Persistent arterial hyperammonemia can increase risk for liver failure complications
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Patients with acute liver failure and persistent arterial hyperammonemia were more likely to experience complications and had higher mortality risk than patients with lower ammonia levels in a recent study.
In a prospective observational study, researchers evaluated arterial ammonia levels of 295 patients with acute liver failure (ALF) daily for 5 days. Patients were divided into subgroups according to their levels at baseline, and further divided according to whether those levels persisted or decreased after 3 days.
Among the initial cohort, 138 patients died, with a median survival of 5 days after hospital admission. The median baseline ammonia level was higher among patients who died than those who survived (159 mcmol/L vs. 102 mcmol/L, P<.001).
Survival rates were lower among patients with persistent hyperammonemia (≥122 mcmol/L for 3 days, n=92) than among those whose high ammonia levels decreased after 3 days (n=65) (23% survival compared with 72%, P<.001). Patients with persistent hyperammonemia were more prone to cerebral edema (71% of patients compared with 37% among those whose levels decreased, P<.001), infections (67% vs. 28%, P=.003) and seizures (41% of patients vs. 7.7%, P<.001). An OR for mortality of 10.7 (95% CI, 3.5-32.8) was calculated for persistent hyperammonemia, compared with 2.4 (95% CI, 1.3-4.4) for high ammonia levels at baseline.
Patients with persistent mild hyperammonemia (between 85 mcmol/L and 122 mcmol/L for 3 days, n=58) were more likely to experience complications or die compared with patients whose ammonia levels decreased below 85 mcmol/L (n=80). Survival rates were lower (45% vs. 79%, P=.001), infections were more common (70% vs. 45% of patients, P=.003) and risk for death was higher (OR=2.8; 95% CI, 1.1-7.1) for those with persistent hyperammonemia compared with patients whose levels decreased.
“The results of our study suggest the early changes in ammonia levels predict complications and outcome better than static baseline levels,” the researchers wrote. “The existing prognostic models of ALF are based on admission parameters that have poor accuracy in predicting outcome. By using serial ammonia estimation, the risk stratification in ALF patients can be made dynamic, which can be more useful in therapeutic decision.”