Acute renal failure in hospitalized patients: part II

Association between acute kidney injury and serum procalcitonin levels and their diagnostic usefulness in critically ill patients

Procalcitonin (PCT) is a useful marker for the diagnosis of systemic inflammatory response syndrome. In addition, PCT is affected by renal function. However, few studies have investigated the relationship between PCT and the development of acute kidney injury (AKI). Hence, we investigated whether serum PCT levels at the time of admission were associated with the development of AKI and clinical outcomes. A total of 790 patients in whom PCT was measured on admission to the intensive care unit (ICU) were analyzed retrospectively. We attempted to investigate whether serum PCT levels measured at the time of admission could be used as a risk factor for the development of AKI in septic and nonseptic patients or as a risk factor for all-cause mortality, and diagnostic usefulness of PCT was further assessed. Serum PCT levels were significantly higher in patients with AKI than in those without AKI (P < 0.001). After multivariable adjustment for clinical factors, laboratory findings, and comorbidities, PCT as a continuous variable showed a significant association with AKI (OR 1.006, 95% CI [1.000–1.011]; P = 0.035). However, PCT was not effective in predicting mortality. The cut-off value of PCT for the prediction of AKI incidence was calculated to be 0.315 ng/ml, with sensitivity and specificity of 60.9% and 56.9%, respectively. The odds ratios (ORs) from an equation adjusted for optimum thresholds of PCT levels for developing AKI with and without sepsis were 2.422 (1.222–4.802, P = 0.011) and 1.798 (1.101–2.937, P = 0.019), respectively. However, there were no absolute differences between the pre- and posttest probabilities after including the PCT value for AKI development. This study suggests that the PCT value was higher in AKI patients than in non-AKI patients, but PCT measurement at the time of admission did not improve the prediction model for AKI.

Postoperative acute kidney injury in high-risk patients undergoing major abdominal surgery

PURPOSE

Acute kidney injury (AKI) is a frequent complication in high-risk patients undergoing major surgery and is associated with longer hospital stay, increased risk for nosocomial infection and significantly higher costs.

MATERIALS AND METHODS

A prospective observational study exploring the incidence of AKI (AKIN classification at any stage) in high-risk patients within 48 hours after major abdominal surgery was conducted. Patients' preoperative characteristics, intraoperative management, and outcome were evaluated for associations with AKI using a logistic regression model.

RESULTS

Data from 258 patients were analyzed. Thirty-one patients (12%) developed AKI, reaching the AKIN stage 1. No patient reached an AKIN stage higher than 1. AKI patients were older (75.2 vs 70.2 years; P = 0.0113) and had a higher body mass index (26.5 vs 25.1 kg/m(2)). In addition, AKI patients had a significantly longer ICU length of stay (3.4 vs 2.4 days; P= .0017). Creatinine levels of AKI patients increased significantly compared to the preoperative levels at 24 (P= .0486), 48 (P= .0011) and 72 hours (P= .0055), while after 72 hours it showed a downwards trend. At ICU discharge, 28 out of 31 patients (90.3%) recovered preoperative levels. Multivariate analysis identified age (OR 1.088; P= .002) and BMI (OR 1.124; P= .022) as risk factors for AKI development. Moreover, AKI development was an independent risk factor for ICU stays longer than 48 hours (OR 2.561; P= .019).

CONCLUSIONS

Mild AKI is a not rare complication in high-risk patients undergoing major abdominal surgery. Although in almost the totality of cases, the indicators of renal function recovered to preoperative levels, post-operative AKI represents a primary risk factor for a prolonged ICU stay.

Nephroscreen™: a diagnostic test for predicting acute renal failure?

Acute renal failure is a frequent and often fatal complication of hospitalized patients. While the risk of acute renal failure among select patient groups is well recognized, physicians currently rely on diagnostic tests such as changes of serum creatinine and indirect assessment of the glomerular filtration rate to diagnose acute renal failure. Although these parameters capture the degree of kidney function lost, they are not warning signs of evolving kidney injury. While the clinical emergence of acute renal failure is sudden, the pathologic changes preceding loss of kidney function are not so sudden. Nephroscreen is a fast and easy-to-use urine enzyme-linked immunosorbent assay test designed to quantify specific pathologic events preceding death of renal proximal tubule cells. It detects acute kidney damage days before serum creatinine rises and may open new avenues to defining acute renal failure as well as treating acute renal failure patients earlier and more effectively.

Reporting of estimated glomerular filtration rate: effect on physician recognition of chronic kidney disease and prescribing practices for elderly hospitalized patients

BACKGROUND

Physician recognition of chronic kidney disease (CKD) in elderly patients has been noted to be poor. These patients are at increased risk of medication dosing errors and acute renal failure.

OBJECTIVE

To investigate the effect of reporting estimated glomerular filtration rate (GFR) of elderly hospitalized patients on physician recognition of CKD and physician prescribing behaviors.

DESIGN

A retrospective combined with a prospective medical record review project.

SETTING

A large academic medical center.

PATIENTS

Patients included were 65 years of age or older and had creatinine values within the normal laboratory range (< 1.6 mg/dL).

INTERVENTION

Reporting a calculated estimate of GFR to physicians.

MEASUREMENTS

Rates of recognition of CKD were examined before and after the intervention. The effects of the intervention on prescription of renal-dosed antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDS) and cyclooxygenase- 2 inhibitors (COX-2) at hospital discharge were assessed.

RESULTS

A total of 260 and 198 patients were included before and after the intervention, respectively. Recognition of chronic kidney disease was low in both groups but demonstrated a significant increase following reporting of estimated GFR (3.9% to 12.6%, P < .001). Reporting of GFR was not associated with a significant decrease in prescription of NSAID/COX-2 medications or increased rates of correct dosing of antibiotics (P = .10 and P = .81, respectively).

