy compared with placebo-treated patients during the first 12 h of treatment (U0: 36 (20), U5: 35 (11), U20: 36 (9), U40: 28 (8), U80: 41 (12), (% (n) (p = 0.87)). Diuresis increased in the Ularitide-treated groups and the placebo group after onset of infusion and did not show any significant difference in the first 12 h collection period (U0: 576, U5: 514, U20: 500, U40: 360, U80: 158 ML/12h (Median), (p = 0.16)).

INTERPRETATION

In summary, the incidence of mechanical renal replacement therapy in critically ill patients suffering from oliguric acute renal failure could not be altered positively by Ularitide administration according to our protocol. Further prospective clinical trials are needed to answer the question whether a different patient collective or a prophylactic administration of Ularitide are more promising approaches in the clinical setting of oliguric acute renal failure.

Treatment of acute renal failure

Acute renal failure is a life threatening illness whose mortality has remained high since the introduction of hemodialysis 25 years ago, despite advances in supportive care. Acute renal failure is an extremely morbid and costly disorder with a significant proportion of patients progressing to end-stage renal disease requiring dialysis. To the nephrologist, acute renal failure remains an extremely frustrating disease, because the pathophysiology is not well understood and the limited therapeutic options force the nephrologist to sit on the sidelines and wait for renal function to return. For example, dialysis remains the only FDA-approved treatment for acute renal failure, but dialysis may also cause renal injury that prolongs renal failure. The purpose of this perspective is to understand the results of the recent, largely negative, clinical trials in view of recent advances in the epidemiology of ARF. This review will also discuss diagnostic tools, strategies for improved design of clinical trials, and other therapeutic interventions that will be needed to properly treat acute renal failure in the 21st century.

Delayed graft function does not reduce the survival of renal transplant allografts

BACKGROUND

The aim of the present study was to investigate the effect of delayed graft function (DGF) in graft outcome when adjusted by the presence of acute rejection in the first month after transplantation.

METHODS

A total of 437 cadaveric renal transplant patients on cyclosporine and steroids were included in the study. Variables related to donor, recipient, and graft were prospectively collected.

RESULTS

The incidence of DGF was 44.4%. When patients dying with a functioning graft were censored, graft survival rates at 1 and 6 years were similar in patients with immediate function to those with DGF, when rejection was not present (96% and 81% vs. 95% and 83%, respectively). Rejection negatively influenced graft survival rates at 1 and 6 years, both in patients with immediate graft function (80% and 73%, P<0.05 vs. no DGF/no rejection) and more deeply in those with associated DGF (77% and 62%, P<0.001 vs. no DGF/no rejection). Rejection was more frequently diagnosed in patients with DGF than in those with immediate graft function (50% vs. 39.9%, P<0.05). Length of hospitalization was longer and the number of needle core biopsies was higher in patients with DGF or rejection. The presence of both complications had an additive effect.

CONCLUSIONS

This study showed that DGF did not adversely affect kidney graft survival in patients without rejection. However, it increased the length of hospitalization and the number of graft biopsies, thus increasing the cost of transplantation. Moreover, rejection was more frequent in patients with DGF, and it had a negative impact on graft outcome. Because the association of DGF and rejection gave the poorest outcome, an effort should be made to prevent both complications.

Causes and prognosis of acute renal failure in the very old. Madrid Acute Renal Failure Study Group

OBJECTIVES

There is a tendency to treat older people with Acute Renal Failure (ARF) less aggressively because of the presumed less acceptable end results. This has not been proved, and their prognosis may be similar to that found in the younger population. There are no studies on the incidence, causes, and evolution of ARF in patients 80 years of age and older.

DESIGN

A multicenter, prospective, longitudinal study.

SETTING

The 13 hospitals with nephrology units that serve the 4.2 million people in Madrid, Spain.

MEASUREMENTS

A number of demographic, clinical, and therapeutic variables were studied in each case.

RESULTS

One hundred three episodes of ARF occurred in patients 80 years of age and older (Group 1), 256 in patients aged 65 to 79 years (Group 2), and 389 in people younger than age 65 (Group 3). Acute tubular necrosis was diagnosed in 39% of cases in Group 1, in 48% in Group 2, and in 55% in Group 3 (P = .004, 1 vs 3); prerenal ARF was diagnosed in 30%, 28%, and 21% (P = .054, 1 vs 3) and obstructive ARF in 20%, 11%, and 7% (P < .001, 1 vs 3) of cases, respectively. Serum creatinine at admission, peak values, values at discharge or death, duration of both admission and ARF episode, and mortality were similar in all groups. In stratified analysis, relative risk for mortality in patients aged more than 80 years was 1.09 [95%CI 0.86,1.36 (P = .562)], and in those aged 65 to 79 it was 0.99 [95%CI 0.83,1.18 (P = .954)] compared with patients aged less than 65 years. Risk of death was also similar when only acute tubular necrosis cases were considered. Sustained hypotension was associated with higher mortality (44% of nonsurviving older persons vs 9% of survivors, P < .001).

CONCLUSION

Age is not a particularly poor prognostic sign, and outcome seems to be within acceptable limits for very old patients with ARF. Acute dialysis should not be withheld from patients solely because they are more than 80 years of age.