BRUSSELS—A simple measurement indicating global vascular function may help to assess prognoses in critically ill patients: An increasing microalbuminuria level during the first 48 hours after admission to an intensive care unit (ICU) predicts elevated risk for acute respiratory failure (ARF), multiple organ failure (MOF), and overall mortality.[1]

Monitoring microalbuminuria is “a neat way to get a handle on alterations in endothelial cell function. It’s a rather simple test which is able to tell us about the amount of vascular leakage,” said Jean-Louis Vincent, MD, PhD. “Whenever you have a large increase in inflammatory mediators, you have increases in capillary permeability,” explained Dr. Vincent, Professor and Head of Intensive Care at Erasme University Hospital. In critical illness, microvascular leakage “concerns all vessels: It can occur anywhere in the body,” he added. “But the kidneys are more easily monitored.” Because renal concentrating mechanisms amplify increases in extravasated protein caused by glomerular permeability changes, microalbuminuria may be a sensitive marker for global alterations in endothelial function.

To test the value of this measurement for predicting ARF and MOF, Dr. Vincent and colleagues monitored microalbuminuria levels in 40 adult medical patients upon ICU admission and eight, 24, 48, 72, 96, and 120 hours later. Patients were then grouped according to whether microalbuminuria increased or decreased, and trends were compared with APACHE II scores on the first day and with incidence of ARF and MOF and sequential organ failure assessment (SOFA) scores over the entire ICU stay.

Among the 14 patients whose microalbuminuria increased during the first 48 hours (from a mean of 5.2 to a mean of 19.0 mg/dL), the mortality rate was significantly higher (43% vs 15%) than among the 26 patients with decreasing microalbuminuria (from a mean of 16.4 to a mean of 7.8 mg/dL). These groups also significantly differed in severity-of-illness scores (mean APACHE II, 16 vs 10; mean total SOFA, 8 vs 5). Presence of increasing microalbuminuria within the first 48 hours after admission had a positive predictive value for ARF of 57% and a negative predictive value of 100%. Increasing microalbuminuria during the initial 48 hours also had a positive predictive value for MOF of 50% and a negative predictive value of 96%.

MEASUREMENTS WIDELY FEASIBLE, USEFUL

Because microalbuminuria measurement does not require special equipment, “it’s easily obtained in every ICU in the world … and so it may help identify patients at risk,” Dr. Vincent told PULMONARY REVIEWS. “We are planning to do a larger study and see how it could contribute to triage.” But, he cautioned, “It won’t work in all patients. If there is a severe kidney infection, then microalbuminuria measurements may not be relevant. Some patients may have preexisting microalbuminuria, especially patients with diabetes.” However, he emphasized, “It’s not only looking at absolute levels that’s important but following the trends … we need to look at changes over time.”

—Mimi Zucker, PhD

Reference
1. Abid O, Sun Q, Sugimoto K, et al. Predictive value of microalbuminuria in medical ICU patients. Chest. 2001;120:1984-1988.

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