CONCLUSIONS

Although reporting of estimated GFR was associated with improved physician recognition of CKD in elderly hospitalized patients, it did not lead to a change in physician prescribing. More extensive interventions are necessary to increase recognition and decrease medication dosing errors.

Risk factors for acute renal failure: inherent and modifiable risks

PURPOSE OF REVIEW

Our purpose is to discuss established risk factors in the development of acute renal failure and briefly overview clinical markers and preventive measures.

RECENT FINDINGS

Findings from the literature support the role of older age, diabetes, underlying renal insufficiency, and heart failure as predisposing factors for acute renal failure. Diabetics with baseline renal insufficiency represent the highest risk subgroup. An association between sepsis, hypovolemia, and acute renal failure is clear. Liver failure, rhabdomyolysis, and open-heart surgery (especially valve replacement) are clinical conditions potentially leading to acute renal failure. Increasing evidence shows that intraabdominal hypertension may contribute to the development of acute renal failure. Radiocontrast and antimicrobial agents are the most common causes of nephrotoxic acute renal failure. In terms of prevention, avoiding nephrotoxins when possible is certainly desirable; fluid therapy is an effective prevention measure in certain clinical circumstances. Supporting cardiac output, mean arterial pressure, and renal perfusion pressure are indicated to reduce the risk for acute renal failure. Nonionic, isoosmolar intravenous contrast should be used in high-risk patients. Although urine output and serum creatinine lack sensitivity and specificity in acute renal failure, they remain the most used parameters in clinical practice.

SUMMARY

There are identified risk factors of acute renal failure. Because acute renal failure is associated with a worsening outcome, particularly if occurring in critical illness and if severe enough to require renal replacement therapy, preventive measures should be part of appropriate management.

Effectiveness of nesiritide on dialysis or all-cause mortality in patients undergoing cardiothoracic surgery

BACKGROUND

Natriuretic peptides have been shown to have favorable renal effects. However, recent evidence suggests potential renal side effects in patients with congestive heart failure.

HYPOTHESIS

This study examined the effect of nesiritide (human B-type natriuretic peptide) on hemodialysis or death in patients undergoing cardiothoracic surgery.

METHODS

This retrospective cohort study included patients (n = 940) undergoing nontransplant adult cardiothoracic surgery between July 2001 and February 2004. Patients receiving nesiritide within 3 days after and not before surgery (n = 151) were compared with those not given nesiritide (n = 789) for incidence of hemodialysis or in-hospital death by Day 21 (HD/death). Patients with preexisting dialysis and intraoperative deaths were excluded. Forward inclusion multiple logistic regression was used based on published risk factors for HD/death.

RESULTS

Of 940 patients (318 coronary artery bypass graft, 348 valve, and 274 thoracic aorta), 36 required dialysis and 60 patients died (HD/death; n = 77). Adjusted for significant confounders (gender, age, procedure, intra-aortic balloon, baseline serum creatinine mg/dl [SCr], 1 day % SCr increase), nesiritide showed a statistically nonsignificant HD/death reduction (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.29-1.17; p = 0.129) in the group as a whole. When stratified by baseline SCr, a significant benefit was noted in patients with SCr > 1.0 (OR, 0.35; 95% CI 0.14-0.87; p = 0.024), while no significant effect was found in patients with SCr < 1.0 (OR, 1.55; 95% CI 0.48-5.07, p = 0.465).

CONCLUSIONS

Nesiritide appears promising in reducing the risk of dialysis or death in patients with SCr > 1.0 undergoing cardiothoracic surgery; however, no effect was noted with SCr < 1.0. This study provides strong rationale for a randomized trial.

N-acetylcysteine for radiocontrast-induced nephropathy: Potential role in the emergency department?

Objective:

To systematically review the efficacy and safety of N-acetylcysteine (NAC) for the prevention of radiocontrast-induced nephropathy (RIN), and to discuss its potential role in the emergency department.

Methodology:

We conducted a search of MEDLINE (from 1966 to December 2003), PubMed (1966 to December 2003) and EMBASE (1988 to December 2003) for English-language, prospective, randomized, controlled trials in humans using the search terms N-acetylcysteine, acetylcysteine, radiopharmaceuticals, contrast media, and kidney failure (acute).

Results:

Five trials support and 4 trials refute the hypothesis that NAC helps prevent RIN. In 7 of 9 trials, oral NAC was administered twice daily for 2 days, on the day before and on the day of the radiocontrast study — a regime not feasible for emergent situations. More recent trials suggest that adequate hydration and lower volumes of radiocontrast, rather than NAC, are more effective ways to prevent RIN.

Conclusion:

Although further study may be indicated, current evidence does not suggest that NAC has a role in the emergency prevention of RIN.

Molecular mechanisms of recovery from acute renal failure

OBJECTIVES

Despite technological advances in renal replacement therapy over the past few years, acute renal failure in the intensive care unit remains associated with high morbidity and mortality rates. In this article I review recent research aimed at elucidating mechanisms of renal recovery from acute injury.

DESIGN

Review of the literature.

CONCLUSIONS

A number of peptide growth hormones are reviewed, including epidermal growth factor, insulin-like growth factor-1, thyroxine, hepatocyte growth factor, and bone morphogenetic protein-7 promote renal regeneration in model systems. Unfortunately, despite promising studies in animal models of toxin and ischemia-induced acute tubular necrosis, human studies have not shown any clinical benefit. However, several of these molecules have not been studied in clinical trials. Existing pharmacologic strategies have a limited role in renal recovery. Finally, several recent studies have focused on the effects of renal replacement therapy on renal recovery, but additional studies are needed to confirm and extend these results.