Serial Shock Severity Assessment Within 72 Hours After Diagnosis: A Cardiogenic Shock Working Group Report.

BACKGROUND: The Cardiogenic Shock Working Group-modified Society for Cardiovascular Angiography and Interventions (CSWG-SCAI) staging was developed to risk stratify cardiogenic shock (CS) severity. Data showing progressive changes in SCAI stages and outcomes are limited. OBJECTIVES: We investigated serial changes in CSWG-SCAI stages and outcomes of patients presenting with cardiogenic shock complicating acute myocardial infarction (MI-CS) and heart failure-related CS (HF-CS). METHODS: The multicenter CSWG registry was queried. CSWG-SCAI stages were computed at CS diagnosis and 24, 48, and 72 hours. RESULTS: A total of 3,268 patients (57% HF-CS; 27% MI-CS) were included. At CS diagnosis, CSWG-SCAI stage breakdown was 593 (18.1%) stage B, 528 (16.2%) stage C, 1,659 (50.8%) stage D, and 488 (14.9%) noncardiac arrest stage E. At 24 hours, >50% of stages B and C patients worsened, but 86% of stage D patients stayed at stage D. Among stage E patients, 54% improved to stage D and 36% stayed at stage E by 24 hours. Minimal SCAI stage changes occurred beyond 24 hours. SCAI stage trajectories were similar between MI-CS and HF-CS groups. Within 24 hours, unadjusted mortality rates of patients with any SCAI stage worsening or improving were 44.6% and 34.2%, respectively. Patients who presented in or progressed to stage E by 24 hours had the worst prognosis. Survivors had lower lactate than nonsurvivors. CONCLUSIONS: Most patients with CS changed SCAI stages within 24 hours from CS diagnosis. Stage B patients were at high risk of worsening shock severity by 24 hours, associated with excess mortality. Early CS recognition and serial assessment may improve risk stratification.

"The Psychiatric Domain of Post-Intensive Care Syndrome: A Review for the Intensivist".

Post-intensive care syndrome (PICS) is a clinical syndrome characterized by new or worsening changes in mental health, cognition, or physical function that persist following critical illness. The psychiatric domain of PICS encompasses new or worsened psychiatric burdens following critical illness, including post-traumatic stress disorder (PTSD), depression, and anxiety. Many of the established predisposing and precipitating factors for the psychiatric domain of PICS are commonly found in the setting of critical illness, including mechanical ventilation (MV), exposure to sedating medications, and physical restraint. Importantly, previous psychiatric history is a strong risk factor for the development of the psychiatric domain of PICS and should be considered when screening patients to diagnose psychiatric impairment and interventions. Delirium has been associated with psychiatric symptoms following ICU admission, therefore prevention warrants careful consideration. Dexmedetomidine has been shown to have the lowest risk for development of delirium when compared to other sedatives and has been the only sedative studied in relation to the psychiatric domain of PICS. Nocturnal dexmedetomidine and intensive care unit (ICU) diaries have been associated with decreased psychiatric burden after ICU discharge. Studies evaluating the impact of other intra-ICU practices on the development of the psychiatric domain of PICS, including the ABCDEF bundle, depth of sedation, and daily spontaneous awakening trials, have been limited and inconclusive. The psychiatric domain of PICS is difficult to treat and may be less responsive to multidisciplinary post-discharge programs and targeted interventions than the cognitive and physical domains of PICS. Given the high morbidity associated with the psychiatric domain of PICS, intensivists should familiarize themselves with the risk factors and intra-ICU interventions that can mitigate this important and under-recognized condition.

Factors associated with acute limb ischemia in cardiogenic shock and downstream clinical outcomes: Insights from the Cardiogenic Shock Working Group.

