Survial from acute renal failure with and without multiple organ dysfunction

Acute Renal Failure in Critically Ill Patients

Acute renal failure is an important cause of morbidity in critically ill patients. Acute renal failure results from pre renal and postrenal causes and, most importantly, acute tubular necrosis (ATN). Although it is known that renal toxins and renal ischemia are the most common causes of ATN in hospitalized patients, the exact pathogenesis of this entity is still not fully understood. Patients in the intensive care unit are at high risk for ATN because of hemodynamic instability, the administration of neph rotoxic antibiotics or chemotherapeutic agents, and ex posure to radiographic contrast agents. The acquired immunodeficiency syndrome is also associated with an increased risk of renal failure development, either from complications of the disease itself or from its treatment. Many consequences of acute renal failure such as vol ume overload, acidosis, hyperkalemia, and serositis can be managed adequately with peritoneal dialysis, hemo dialysis, or a newer technique, continuous arteriove nous hemofiltration. Despite improvements in treat ment, however, the mortality of ATN remains high. In this review, we recommend measures to prevent ATN in certain clinical situations that commonly occur among critically ill patients. We also review therapeutic options for treating patients in whom acute renal failure devel ops and discuss newer developments that may begin to reduce the excessive morbidity associated with ATN.

Acute kidney injury: controversies revisited

This paper addresses the epidemiology of AKI specifically in relation to recent changes in AKI classification and revisits the controversies regarding the timing of initiation of dialysis and the use of peritoneal dialysis as a renal replacement therapy for AKI. In summary, the new RIFLE/AKIN classifications of AKI have facilitated more uniform diagnosis of AKI and clinically significant risk stratification. Regardless, the issue of timing of dialysis initiation still remains unanswered and warrants further examination. Furthermore, peritoneal dialysis as a treatment modality for AKI remains underutilised in spite of potential beneficial effects. Future research should be directed at identifying early reliable biomarkers of AKI, which in conjunction with RIFLE/AKIN classifications of AKI could facilitate well-designed large randomised controlled trials of early versus late initiation of dialysis in AKI. In addition, further studies of peritoneal dialysis in AKI addressing dialysis dose and associated complications are required for this therapy to be accepted more widely by clinicians.

Incidence, risk factors and prognostic factors of acute renal failure in patients admitted to an intensive care unit

The objective of the present study was to assess the incidence, risk factors and outcome of patients who develop acute renal failure (ARF) in intensive care units. In this prospective observational study, 221 patients with a 48-h minimum stay, 18-year-old minimum age and absence of overt acute or chronic renal failure were included. Exclusion criteria were organ donors and renal transplantation patients. ARF was defined as a creatinine level above 1.5 mg/dL. Statistics were performed using Pearsons' chi2 test, Student t-test, and Wilcoxon test. Multivariate analysis was run using all variables with P < 0.1 in the univariate analysis. ARF developed in 19.0% of the patients, with 76.19% resulting in death. Main risk factors (univariate analysis) were: higher intra-operative hydration and bleeding, higher death risk by APACHE II score, logist organ dysfunction system on the first day, mechanical ventilation, shock due to systemic inflammatory response syndrome (SIRS)/sepsis, noradrenaline use, and plasma creatinine and urea levels on admission. Heart rate on admission (OR = 1.023 (1.002-1.044)), male gender (OR = 4.275 (1.340-13642)), shock due to SIRS/sepsis (OR = 8.590 (2.710-27.229)), higher intra-operative hydration (OR = 1.002 (1.000-1004)), and plasma urea on admission (OR = 1.012 (0.980-1044)) remained significant (multivariate analysis). The mortality risk factors (univariate analysis) were shock due to SIRS/sepsis, mechanical ventilation, blood stream infection, potassium and bicarbonate levels. Only potassium levels remained significant (P = 0.037). In conclusion, ARF has a high incidence, morbidity and mortality when it occurs in intensive care unit. There is a very close association with hemodynamic status and multiple organ dysfunction.

Has mortality from acute renal failure decreased? A systematic review of the literature

PURPOSE

To determine mortality rates in patients with acute renal failure during the past decades.

METHODS

We performed a MEDLINE search using the keywords "acute renal failure" crossed with "outcome," "mortality," "ICU," "critically ill" or "prognosis" in the period from January 1970 to December 2004. Abstracts and full articles were eligible if mortality rates were reported. We also reviewed the bibliographies of available studies for further potentially eligible studies. The dates of the observation period for each study and not the publication dates were considered for the analysis, so the earliest data were from 1956.

