Acute Renal Failure In Intensive Care Unit Research Articles

A positive fluid balance is associated with a worse outcome in patients with acute renal failure.

IntroductionDespite significant improvements in intensive care medicine, the prognosis of acute renal failure (ARF) remains poor, with mortality ranging from 40% to 65%. The aim of the present observational study was to analyze the influence of patient characteristics and fluid balance on the outcome of ARF in intensive care unit (ICU) patients.MethodsThe data were extracted from the Sepsis Occurrence in Acutely Ill Patients (SOAP) study, a multicenter observational cohort study to which 198 ICUs from 24 European countries contributed. All adult patients admitted to a participating ICU between 1 and 15 May 2002, except those admitted for uncomplicated postoperative surveillance, were eligible for the study. For the purposes of this substudy, patients were divided into two groups according to whether they had ARF. The groups were compared with respect to patient characteristics, fluid balance, and outcome.ResultsOf the 3,147 patients included in the SOAP study, 1,120 (36%) had ARF at some point during their ICU stay. Sixty-day mortality rates were 36% in patients with ARF and 16% in patients without ARF (P < 0.01). Oliguric patients and patients treated with renal replacement therapy (RRT) had higher 60-day mortality rates than patients without oliguria or the need for RRT (41% versus 33% and 52% versus 32%, respectively; P < 0.01). Independent risk factors for 60-day mortality in the patients with ARF were age, Simplified Acute Physiology Score II (SAPS II), heart failure, liver cirrhosis, medical admission, mean fluid balance, and need for mechanical ventilation. Among patients treated with RRT, length of stay and mortality were lower when RRT was started early in the course of the ICU stay.ConclusionIn this large European multicenter study, a positive fluid balance was an important factor associated with increased 60-day mortality. Outcome among patients treated with RRT was better when RRT was started early in the course of the ICU stay.

Machine-generated bicarbonate dialysate for continuous therapy: a prospective, observational cohort study

In 1995, we described the technique of adapting a haemodialysis (HD) machine to produce a composition-adjustable, bicarbonate-based fluid (as our primary source for dialysate) for continuous HD in intensive care unit (ICU) patients with acute renal failure (ARF). The following studies the clinical effects, biochemical changes and economic costs of this practice in a large cohort of patients at a single centre over the last 10 years. The CCF-ARF Support Registry (1995-2001) was used to identify 405 patients initially supported with bicarbonate continuous HD. The registry is a prospective, observational cohort database that captures demographic, dialysis therapy, laboratory and outcome data. All supported ARF patients were recorded from 1995-98, and then one in five patients from 1999 to 2001. We also reviewed records of the individual dialysis procedures, dialysate disposal, dialysate monitoring tests and specific costs. Continuous HD was performed for 1292 +/- 587 days from 1994 to 2004. Demographics [age 59.57 +/- 14.41 years, weight 84.2 +/- 24 kg, male 65%, chronic kidney disease (CKD) 34%] and ICU mortality (60.5%) were comparable to other reported series. Day 4 solute [BUN 52.3 mg/dl (95% CI 49.6-54.9), creatinine 2.79 mg/dl (95% CI 2.64-2.95)], electrolyte and acid-base balance [bicarbonate 24.12 mmol/l (95% CI 23.7-24.6)] were well controlled. Dialysate monitoring revealed no positive cultures or elevated endotoxin levels. Variable-composition dialysate was achieved and delivered to all patients without adverse consequences. The cost of dialysate actually declined over time (1995 = $0.91/l, 2005 = $0.67/l). We have demonstrated that ICU ARF patients can be safely, effectively and economically supported with continuous HD using this source.

Spectrum of acute renal failure in the intensive care unit: The PICARD experience

Acute renal failure (ARF) in the critically ill is associated with extremely high mortality rates. Understanding the changing spectrum of ARF will be necessary to facilitate quality improvement efforts and to design successful interventional trials. We conducted an observational cohort study of 618 patients with ARF in intensive care units at five academic medical centers in the United States. Participants were required to sign (or have a proxy sign) informed consent for data collection. A comprehensive data collection instrument captured more than 800 variables, most on a daily basis, throughout the course of ARF. Patient characteristics, dialysis status, and major outcomes were determined and stratified by clinical site. The mean age was 59.5 years, 41% were women, and 20% were of minority race or ethnicity. There was extensive comorbidity; 30% had chronic kidney disease, 37% had coronary artery disease, 29% had diabetes mellitus, and 21% had chronic liver disease. Acute renal failure was accompanied by extrarenal organ system failure in most patients, even those who did not require dialysis. Three hundred and ninety-eight (64%) patients required dialysis. The in-hospital mortality rate was 37%, and the rate of mortality or nonrecovery of renal function was 50%. The median hospital length of stay was 25 days (26 days, excluding patients who died). There is a changing spectrum of ARF in the critically ill, characterized by a large burden of comorbid disease and extensive extrarenal complications, obligating the need for dialysis in the majority of patients. There is wide variation across institutions in patient characteristics and practice patterns. These differences highlight the need for additional multicenter observational and interventional studies in ARF.