BACKGROUND: There are limited data depicting the prevalence and ramifications of acute limb ischemia (ALI) among cardiogenic shock (CS) patients. METHODS: We employed data from the Cardiogenic Shock Working Group (CSWG), a consortium including 33 sites. We constructed a multi-variable logistic regression to examine the association between clinical factors and ALI, we generated another logistic regression model to ascertain the association of ALI with mortality. RESULTS: There were 7,070 patients with CS and 399 (5.6%) developed ALI. Patients with ALI were more likely to be female (40.4% vs 29.4%) and have peripheral arterial disease (13.8% vs 8.3%). Stratified by maximum society for cardiovascular angiography & intervention (SCAI) shock stage, the rates of ALI were stage B 0.0%, stage C 1.8%, stage D 4.1%, and stage E 10.3%. Factors associated with higher risk for ALI included: peripheral vascular disease OR 2.24 (95% CI: 1.53-3.23; p < 0.01) and ≥2 mechanical circulatory support (MCS) devices OR 1.66 (95% CI: 1.24-2.21, p < 0.01). ALI was highest for venous-arterial extracorporeal membrane oxygenation (VA-ECMO) patients (11.6%) or VA-ECMO+ intra-aortic balloon pump (IABP)/Impella CP (16.6%) yet use of distal perfusion catheters was less than 50%. Mortality was 38.0% for CS patients without ALI but 57.4% for CS patients with ALI. ALI was significantly associated with mortality, adjusted OR 1.40 (95% CI 1.01-1.95, p < 0.01). CONCLUSIONS: The rate of ALI was 6% among CS patients. Factors most associated with ALI include peripheral vascular disease and multiple MCS devices. The downstream ramifications of ALI were dire with a considerably higher risk of mortality.

Circulating Proteome Analysis Identifies Reduced Inflammation After Initiation of Hemodynamic Support with Either Veno-Arterial Extracorporeal Membrane Oxygenation or Impella in Patients with Cardiogenic Shock.

In-hospital mortality associated with cardiogenic shock (CS) remains high despite the use of percutaneous assist devices. We sought to determine whether support with VA-ECMO or Impella in patients with CS alters specific components of the plasma proteome. Plasma samples were collected before device implantation and 72 h after initiation of support in 11 CS patients receiving ECMO or Impella. SOMAscan was used to detect 1305 circulating proteins. Sixty-seven proteins were changed after ECMO (18 upregulated and 49 downregulated, p < 0.05), 38 after Impella (10 upregulated and 28 downregulated, p < 0.05), and only eight proteins were commonly affected. Despite minimal protein overlap, both devices were associated with markers of reduced inflammation and increased apoptosis of inflammatory cells. In summary, ECMO and Impella are associated with reduced expression of inflammatory markers and increased markers of inflammatory cell death. These circulating proteins may serve as novel targets of therapy or biomarkers to tailor AMCS use.

Outcomes With Single-Site Dual-Lumen Versus Multisite Cannulation for Adults With COVID-19 Respiratory Failure Receiving Venovenous Extracorporeal Membrane Oxygenation.

OBJECTIVES: To determine whether multisite versus single-site dual-lumen (SSDL) cannulation is associated with outcomes for COVID-19 patients requiring venovenous extracorporeal membrane oxygenation (VV-ECMO). DESIGN: Retrospective analysis of the Extracorporeal Life Support Organization Registry. Propensity score matching (2:1 multisite vs SSDL) was used to control for confounders. PATIENTS: The matched cohort included 2,628 patients (1,752 multisite, 876 SSDL) from 170 centers. The mean ( sd ) age in the entire cohort was 48 (11) years, and 3,909 (71%) were male. Patients were supported with mechanical ventilation for a median (interquartile range) of 79 (113) hours before VV-ECMO support. INTERVENTIONS: None. MEASUREMENTS: The primary outcome was 90-day survival. Secondary outcomes included survival to hospital discharge, duration of ECMO support, days free of ECMO support at 90 days, and complication rates. MAIN RESULTS: There was no difference in 90-day survival (49.4 vs 48.9%, p = 0.66), survival to hospital discharge (49.8 vs 48.2%, p = 0.44), duration of ECMO support (17.9 vs 17.1 d, p = 0.82), or hospital length of stay after cannulation (28 vs 27.4 d, p = 0.37) between multisite and SSDL groups. More SSDL patients were extubated within 24 hours (4% vs 1.9%, p = 0.001). Multisite patients had higher ECMO flows at 24 hours (4.5 vs 4.1 L/min, p < 0.001) and more ECMO-free days at 90 days (3.1 vs 2.0 d, p = 0.02). SSDL patients had higher rates of pneumothorax (13.9% vs 11%, p = 0.03). Cannula site bleeding (6.4% vs 4.7%, p = 0.03), oxygenator failure (16.7 vs 13.4%, p = 0.03), and circuit clots (5.5% vs 3.4%, p = 0.02) were more frequent in multisite patients. CONCLUSIONS: In this retrospective study of COVID-19 patients requiring VV-ECMO, 90-day survival did not differ between patients treated with a multisite versus SSDL cannulation strategy and there were only modest differences in major complication rates. These findings do not support the superiority of either cannulation strategy in this setting.

The Impact of a Pharmacist-Driven Multicomponent Sleep-Promoting Protocol on Delirium in Critically Ill Patients.