RESULTS

Of 85 articles fulfilling the criteria, 5 were excluded because of duplicate publications using the same database, so that 80 were included in our review with a total of 15897 patients. Mortality rates in most studies exceeded 30%, and there was no consistent change over time.

CONCLUSION

Despite technical progress in the management of acute renal failure over the last 50 years, mortality rates seem to have remained unchanged at around 50%.

Extended daily dialysis: A new approach to renal replacement for acute renal failure in the intensive care unit

Continuous venovenous hemofiltration (CVVH) is an effective form of renal replacement therapy for acute renal failure (ARF) that offers greater hemodynamic stability and better volume control than conventional hemodialysis in the critically ill, hypotensive patient. However, the application of CVVH in the intensive care unit (ICU) has several disadvantages, including intensive nursing requirements, continuous anticoagulation, patient immobility, and expense. We describe a new approach to the treatment of ARF in the ICU, which we have termed extended daily dialysis (EDD). In this study, EDD was compared with CVVH in 42 patients: 25 patients were treated with EDD for a total of 367 treatment days, and 17 patients were treated with CVVH for a total of 113 days. Median treatment time per day was 7.5 hours for EDD (range, 6 to 8 hours, 25th to 75th percentile) versus 19.5 hours for CVVH (range, 13.4 to 24 hours; P < 0.001). Mean arterial blood pressures (MAPs) did not differ significantly for patients treated with EDD when measured predialysis (median MAP, 70 versus 67 mm Hg for CVVH; P = 0.078), midway through daily treatment (70 versus 68 mm Hg for CVVH; P = 0.083), or at the end of treatment (71 versus 69 mm Hg for CVVH; P = 0.07). Net daily ultrafiltration was similar for the two treatment modalities (EDD, median, 3,000 mL/d; range, 1,763 to 4,445 mL/d; CVVH, 3,028 mL/d; range, 1,785 to 4,707 mL/d; P = 0.514). Anticoagulation requirements were significantly less for patients treated with EDD (median dose of heparin, 4,000 U/d; range, 0 to 5,800 U/d versus 21,100 U/d; range, 8,825 to 31,275 U/d for patients treated with CVVH; P < 0.001). We found that EDD eliminated the need for constant supervision of the dialysis machine by a subspecialty dialysis nurse, allowing one nurse to manage more than one treatment. Overall, EDD was well tolerated by the majority of patients, offered many of the same benefits provided by CVVH, and was technically easier to perform.

Prognosis in acute renal failure of septic origin: a multivariate analysis

The goal of the present study was to identify variables associated with the outcome of patients with acute renal failure (ARF) of septic origin, using multivariate analysis. The records of 168 patients were reviewed retrospectively and a crude mortality of 74% was found. Both univariate as well as multivariate analysis demonstrated an association between mortality and variables which depended on patient related factors. These included age over 60 years and several underlying diseases such as pneumonia, peritonitis, and organ dysfunction. Only one variable (late oliguria) related to the ARF itself. Thus, outcome seems related to underlying disease more than to severity of ARF.

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

There are very limited data on overall epidemiology of ARF. It is crucial to know the incidence, etiology and clinical feature of ARF to promote prevention strategies and to implement adequate resources for the management of this entity. During a nine month period, a collaborative prospective protocol with 98 variables was developed to assess all ARF episodes encountered in the 13 tertiary-care hospitals in Madrid, Spain (covering 4.2 million people of over 14 years of age). ARF was considered when a sudden rise in serum creatinine concentration (SCr) to more than 177 mumol/liter was found in patients with normal renal function, or when the sudden rise (50% or more) was observed in patients with previous mild-to-moderate chronic renal failure (SCr < 264 mumol/liter). Of the 748 cases of ARF studied, 665 episodes presented in inhabitants from the Madrid area. This gives an overall incidence of ARF of 209 cases per million population (p.m.p.; 95% CJ 195 to 223). The incidence of acute tubular necrosis (ATN) was 88 cases p.m.p. (95% CI 79 to 97), prerenal ARF 46 p.m.p (95% CI 40 to 52), acute-onset chronic ARF 29 p.m.p. (95% CI 24 to 34), and obstructive ARF 23 p.m.p. (95% CI 19 to 27). The mean age was 63 +/- 17 years. The most frequent causes of ARF were ATN (45%), prerenal (21%), acute-onset chronic renal failure (12.7%) and obstructive ARF (10%). Renal function was normal at admission in 48% of patients who later developed ARF. Mortality (45%) was much higher than that of the other patients admitted (5.4%, P < 0.001). This real outcome correlated extremely well with the expected outcome calculated through out the severity index of ARF (SI) 0.433 +/- 0.246 (mean +/- SD). In 187 cases, mortality was attributed to underlying disease, thus corrected mortality due to ARF was 26.7%. Dialysis was required in 36% of patients, and was associated with a significantly higher SI of ARF (0.57 +/- 0.23 vs. 0.35 +/- 0.19, P < 0.001) and mortality (65.9 vs. 33.2%, P < 0.001). Mortality in patients hemodialyzed with biocompatible synthetic membranes (N = 50) was similar to that observed with cellulosic ones (N = 84; 66% vs. 59.5%, NS). Mortality was higher in patients with coma, assisted respiration, hypotension, jaundice (all P < 0.001) and oliguria (P < 0.02). This study gives, for the first time, the incidence of all forms of ARF in a developed country. ARF is iatrogenically induced at a high rate by modern medicine. Prevention strategies, particularly in the perioperative period, are needed to decrease its impact.