Reasons for non-enrollment in a cohort study of ARF: the Program to Improve Care in Acute Renal Disease (PICARD) experience and implications for a clinical trials network

Background: Acute renal failure (ARF) is associated strongly with in-hospital mortality and morbidity. Previous clinical trials of ARF have been hampered by the heterogeneous population affected, difficulty defining ARF, delays in identification of ARF, and significant comorbid conditions, among other factors. Methods: The Program to Improve Care in Acute Renal Disease (PICARD) phase I was a multicenter cohort study aimed to identify clinical characteristics and practice patterns associated with adverse and favorable outcomes in patients with ARF in intensive care units. Although PICARD used no interventions, signed informed consent was required of all study subjects or their proxies. Results: Signed informed consent was obtained in 645 of 1,243 ARF episodes (52%). The fraction of patients not enrolled and reasons for non-enrollment varied widely across the 5 PICARD centers. Refusal by potential study subjects was infrequent, although the absence of family or proxy (15%) and refusal by family or proxy (18%) accounted for large fractions of non-enrolled subjects. Death (23%) and discharge (11%) before study personnel could evaluate patients were additional important reasons for non-enrollment. Conclusion: Understanding reasons for non-enrollment may help rationalize mortality and other outcome differences seen in clinical trials and cohort studies that require informed consent compared with historic reports of “all comers” with ARF.

Evaluation of severity scoring systems in ICUs—translation, conversion and definition ambiguities as a source of inter-observer variability in Apache II, SAPS and OSF

To explore translation, conversion and definition ambiguities, when using severity scoring systems in patients admitted to intensive care units (ICUs). A prospective study of the prognosis of acute renal failure in ICUs. The study was conducted in 20 French ICUs. 360 patients presenting with severe acute renal failure were studied during their ICU stay. The inter-observer variability of Apache II (acute physiology and chronic health evaluation), SAPS (simplified acute physiology score), and OSF (organ-system failure) was considered. For Apache II, we explored the uncertainty of measurements arising from conversion into SI units, the rounding procedures used for the non-inclusive intervals defined for quantitative parameters such as age, mean arterial pressure (MAP) or serum creatinine, the absence of definition of acute renal failure (ARF) and its consequence on doubling serum creatinine values, and the absence of guidelines in the case of spontaneous ventilation when arterial blood gases (ABG) and forced inspiratory oxygen (FIO2) were not measured. The resulting variability was evaluated, calculating the lowest and the highest value of the scoring system for each patient. The mean difference by patient was greater than 1.5 (p < 0.0001). Other examples were presented and discussed for SAPS and OSF. Translation, conversion and definition ambiguities are a source of inter-observer variability and increase the risk of classification and/or selection biases. This gives rise to particular concern in the design and analysis of multicenter trials of meta-analysis, and improvement of these scoring systems should be envisaged in the future.

Is There a Reliable Index of Glomerular Filtration Rate in Critically Ill Patients?

Assessment of renal function in critically ill patients is important for appropriate individualization of dosage regimens and nutrition, but is complicated by a high incidence of acute renal failure (ARF). The most common cause of ARF in intensive care unit (ICU) patients is hypoperfusion. Other causes of ARF include intrinsic injury, nephrotoxicity, and postrenal obstruction. ARF is associated with a decreased glomerular filtration rate (GFR), reduced or maintained urine output (nonoliguric renal failure), and alterations in other commonly obtained urinary indices. Twenty-four-hour or shorter urinary creatinine clearance studies may overpredict GFR as creatinine is both filtered and secreted. The use of serum creatinine in empiric predictive equations is impaired in ICU patients because of decreases in creatinine production due to immobilization and malnutrition or increases in creatinine production due to catabolic illnesses. Adjustment of empiric methods by employing lean body weight, ideal body weight, or corrected serum creatinine values has not been evaluated against uncorrected values in this population, but is routinely performed in clinical practice. Inulin and radiolabeled substances are not practical for routine clinical use and may overpredict GFR in ARF due to backleak of large molecular-weight substances through the tubules. Comparative clinical trials have shown essentially equivalent performance of empiric methods relative to 24-hour urinary creatinine clearance in adults. No studies have compared these methods to a reference method for determination of GFR. Until conclusive data become available, clinicians should cautiously compare results from at least two independent methods of assessment to estimate renal functional impairment in ICU patients.