Arterial Ammonia Can Predict Outcome of Liver Failure
Levels at presentation can be used for risk stratification
TUESDAY, Dec. 27 (HealthDay News) -- In patients with acute liver failure, the level of arterial ammonia is predictive of outcome and useful as a means of risk stratification, according to a study in the January issue of Gut.
V. Bhatia, of the All India Institute of Medical Sciences in New Delhi, and colleagues analyzed data on 80 patients admitted with acute liver failure from March 2001 to December 2003. The patients' arterial ammonia levels were estimated on admission and all patients were followed up until death or complete recovery.
Of the sample, 42, or 52.5%, died. The median ammonia level for non-survivors was 174.7 μmol/l versus 105.0 μmol/l for survivors. An arterial ammonia level of 124 μmol/l or more predicted mortality with 78.6% sensitivity and 77.5% diagnostic accuracy. Complications such as deeper encephalopathy, cerebral edema, need for ventilation, and seizures were also more common in those patients with higher ammonia levels.
Using logistic regression analysis, the authors showed that pH, presence of cerebral edema and arterial ammonia were independent predictors of mortality. Using these variables, they devised a score predicting mortality risk at admission.
"Our findings encourage viewing acute liver failure as a 'hyperammonaemic' state, and provide a rational background for the use of ammonia-lowering therapies," the authors conclude.