No abstract

BACKGROUND In critically ill, mechanically ventilated patients, daily interruption of sedation has been shown to reduce the time on ventilation and the length of stay in the intensive care unit (ICU). Data on whether a plan of no sedation, as compared with a plan of light sedation, has an effect on mortality are lacking. METHODS In a multicenter, randomized, controlled trial, we assigned, in a 1:1 ratio, mechanically ventilated ICU patients to a plan of no sedation (nonsedation group) or to a plan of light sedation (i.e., to a level at which the patient was arousable, defined as a score of −2 to −3 on the Richmond Agitation and Sedation Scale [RASS], on which scores range from −5 [unresponsive] to +4 [combative]) (sedation group) with daily interruption. The primary outcome was mortality at 90 days. Secondary outcomes were the number of major thromboembolic events, the number of days free from coma or delirium, acute kidney injury according to severity, the number of ICU-free days, and the number of ventilator-free days. Between-group differences were calculated as the value in the nonsedation group minus the value in the sedation group. RESULTS A total of 710 patients underwent randomization, and 700 were included in the modified intention-to-treat analysis. The characteristics of the patients at baseline were similar in the two trial groups, except for the score on the Acute Physiology and Chronic Health Evaluation (APACHE) II, which was 1 point higher in the nonsedation group than in the sedation group, indicating a greater chance of in-hospital death. The mean RASS score in the nonsedation group increased from −1.3 on day 1 to −0.8 on day 7 and, in the sedation group, from −2.3 on day 1 to −1.8 on day 7. Mortality at 90 days was 42.4% in the nonsedation group and 37.0% in the sedated group (difference, 5.4 percentage points; 95% confidence interval [CI], −2.2 to 12.2; P = 0.65). The number of ICU-free days and of ventilator-free days did not differ significantly between the trial groups. The patients in the nonsedation group had a median of 27 days free from coma or delirium, and those in the sedation group had a median of 26 days free from coma or delirium. A major thromboembolic event occurred in 1 patient (0.3%) in the nonsedation group and in 10 patients (2.8%) in the sedation group (difference, −2.5 percentage points; 95% CI, −4.8 to −0.7 [unadjusted for multiple comparisons]). CONCLUSIONS Among mechanically ventilated ICU patients, mortality at 90 days did not differ significantly between those assigned to a plan of no sedation and those assigned to a plan of light sedation with daily interruption. (Funded by the Danish Medical Research Council and others; NONSEDA ClinicalTrials.gov number, NCT01967680.

Treatment of hyperammonemia and hepatic encephalopathy in cirrhosis is an unmet clinical need. The aims of this study were to determine whether L-ornithine and phenylacetate/phenylbutyrate (administered as the pro-drug phenylbutyrate) (OP) combined are synergistic and produce sustained reduction in ammonia by L-ornithine acting as a substrate for glutamine synthesis, thereby detoxifying ammonia, and the phenylacetate excreting the ornithine-derived glutamine as phenylacetylglutamine in the urine. Sprague-Dawley rats were studied 4 weeks after bile duct ligation (BDL) or sham operation. Study 1: Three hours before termination, an internal carotid sampling catheter was inserted, and intraperitoneal saline (placebo), OP, phenylbutyrate, or L-ornithine were administered after randomization. BDL was associated with significantly higher arterial ammonia and brain water and lower brain myoinositol (P < 0.01, respectively), compared with sham-operated controls, which was significantly improved in the OP-treated animals; arterial ammonia (P < 0.001), brain water (P < 0.05), brain myoinositol (P < 0.001), and urinary phenylacetylglutamine (P < 0.01). Individually, L-ornithine or phenylbutyrate were similar to the BDL group. In study 2, BDL rats were randomized to saline or OP administered intraperitoneally for 6 hours or 3, 5, or 10 days and were sacrificed between 4.5 and 5 weeks. The results showed that the administration of OP was associated with sustained reduction in arterial ammonia (P < 0.01) and brain water (P < 0.01) and markedly increased arterial glutamine (P < 0.01) and urinary excretion of phenylacetylglutamine (P < 0.01) in each of the OP treated groups. Conclusion: The results of this study provide proof of the concept that L-ornithine and phenylbutyrate/phenylacetate act synergistically to produce sustained improvement in arterial ammonia, its brain metabolism, and brain water in cirrhotic rats. ( H epatic encephalopathy (HE) incorporates a spectrum of mental disturbances observed in patients with liver disease, ranging from minimal effects on quality of life to coma and death. 1 Hyperammonemia is considered central to the pathogenesis of HE, with arterial ammonia levels correlating with severity of intracranial hypertension and prediction of deaths from cerebral herniation in acute liver failure commensurate with an increase in brain delivery and uptake of ammonia. 2,3 In cirrhosis, induction of hyperammonemia has been shown to be associated with deterioration in neuropsychometric tests, worsening of brain osmolytes, and

Hyperammonemia is a feature of acute liver failure (ALF), which is associated with increased intracranial pressure (ICP) and brain herniation. We hypothesized that a combination of L-ornithine and phenylacetate (OP) would synergistically reduce toxic levels of ammonia by (1) L-ornithine increasing glutamine production (ammonia removal) through muscle glutamine synthetase and (2) I n patients with acute liver failure (ALF) increased intracranial pressure (ICP) leads to brain herniation, which accounts for 30% of deaths. 1 Liver failure results in hyperammonemia, which leads to toxic levels of ammonia in the brain. In patients with ALF, an arterial ammonia level of Ͼ150 mol/L has been shown to correlate with severity of intracranial hypertension 2 and deaths from brain herniation. 3 More recently, ammonia levels were shown to be predictive of increased ICP 4 and changes in blood ammonia concentration determined death due to cerebral edema in patients with ALF. 5Abbreviations: ALF, acute liver failure; GS, glutamine synthetase; HE, hepatic encephalopathy; ICP, intracranial pressure; OP, L-ornithine phenylacetate. From the