FRIDAY, Feb. 9, 2007 (HealthDay News) -- A simple urine test can predict the survival of patients with a severe lung injury known as acute respiratory distress syndrome (ARDS), researchers report.
Higher levels of nitric oxide in urine were associated not only with improved survival but also with less time spent on ventilators and decreased rates of organ damage, concluded a report in the February issue of the American Journal of Respiratory and Critical Care Medicine.
"This is novel, because we are using urine as opposed to a blood test," added lead researcher Dr. Michael Matthay, a professor of medicine and anesthesia at the University of California, San Francisco.
An estimated 190,000 Americans each year suffer from ARDS because of complications from major infections, severe injuries or other conditions. Anywhere from 30 percent to 60 percent of them die from the lung injury.
The study included 566 patients enrolled in the U.S. National Heart, Lung, and Blood Institute's ARDS Network.
By the third day of the three-day study, 62 of the patients had died. All the survivors had significantly higher levels of nitric oxide than those who did not, the researchers found.
This relationship was not unexpected, since nitric oxide is involved in oxygen transport to tissues.
The study results, "mark a new approach to using urine testing to measure pathogenesis in lung injury," Matthay said. The urine test could eventually be used as a predictor in the treatment of ARDS patients, used in conjunction with other measurements, he said.
"We think it would be good to do additional studies in which we measured nitric oxide levels in blood and urine as well as in the airspaces of the lungs," Matthay said. "We want to assess in a new prospective study the value of this for identifying patients with a worse prognosis and a better prognosis."
An application for federal funding of such a study is being made, he said.
The nitric oxide urine test "can't function on its own, but it is a promising biomarker," Matthay said. "What we are currently testing, our group and others, is the additive value of this test to standard clinical assessments to determine the value of identifying patients' prognosis."
"The finding is pretty intriguing because of the close association with increased survival," noted Dr. Herbert P. Wiedemann, chairman of pulmonary, allergy and critical care medicine at the Cleveland Clinic. "This study is preliminary and hypothesis-generating. It provides an avenue for future investigation."
The test might not necessarily affect treatment of ARDS patients, he said, because the critical nature of the condition means that "normally we treat them all the same."
"But it could perhaps be a marker of prognosis, and that would be very helpful," Wiedemann said. "At this point, we don't have good markers of prognosis."
The test is also valuable because "it helps us understand the causes of mortality in ARDS, so it will help us investigate new therapies," he said.
More information
For more on ARDS, visit the U.S. National Library of Medicine.