Background: Sleep deprivation is reported in 80% of patients in the intensive care unit (ICU) and is associated with delirium. Guidelines recommend implementing a sleep-promoting protocol in critically ill patients which may increase the quantity and quality of sleep and may decrease delirium. Our objective was to implement a pharmacist-led interdisciplinary sleep-promoting protocol and analyze its impact on delirium in ICU patients receiving mechanical ventilation (MV). Methods: The study involved pre-implementation education, protocol development, and post-implementation analysis. ICU pharmacists completed prospective patient chart reviews to reduce exposure to deliriogenic medications and assess the need for a pharmacologic sleep aid. The primary outcome was the incidence of delirium and delirium-free days. Secondary outcomes included ICU length of stay (LOS), incidence of MV, and pharmacist medication interventions. Results: Post-protocol patients (n = 185) had a higher incidence of delirium compared to pre-protocol patients (n = 237) (51.3% vs 39.0%; P = .01). Post-protocol patients had a higher average APACHE III score (P = <.001). Delirium-free days were not significantly different between groups (P = .97). Difference in ICU LOS was not significant (P = .80). More patients received MV post-protocol implementation (55.7% vs 36.1%; P < .001). Pharmacists documented a total of 113 medication interventions. Conclusion and Relevance: A pharmacist-led, ICU sleep-promoting protocol was successfully implemented but did not reduce the incidence of delirium or the administration of insomnia agents. Post-protocol patients had higher disease severity and were more likely to receive MV. Incidence of delirium was consistent with the national reported prevalence of ICU delirium. ICU pharmacists on all shifts had an active role in optimizing sleep.

Characterization of SARS-CoV-2 Aerosols Dispersed During Noninvasive Respiratory Support of Patients With COVID-19.

BACKGROUND: In the midst of the COVID-19 pandemic, noninvasive respiratory support (NRS) therapies such as high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) were central to respiratory care. The extent to which these treatments increase the generation and dispersion of infectious respiratory aerosols is not fully understood. The objective of this study was to characterize SARS-CoV-2 aerosol dispersion from subjects with COVID-19 undergoing NRS therapy. METHODS: Several different aerosol sampling devices were used to collect air samples in the vicinity of 31 subjects with COVID-19, most of whom were receiving NRS therapy, primarily HFNC. Aerosols were collected onto filters and analyzed for the presence of SARS-CoV-2 RNA. Additional measurements were collected in an aerosol chamber with healthy adult subjects using respiratory therapy devices under controlled and reproducible conditions. RESULTS: Fifty aerosol samples were collected from subjects receiving HFNC or NIV therapy, whereas 6 samples were collected from subjects not receiving NRS. Only 4 of the 56 aerosol samples were positive for SARS-CoV-2 RNA, and all positive samples were collected using a high air flow scavenger mask collection device placed in close proximity to the subject. The chamber measurements with healthy subjects did not show any significant increase in aerosol dispersion caused by the respiratory therapy devices compared to baseline. CONCLUSIONS: Our findings demonstrate very limited detection of SARS-CoV-2-containing aerosols in the vicinity of subjects with COVID-19 receiving NRS therapies in the clinical setting. These results, combined with controlled chamber measurements showing that HFNC and NIV device usage was not associated with increased aerosol dispersion, suggest that NRS therapies do not result in increased dispersal of aerosols in the clinical setting.

Treatment Intensity for the Management of Cardiogenic Shock: Comparison Between STEMI and Non-STEMI.

