Acute renal failure surprisingly common

WASHINGTON, Aug 18, 2005 (United Press International via COMTEX) -- The first multinational study of acute renal failure has found the condition occurs more frequently in intensive-care units than previously thought and is caused most often by septic shock.

Acute renal failure occurs when the kidneys are unable to perform their function of excreting wastes from the body. As defined in the study, published in this week's Journal of the American Medical Association, the condition is characterized by urine output of less than 200 milliliters in 12 hours or a blood urea nitrogen level higher than 84 milligrams per deciliter. At present, the only treatment for acute renal failure is dialysis, which facilitates removal of wastes while the kidneys heal themselves.

The study found 5.7 percent of ICU patients -- more than 1 in 20 -- suffer from acute renal failure at some point during their stay.

"Most people who work in an ICU would understand that ... but putting a number to it was difficult," said John Kellum, the study's lead author and a professor of critical-care medicine at the University of Pittsburgh School of Medicine.

Kellum told United Press International the study is the first step toward achieving a better understanding of acute renal failure and its treatment.

"I am not surprised that that percentage is that high at all," Teresa Wavra, a clinical practice specialist for the American Association of Critical Care Nurses, told United Press International. "A lot of my patients had some form of renal failure."

Wavra noted, however, that because more than 30 different definitions for acute renal failure have been used in the medical literature, specific percentages are difficult to pinpoint.

"Your percentage may be up or down based on what criteria you're using," Wavra said, adding that some studies focus their definition of acute renal failure on blood levels of creatinine, a byproduct of the muscle component creatine, which usually is excreted in the urine.

The study included 54 locations in 23 countries, from Australia to Uruguay. Around the world, the prevalence of acute renal failure is stable at about 6 percent, despite local treatment variations. Hemodialysis, which circulates the patient's blood through filters outside of the body, is the preferred method of treatment in industrial societies, while peritoneal dialysis, which temporarily infuses toxin-removing solutions into the abdomen, is more common in developing countries, Kellum explained.

More than 60 percent of acute-renal-failure patients in the study died in the hospital, but among patients who survived only 13.8 percent needed dialysis after leaving the hospital.

The researchers found the most common contributing factor to acute renal failure -- implicated in 47.5 percent of cases -- was sepsis, a systemic response to infection. For example, a lung infection could spread throughout the body and lead to kidney, respiratory and circulatory failure.

Wavra said sometimes it is not possible to identify the primary organism that sparked a septic reaction.

Other contributing factors include major surgery, heart failure and drug reactions.

Kellum said the traditional explanation for acute renal failure is inadequate blood flow to the kidneys, but now doctors are leaning toward the idea that systemic inflammations such as sepsis, interacting with other factors, cause the condition, although it is not yet known exactly how.

Wavra described sepsis as "the bane of a lot of critical-care nurses." Because the disease is difficult to halt once the process of organ destruction begins, the AACCN in 2004 became a sponsor of the American Sepsis Alliance Campaign, which promotes the prevention and early detection of the disease.

"They haven't figured it all out, or we'd be doing a better job," Wavra said.

She said acute renal failure frequently appears during the process of septic shock, and it currently is debated whether renal failure in sepsis is caused by hypotension or by cellular death. Cellular death is a hallmark feature of sepsis, as the immune system's function of getting rid of dead cells spirals out of control.

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Eva Sylwester is an intern for UPI Science News. E-mail: sciencemail@upi.com