Management of acute renal failure: new perspectives

Despite major developments in medicine, surgery, and intensive care, acute renal failure (ARF) still remains a common problem affecting approximately 5% of all general hospital patients. Mortality of all forms of ARF continues to be greater than 50%, and this percentage has not decreased significantly over the last 30 years. There are multiple factors, which may explain the persistence of such high mortality; the most important of these is probably the evolution of the disease spectrum underlying the development of ARF. At present, ARF is more often observed in older or more complex patients frequently in association with multiorgan system failure. The annual cost of managing ARF is staggering. This article reviews several of the new strategies and approaches that have been developed to aid in the management and prevention of ARF. For example, the use of biocompatible membranes has been proven to positively influence the course of ARF, which necessitates renal replacement therapy. Although continuous renal replacement therapy has a theoretical advantage compared with intermittent hemodialysis in critically ill and hemodynamically unstable patients, there are no well-controlled clinical studies to support a beneficial effect on mortality. There is, however, good evidence that calcium channel blockers play a positive role in the management of ARF, especially that associated with cadaveric kidney transplantation. Vasoactive agents, such as dopamine, may have the advantage of increasing the urine output in patients with oliguric ARF; however, their efficacy in otherwise altering the course of ARF is not well substantiated. Finally, growth factors and atrial natriuretic peptide appear to have the potential for accelerating renal recovery and decreasing morbidity and mortality from this commonly encountered medical problem. Prospective randomized clinical studies are the key to many of the dilemmas encountered with ARF.

[Severity scores underestimate the seriousness of acute renal failure after emergency surgery]

OBJECTIVES

The predictive value of APACHE II and SAPS severity scores were evaluated in a group of patients with acute renal failure admitted in ICU after emergency surgery. The criteria of poor prognosis identified in the 24 hours following admission were also evaluated.

STUDY DESIGN

Open prospective study.

PATIENTS AND METHODS

During 22 months, we included every patient admitted in ICU after emergency surgery with a serum creatinine concentration > or = 130 mumol.L-1. Clinical and biological parameters were collected in the first 24 hours following admission and the severity scores were calculated. Prediction of hospital outcome, based on APACHE II score, was calculated. The standard mortality ratio (observed mortality/predicted mortality) was calculated. Accuracy of SAPS and APACHE II score was compared using ROC curves and comparison of the areas under the curves.

RESULTS

Death in ICU occurred in 44% of the patients while hospital mortality was 51%. The standard mortality ratio for APACHE II score was 1.35. The areas under the curves for SAPS and APACHE II scores were not statistically different. The criteria of poor prognosis, identified in the first 24 hours following admission, were cardiovascular failure, oliguria and sepsis.

CONCLUSION

Conventional severity scores are inaccurate for prediction of mortality in patients with acute renal failure following emergency surgery.

Ischemic acute renal failure

Underperfusion of the kidneys often results in the development of ischemic acute renal failure. This review summarizes the recent developments in the understanding of the pathophysiology, diagnosis, and treatment of this serious and costly disorder that affects almost 5% of hospitalized patients.