Background: Cardiogenic shock is a leading cause of mortality in patients with acute myocardial infarction. Objectives: The authors sought to compare clinical characteristics, hospital trajectory, and drug and device use between patients with ST-segment elevation myocardial infarction-related cardiogenic shock (STEMI-CS) and those without (non-ST-segment elevation myocardial infarction complicated by cardiogenic shock [NSTEMI-CS]). Methods: We analyzed data from 1,110 adult admissions with cardiogenic shock complicating acute myocardial infarction (AMI-CS) across 17 centers within Cardiogenic Shock Working Group. The primary end point was in-hospital mortality. Results: Our study included 1,110 patients with AMI-CS, of which 731 (65.8%) had STEMI-CS and 379 (34.2%) had NSTEMI-CS. Most patients were male (STEMI-CS: 71.6%, NSTEMI-CS: 66.5%) and White (STEMI-CS: 53.8%, NSTEMI-CS: 64.1%). In-hospital mortality was 41% and was similar among patients with STEMI-CS and NSTEMI-CS (43% vs 39%, P = 0.23). Patients with out-of-hospital cardiac arrest had higher in-hospital mortality in patients with NSTEMI-CS (63% vs 36%, P = 0.006) as compared to patients with STEMI-CS (52% vs 41%, P = 0.16). Similar results were observed for in-hospital cardiac arrest in patients with STEMI-CS (63% vs 33%, P < 0.001) and NSTEMI-CS (60% vs 32%, P < 0.001). Only 27% of patients with STEMI-CS and 12% of NSTEMI-CS received both a drug and temporary mechanical circulatory support device during the first 24 hours, which increased to 78% and 61%, respectively, throughout the course of the hospitalization (P < 0.001 for both). Conclusions: Despite increasing use of inotropic and vasoactive support and mechanical circulatory support throughout the hospitalization, both patients with STEMI-CS and NSTEMI-CS remain at increased risk for in-hospital mortality. Randomized controls trials are needed to elucidate whether timing and sequence of escalation of support improves outcomes in patients with AMI-CS.

Strategies to reduce limb ischemia in peripheral venoarterial extracorporeal membrane oxygenation: A systematic review and Meta-analysis.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) provides cardiovascular and respiratory support for patients in cardiogenic shock; yet, complications are a frequent source of morbidity and mortality. Limb ischemia can be potentially mitigated by limp perfusion protection strategies (LPPS). We performed a systematic review and meta-analysis to evaluate the safety and efficacy of two LPPS in patients treated with peripheral VA-ECMO - prophylactic insertion of a distal perfusion catheter (DPC) and small bore (<17 Fr) arterial return cannula. Among 22 included studies, limb ischemia was reduced in patients receiving a small arterial cannula (OR 0.40, 95% CI 0.24-0.65; p < 0.001) and in patients receiving a prophylactic DPC (OR 0.31, 95% CI 0.21-0.47; p < 0.001). Mortality was not significantly reduced with either a small arterial cannula (OR 0.70, 95% CI 0.23-2.18; p = 0.54) or prophylactic DPC strategy (OR 0.89, 95% CI 0.67-1.17; p = 0.40). As such, prophylactic insertion of a DPC or smaller bore arterial return cannula appear to reduce the risk of lower limb ischemia in this analysis. Further data are needed to confirm these findings. Registration: Registered in PROSPERO Database (Registration CRD42020215677).

Naloxegol to Prevent Constipation in ICU Adults Receiving Opioids: A Randomized Double-Blind Placebo-Controlled Pilot Trial.

Background: Constipation is frequent in critically ill adults receiving opioids. Naloxegol (N), a peripherally acting mu-receptor antagonist (PAMORA), may reduce constipation. The objective of this trial was to evaluate the efficacy and safety of N to prevent constipation in ICU adults receiving opioids. Methods and Patients. In this single-center, double-blind, randomized trial, adults admitted to a medical ICU receiving IV opioids (≥100 mcg fentanyl/day), and not having any of 17 exclusion criteria, were randomized to N (25 mg) or placebo (P) daily randomized to receive N (25mg) or placebo (P) and docusate 100 mg twice daily until ICU discharge, 10 days, or diarrhea (≥3 spontaneous bowel movement (SBM)/24 hours) or a serious adverse event related to study medication. A 4-step laxative protocol was initiated when there was no SBM ≥3 days. Results: Only 318 (20.6%) of the 1542 screened adults during the 1/17-10/19 enrolment period met all inclusion criteria. Of these, only 19/381 (4.9%) met all eligibility criteria. After 7 consent refusals, 12 patients were randomized. The study was stopped early due to enrolment futility. The N (n = 6) and P (n = 6) groups were similar. The time to first SBM (N 41.4 ± 31.7 vs. P 32.5 ± 25.4 hours, P = 0.56) was similar. The maximal daily abdominal pressure was significantly lower in the N group (N 10 ± 4 vs. P 13 ± 5, P = 0.002). The median (IQR) daily SOFA scores were higher in N (N 7 (4, 8) vs. P 4 (3, 5), P < 0.001). Laxative protocol use was similar (N 83.3% vs. P 66.6%; P = 0.51). Diarrhea prevalence was high but similar (N 66.6% vs. P 66.6%; P = 1.0). No patient experienced opioid withdrawal. Conclusions: Important recruitment challenges exist for ICU trials evaluating the use of PAMORAs for constipation prevention. Despite being underpowered, our results suggest time to first SBM with naloxegol, if different than P, may be small. The effect of naloxegol on abdominal pressure, SOFA, and the interaction between the two requires further research.

