Acute kidney insufficiency in the critically ill

Impact of the development of acute kidney injury on patients admitted to the pediatric intensive care unit

OBJECTIVE

To identify the risk factors for the development of acute kidney injury and for short and long-term mortality of patients with acute kidney injury after admission to the Pediatric Intensive Care Unit.

MATERIALS AND METHODS

Retrospective analysis of patients admitted to the Pediatric Intensive Care Unit from January 2004 to December 2008. Acute kidney injury was defined by the KDIGO criterion. Risk factors for acute kidney injury, in-hospital, and long-term mortality were obtained through multivariate logistic regression analysis. Long-term mortality (up to 2011) was obtained by searching the institution's database and by telephone contact with patients' family members.

RESULTS

A total of 434 patients were evaluated and the incidence of acute kidney injury was 64%. Most acute kidney injury episodes (78%) occurred within the first 24hours after admission to the Pediatric Intensive Care Unit. The risk factors for the development of acute kidney injury were: low volume of diuresis, younger age, mechanical ventilation, vasoactive drugs, diuretics, and amphotericin. Lower weight, positive fluid balance, acute kidney injury, dopamine use and mechanical ventilation were independent risk factors for in-hospital mortality. Long-term mortality was 17.8%. Systolic blood pressure, PRISM score, low volume of diuresis, and mechanical ventilation were independent risk factors associated with long-term mortality after admission to the Pediatric Intensive Care Unit.

CONCLUSION

Acute kidney injury was a frequent, early event, and was associated with in-hospital mortality and long-term mortality after admission to the Pediatric Intensive Care Unit.

The role of medications and their management in acute kidney injury

Prior to 2002, the incidence of acute renal failure (ARF) varied as there was no standard definition. To better understand its incidence and etiology and to develop treatment and prevention strategies, while moving research forward, the Acute Dialysis Quality Initiative workgroup developed the RIFLE (risk, injury, failure, loss, end-stage kidney disease) classification. After continued data suggesting that even small increases in serum creatinine lead to worse outcomes, the Acute Kidney Injury Network (AKIN) modified the RIFLE criteria and used the term acute kidney injury (AKI) instead of ARF. These classification and staging systems provide the clinician and researcher a starting point for refining the understanding and treatment of AKI. An important initial step in evaluating AKI is determining the likely location of injury, generally classified as prerenal, renal, or postrenal. There is no single biomarker or test that definitively defines the mechanism of the injury. Identifying the insult(s) requires a thorough assessment of the patient and their medical and medication histories. Prerenal injuries arise primarily due to renal hypoperfusion. This may be the result of systemic or focal conditions or secondary to the effects of drugs such as nonsteroidal anti-inflammatory drugs, calcineurin inhibitors (CIs), and modulators of the renin-angiotensin-aldosterone system. Renal, or intrinsic, injury is an overarching term that represents complex conditions leading to considerable damage to a component of the intrinsic renal system (renal tubules, glomerulus, vascular structures, inter-stitium, or renal tubule obstruction). Acute tubular necrosis and acute interstitial nephritis are the more common types of intrinsic renal injury. Each type of injury has several drugs that are implicated as a possible cause, with antiinfectives being the most common. Postrenal injuries that result from obstruction block the flow of urine, leading to hydronephrosis and subsequent damage to the renal parenchyma. Drugs associated with tubular obstruction include acyclovir, methotrexate, and several antiretrovirals. Renal recovery from drug-induced AKI begins once the offending agent has been removed, if clinically possible, and is complete in most cases. It is uncommon that renal replacement therapy will be needed while recovery occurs. Pharmacists can play a pivotal role in identifying possible causes of drug-induced AKI and limit their toxic effect by identifying those most likely to cause or contribute to injury. Dose adjustment is critical during changes in renal function, and the pharmacist can ensure that optimal therapy is provided during this critical time.