Continuous venovenous hemofiltration: an alternative to continuous arteriovenous hemofiltration and hemodiafiltration in acute renal failure

Continuous venovenous hemofiltration (CVVH) has been used as an alternative to continuous arteriovenous hemofiltration (CAVH) and hemodiafiltration (CAVHD) in the management of critically ill patients with acute renal failure. This report describes our experience with the first 25 patients treated with CVVH at our institution. Vascular access was obtained through a single dual-lumen venous catheter. A blood pump was used to provide ultrafiltration pressure. An ultrafiltrate pump was incorporated to ensure predictable ultrafiltrate production rates. Safety features in the extracorporeal circuit included a venous drip chamber with bubble detector and an in-line pressure monitor. CVVH was initiated by a nephrologist and dialysis nurse and was maintained by the intensive care unit (ICU) nursing staff. Fifteen females and 10 males received CVVH therapy for a total of 193.5 days (average, 7.7 +/- 10.3 days; range, 0.5 to 48 days). Four of the 25 patients (16%) survived and were discharged from the hospital. Four additional patients (16%) survived the acute phase of their illness, but died from complications of their primary disease before discharge from the hospital. The mean weight change during CVVH was -7.9 +/- 7.0 kg (range, -26.5 to +2.9 kg). Metabolic waste products and electrolytes were adequately controlled by CVVH in all but one hypercatabolic patient. The mean heparin dose required was 6.5 +/- 4.2 U/kg/h and was adjusted to prevent filter clotting rather than to achieve a predetermined activated partial thromboplastin time (PTT). The median PTT was 35.8 seconds (range, 22.0 to 100; control, 19.5 to 29.5 seconds). Four episodes of volume-responsive hypotension occurred during the 193.5 treatment days. Only one patient experienced a hemorrhagic complication during CVVH. No patient experienced a complication related to vascular access. Twelve of 111 total hemofilters were changed because of clot formation. CVVH was well tolerated by patients and managed efficiently by the ICU nursing staff.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute renal failure associated with haematological malignancies: a review of 10 years experience

Patients with ARF and haematological malignancy (excluding myeloma), presenting to a single unit over 10 years were analyzed to see if patients likely to benefit from intensive renal supportive therapy could be identified. 31 episodes of ARF were identified in 29 patients (mean age 51 +/- 2.9 yr): 19 were associated with acute leukaemia (13 AML, 6 ALL); 10 with lymphoma. Acute tubular necrosis (ATN) was identified as the cause of ARF in 26 cases, with sepsis (96%) and exposure to nephrotoxic drugs (88%), especially aminoglycosides, being the commonest precipitating factors. Toxic levels of the latter were commonly documented. Patient survival was 45%. Requirement for mechanical ventilation resulted in a universally fatal outcome; age greater than 55 yr and the presence of CNS symptoms or signs were also significantly associated with a poor outcome. Non-ATN causes (urate nephropathy or obstruction) carried a better prognosis. However, only 4 patients (14%) lived for more than 6 months following ARF. Thus, although a subgroup of patients more likely to benefit from treatment can be identified, the overall prognosis is poor and limited by that of the underlying disease. The potential benefit of avoiding nephrotoxic drugs, especially aminoglycosides, in these patients is highlighted by this study.

Outcome prediction of acute renal failure in medical intensive care

Data acquired prospectively from 134 patients with acute renal failure requiring dialysis in a medical intensive care unit (ICU) were analysed in order to derive indicators predicting ICU-survival. Mortality in the ICU was 56.7%. Linear discriminant analysis correctly predicted outcome in 79.9% at the start of dialysis, and 84.7% at 48 h after the first dialysis. The most important predictive variables were mechanical ventilation and low blood pressure. On the other hand, the total correct classification rates achieved by a standardised system for scoring ICU-patients (APACHE II) did not exceed 58.2%. It is concluded that outcome prediction by APACHE II and even by the discriminant functions is too inaccurate to become the basis for clinical decisions either concerning the initiation or the continuation of dialysis treatment in ARF.

Continuous high volume venous-venous haemofiltration in acute renal failure

Continuous, high volume, venous-venous haemofiltration was used as renal support in 28 critically ill patients with acute renal failure. Fifteen patients survived and were subsequently discharged from the ITU. Although haemofiltration was highly effective in reducing the blood urea and serum creatinine, only survivors demonstrated a significant increase in arterial pH (medians before and at two days 7.28 and 7.49 respectively, p less than 0.005) with a reduction in severity of their illness (median APACHE II scores before and at two days 23 and 16, p less than 0.005). Patients who died remained severely ill and acidotic (median APACHE II scores before and at two days 26 and 28; median arterial pH values 7.32 and 7.31 respectively) and by day two of treatment, marked differences between the patient groups in APACHE II scores, mean arterial pressure, arterial pH and urine flow rate had developed. Haemofiltration with the correction of acute uraemia alone does not necessarily lead to a reduction in the severity of illness which in the critically ill more frequently reflects other organ dysfunction.