Kidney Recovery and Death in Critically Ill Patients With COVID-19-Associated Acute Kidney Injury Treated With Dialysis: The STOP-COVID Cohort Study.

RATIONALE & OBJECTIVE: Acute kidney injury treated with kidney replacement therapy (AKI-KRT) occurs frequently in critically ill patients with coronavirus disease 2019 (COVID-19). We examined the clinical factors that determine kidney recovery in this population. STUDY DESIGN: Multicenter cohort study. SETTING & PARTICIPANTS: 4,221 adults not receiving KRT who were admitted to intensive care units at 68 US hospitals with COVID-19 from March 1 to June 22, 2020 (the "ICU cohort"). Among these, 876 developed AKI-KRT after admission to the ICU (the "AKI-KRT subcohort"). EXPOSURE: The ICU cohort was analyzed using AKI severity as the exposure. For the AKI-KRT subcohort, exposures included demographics, comorbidities, initial mode of KRT, and markers of illness severity at the time of KRT initiation. OUTCOME: The outcome for the ICU cohort was estimated glomerular filtration rate (eGFR) at hospital discharge. A 3-level outcome (death, kidney nonrecovery, and kidney recovery at discharge) was analyzed for the AKI-KRT subcohort. ANALYTICAL APPROACH: The ICU cohort was characterized using descriptive analyses. The AKI-KRT subcohort was characterized with both descriptive analyses and multinomial logistic regression to assess factors associated with kidney nonrecovery while accounting for death. RESULTS: Among a total of 4,221 patients in the ICU cohort, 2,361 (56%) developed AKI, including 876 (21%) who received KRT. More severe AKI was associated with higher mortality. Among survivors, more severe AKI was associated with an increased rate of kidney nonrecovery and lower kidney function at discharge. Among the 876 patients with AKI-KRT, 588 (67%) died, 95 (11%) had kidney nonrecovery, and 193 (22%) had kidney recovery by the time of discharge. The odds of kidney nonrecovery was greater for lower baseline eGFR, with ORs of 2.09 (95% CI, 1.09-4.04), 4.27 (95% CI, 1.99-9.17), and 8.69 (95% CI, 3.07-24.55) for baseline eGFR 31-60, 16-30, ≤15 mL/min/1.73 m2, respectively, compared with eGFR > 60 mL/min/1.73 m2. Oliguria at the time of KRT initiation was also associated with nonrecovery (ORs of 2.10 [95% CI, 1.14-3.88] and 4.02 [95% CI, 1.72-9.39] for patients with 50-499 and <50 mL/d of urine, respectively, compared to ≥500 mL/d of urine). LIMITATIONS: Later recovery events may not have been captured due to lack of postdischarge follow-up. CONCLUSIONS: Lower baseline eGFR and reduced urine output at the time of KRT initiation are each strongly and independently associated with kidney nonrecovery among critically ill patients with COVID-19.

Lactate Clearance Is Associated With Improved Survival in Cardiogenic Shock: A Systematic Review and Meta-Analysis of Prognostic Factor Studies.

OBJECTIVE: Elevated blood lactate levels are strongly associated with mortality in patients with cardiogenic shock. Recent evidence suggests that the degree and rate at which blood lactate levels decrease after the initiation of treatment may be equally important in patient prognosis. We performed a systematic review and meta-analysis to evaluate the usefulness of lactate clearance as a prognostic factor in cardiogenic shock. METHODS AND RESULTS: We performed searches of Ovid MEDLINE, Elsevier EMBASE, EBM Reviews-Cochrane Central Register of Controlled Trials, and Web of Science to identify studies comparing lactate clearance between survivors and nonsurvivors at one or more timepoints. Both prospective and retrospective studies were eligible for inclusion. Two study investigators independently screened, extracted data, and assessed the quality of all included studies. Twelve studies were included in the meta-analysis. The median lactate clearance at 6-8 hours was 21.9% (interquartile range [IQR] 14.6%-42.1%) in survivors and 0.6% (IQR -3.7% to 14.6%) in nonsurvivors. At 24 hours, the median lactate clearance was 60.7% (IQR 58.1%-76.3%) and 40.3% (IQR 30.2%-55.8%) in survivors and nonsurvivors, respectively. Accordingly, the pooled mean difference in lactate clearance between survivors and nonsurvivors at 6-8 hours was 17.3% (95% CI 11.6%-23.1%, P < .001) at 6-8 hours and 27.9% (95% CI 14.1%-41.7%, P < .001) at 24 hours. CONCLUSIONS: Survivors had significantly greater lactate clearance at 6-8 hours and at 24 hours compared with nonsurvivors, suggesting that lactate clearance is an important prognostic marker in cardiogenic shock.

