Associations Between Mean Arterial Pressure and Poor ICU Outcomes in Critically Ill Patients With Cirrhosis: Is 65 The Sweet Spot?

OBJECTIVES: Mean arterial pressure is critically important in patients with cirrhosis in the ICU, however, there is limited data to guide therapies and targets. DESIGN: Retrospective observational study. SETTING: Tertiary care ICU. PATIENTS: Two hundred and seventy-three critically ill patients with cirrhosis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We performed a comprehensive time-weighted mean arterial pressure analysis (time-weighted-average-mean arterial pressure and cumulative-time-below various mean arterial pressure-thresholds) during the first 24-hours after ICU admission (median: 25 mean arterial pressure measurements per-patient). Time-weighted-average-mean arterial pressure captures both the severity and duration of hypotension below a mean arterial pressure threshold and cumulative-time-below is the total time spent below a mean arterial pressure threshold. Individual univariable and multivariable logistic regression models were assessed for each time-weighted-average-mean arterial pressure and cumulative-time-below mean arterial pressure threshold (55, 60, 65, 70, and 75 mm Hg) for ICU-mortality. Time-weighted-average-mean arterial pressure: for 1 mm Hg decrease in mean arterial pressure below 75, 70, 65, 60, and 55 mm Hg, the odds for ICU-mortality were 14%, 18%, 26%, 41%, and 74%, respectively (p < 0.01, all thresholds). The association between time-weighted-average-mean arterial pressure and ICU-mortality for each threshold remained significant after adjusting for model for end-stage liver disease-sodium score, mechanical ventilation, vasopressor use, renal replacement therapy, grade 3/4 hepatic encephalopathy, WBC count, and albumin. Cumulative-time-below: odds for ICU-mortality were 4%, 6%, 10%, 12%, and 12% for each-hour spent below 75, 70, 65, 60, and 55 mm Hg, respectively. In the adjusted models, significant associations only remained for mean arterial pressure less than 65 mm Hg (odds ratio, 1.07; 95% CI, 1.00-1.14; p = 0.05) and < 60 mm Hg (odds ratio, 1.10; 95% CI, 1.01-1.18; p = 0.04). CONCLUSIONS: These data suggest that maintaining a mean arterial pressure of greater than 65 mm Hg may be a reasonable target in patients with cirrhosis admitted to the ICU. However, further prospective randomized trials are needed to determine the optimal mean arterial pressure-targets in this patient population.

Severe Alcohol-Associated Hepatitis Is Associated With Worse Survival in Critically Ill Patients With Acute on Chronic Liver Failure.

Differences in mortality between critically ill patients with severe alcohol-associated hepatitis (sAH) and acute-on-chronic liver failure (ACLF) and non-sAH ACLF (i.e., ACLF not precipitated by sAH) are unknown. Such differences are important, as they may inform on prognosis and optimal timing of liver transplantation (LT). Thus, we aimed to compare short-term and longer-term mortality between patients with sAH ACLF and patients with non-sAH ACLF who were admitted to the intensive care unit. Patients with ACLF admitted from 2016-2018 at two tertiary care intensive care units were analyzed. SAH was defined by the National Institute on Alcohol Abuse and Alcoholism's Alcoholic Hepatitis Consortium and Model for End-Stage Liver Disease score >20. Mortality without LT was compared between sAH ACLF and non-sAH ACLF using Fine and Gray's competing-risks regression. A total of 463 patients with ACLF (18% sAH and 82% non-sAH) were included. Compared to patients with non-sAH ACLF, patients with sAH ACLF were younger (49 vs. 56 years; P < 0.001) and had higher admission Model for End-Stage Liver Disease (MELD) (35 vs. 25; P < 0.001) and Chronic Liver Failure Consortium (CLIF-C) scores (61 vs. 57; P = 0.002). There were no significant differences between the two groups for vasopressor, mechanical ventilation, and hemodialysis use. The cumulative incidence of death was significantly higher in patients with sAH ACLF compared to patients with non-sAH ACLF: 30-day 74.7% versus 45.3%; 90-day 81.9% versus 57.4%; 180-day 83.2% versus 63.0% (unadjusted subdistribution hazard ratio [sHR] 1.88 [95% confidence interval (CI) 1.44-2.46]; P < 0.001). After adjusting for CLIF-C score and infection in a multivariable competing-risk model, patients with sAH ACLF had significantly higher risk of death (sHR 1.57 [95% CI 1.20-2.06]; P = 0.001) compared to patients with non-sAH ACLF. Conclusion: Critically ill patients with sAH ACLF have worse mortality compared to patients with non-sAH ACLF. These data may inform prognosis in patients with sAH and ACLF, and early LT referral in potentially eligible patients.

Amino-terminal TACE prodomain attenuates TNFR2 cleavage independently of the cysteine switch.

TNF-alpha-converting enzyme (TACE, ADAM17) cleaves membrane-associated cytokines and receptors and thereby regulates inflammatory and immune events, as well as lung development and mucin production. For example, the TACE-mediated cleavage of the type II 75-kDa TNF receptor (TNFR2) generates a soluble TNF-binding protein that modulates TNF bioactivity. TACE is synthesized as a latent proenzyme that is retained in an inactive state via an interaction between its prodomain and catalytic domain. Although the formation of an intramolecular bond between a cysteine in the prodomain and a zinc atom in the catalytic site had been thought to mediate this inhibitory activity, it was recently reported that the cysteine-switch motif is not required. Here, we hypothesized that the amino terminus of the TACE prodomain might contribute to the ability of the prodomain to maintain TACE in an inactive state independently of a cysteine-switch mechanism. We synthesized a 37-amino acid peptide corresponding to TACE amino acids 18-54 (N-TACE(18-54)) and assessed whether it possessed TACE inhibitory activity. In an in vitro model assay system, N-TACE(18-54) attenuated TACE-catalyzed cleavage of a TNFR2:Fc substrate. Furthermore, N-TACE(18-54) inhibited constitutive TNFR2 shedding from a human monocytic cell line by 42%. A 19-amino acid, leucine-rich domain, corresponding to TACE amino acids 30-48, demonstrated partial inhibitory activity. In summary, we have identified a subdomain within the amino terminus of the TACE prodomain that attenuates TACE catalytic activity independently of a cysteine-switch mechanism, which provides new insight into the regulation of TACE enzymatic activity.