Acute renal failure in the elderly treated by one-time peritoneal dialysis

To determine the factors affecting outcome of acute renal failure (ARF) in the elderly, we retrospectively studied 44 patients over the age of 65 who had undergone acute peritoneal dialysis. Thirteen patients (29%) survived 2 months or longer after dialysis treatment ("survivors"). Thirty-one patients (71%) died within this period ("nonsurvivors"). The main factor distinguishing survivors was the frequency of sepsis (none of 13 survivors vs 17 of 31 nonsurvivors). Preexisting malignancy and total number of acute insults to renal function were significantly less frequent, and immediate clinical and biochemical outcome of dialysis significantly better in survivors. The overall complication rate of dialysis was high (31 of 44 patients), but was significantly lower in survivors. Acute peritoneal dialysis is a useful procedure in the management of ARF in the elderly. However, we suggest that elderly patients in whom sepsis is a contributory factor to the development of ARF do not benefit from peritoneal dialysis therapy.

Renal and liver function tests in surgical septicemia

The prognostic value of conventional renal and liver function tests was evaluated during surgical septicemia. Changes in renal function variables were associated with the development of septic shock. Creatinine clearance was the most sensitive variable in predicting the outcome of septic shock, but serum creatinine and urine output were also of some value in this respect. Significantly lower creatinine clearance and urine output values, as well as significantly higher serum creatinine concentrations, were thus observed during septic shock with fatal outcome compared to non-fatal septic shock. In septicemia not complicated with shock, the variables of renal function remained in the normal range irrespective of final outcome. Among the liver function tests, serum albumin and total protein concentration revealed significant differences in behaviour between survivors and patients dying with persistent septicemia. However, due to the small differences and considerable overlap observed between the two groups of patients during the first 2 weeks of septicemia, these two variables are of limited practical value as prognostic predictors. The other liver function tests gave no information as regards the outcome of septicemia in the present study.

The assessment of risk factors in 462 patients with acute renal failure

Risk factors associated with the mortality of patients with acute renal failure (ARF) were investigated. This was accomplished by a review of 462 patients with ARF and the utilization of a logistic regression analysis to develop a model that can be used to predict the mortality odds for an ARF patient. The significant risk factors were age, oliguria, pulmonary and cardiovascular complications, jaundice, and hypercatabolism. Based on these factors, our model was able to account for 77% of the mortality associated with ARF.

Acute renal failure: the tip of the iceberg?

This study reports the experience, during a six-year period, of the Aberdeen Renal Unit in the treatment of patients with acute renal failure. The combination of a relatively stable population base and a single regional dialysis centre has allowed the incidence of acute renal failure to be assessed. Approximately 30 patients per million population were dialysed annually for acute renal failure; 69 per cent of these patients (20.5 per million population per year) were dialysed for acute reversible intrinsic renal failure (ARIRF) and mortality in this group was 44 per cent. Patients with more severe disease at the time of presentation to the renal unit, as defined by a clinical severity score, had significantly reduced survival rates. However, it was not possible to predict the outcome in individual cases; ten of 24 patients with clinical severity scores which indicated a poor prognosis survived the period of oliguria and were discharged from hospital. The fact that other renal units dialyse fewer patients per million population per year for ARIRF probably reflects a reluctance to refer patients whose general condition appears poor. As the overall mortality rate reported in this study does not differ significantly from rates reported previously from centres treating a smaller proportion of patients, such decisions may not be correct. It is well known that facilities in Britain for treating patients with end-stage renal disease are inadequate; it now appears likely that some patients who might benefit from acute dialysis are being denied treatment for a potentially reversible disease process.

Probability of surviving postoperative acute renal failure. Development of a prognostic index

Sixty-five patients who developed postoperative acute renal failure requiring hemodialysis were retrospectively analyzed to identify variables that could be used to predict outcome. Our aim was to identify patients who would have an unfavorable outcome despite hemodialysis and to identify those factors that might be altered to improve outcome. A linear discriminant function capable of segregating survivors from nonsurvivors in the retrospective analysis was subsequently validated in a prospective fashion using a second patient population. Variables used were age, sex, number of transfusions, interval from onset of acute renal failure to dialysis, type of surgery, preoperative hypotension, and the presence of cardiac failure. Scores were formulated for each patient and then segregated into three groups: patients with no precedence for survival, patients with an intermediate risk of dying, and patients with low risk of dying. Based on the univariant analysis, the interval from onset of acute renal failure to first dialysis and the maximum serum creatinine prior to first dialysis were the only factors that might be altered to change mortality. The prognostic index we have developed enables one to select patients without a chance of survival.