Association Between Early Treatment With Tocilizumab and Mortality Among Critically Ill Patients With COVID-19.

Importance: Therapies that improve survival in critically ill patients with coronavirus disease 2019 (COVID-19) are needed. Tocilizumab, a monoclonal antibody against the interleukin 6 receptor, may counteract the inflammatory cytokine release syndrome in patients with severe COVID-19 illness. Objective: To test whether tocilizumab decreases mortality in this population. Design, Setting, and Participants: The data for this study were derived from a multicenter cohort study of 4485 adults with COVID-19 admitted to participating intensive care units (ICUs) at 68 hospitals across the US from March 4 to May 10, 2020. Critically ill adults with COVID-19 were categorized according to whether they received or did not receive tocilizumab in the first 2 days of admission to the ICU. Data were collected retrospectively until June 12, 2020. A Cox regression model with inverse probability weighting was used to adjust for confounding. Exposures: Treatment with tocilizumab in the first 2 days of ICU admission. Main Outcomes and Measures: Time to death, compared via hazard ratios (HRs), and 30-day mortality, compared via risk differences. Results: Among the 3924 patients included in the analysis (2464 male [62.8%]; median age, 62 [interquartile range {IQR}, 52-71] years), 433 (11.0%) received tocilizumab in the first 2 days of ICU admission. Patients treated with tocilizumab were younger (median age, 58 [IQR, 48-65] vs 63 [IQR, 52-72] years) and had a higher prevalence of hypoxemia on ICU admission (205 of 433 [47.3%] vs 1322 of 3491 [37.9%] with mechanical ventilation and a ratio of partial pressure of arterial oxygen to fraction of inspired oxygen of <200 mm Hg) than patients not treated with tocilizumab. After applying inverse probability weighting, baseline and severity-of-illness characteristics were well balanced between groups. A total of 1544 patients (39.3%) died, including 125 (28.9%) treated with tocilizumab and 1419 (40.6%) not treated with tocilizumab. In the primary analysis, during a median follow-up of 27 (IQR, 14-37) days, patients treated with tocilizumab had a lower risk of death compared with those not treated with tocilizumab (HR, 0.71; 95% CI, 0.56-0.92). The estimated 30-day mortality was 27.5% (95% CI, 21.2%-33.8%) in the tocilizumab-treated patients and 37.1% (95% CI, 35.5%-38.7%) in the non-tocilizumab-treated patients (risk difference, 9.6%; 95% CI, 3.1%-16.0%). Conclusions and Relevance: Among critically ill patients with COVID-19 in this cohort study, the risk of in-hospital mortality in this study was lower in patients treated with tocilizumab in the first 2 days of ICU admission compared with patients whose treatment did not include early use of tocilizumab. However, the findings may be susceptible to unmeasured confounding, and further research from randomized clinical trials is needed.

Bone Morphogenetic Protein 9 Is a Mechanistic Biomarker of Portopulmonary Hypertension.

RATIONALE: BMP9 (bone morphogenetic protein 9) is a circulating endothelial quiescence factor with protective effects in pulmonary arterial hypertension (PAH). Loss-of-function mutations in BMP9, its receptors, and downstream effectors have been reported in heritable PAH. OBJECTIVES: To determine how an acquired deficiency of BMP9 signaling might contribute to PAH. METHODS: Plasma levels of BMP9 and antagonist soluble endoglin were measured in group 1 PAH, group 2 and 3 pulmonary hypertension (PH), and in patients with severe liver disease without PAH. MEASUREMENTS AND MAIN RESULTS: BMP9 levels were markedly lower in portopulmonary hypertension (PoPH) versus healthy control subjects, or other etiologies of PAH or PH; distinguished PoPH from patients with liver disease without PAH; and were an independent predictor of transplant-free survival. BMP9 levels were decreased in mice with PH associated with CCl4-induced portal hypertension and liver cirrhosis, but were normal in other rodent models of PH. Administration of ALK1-Fc, a BMP9 ligand trap consisting of the activin receptor-like kinase-1 extracellular domain, exacerbated PH and pulmonary vascular remodeling in mice treated with hypoxia versus hypoxia alone. CONCLUSIONS: BMP9 is a sensitive and specific biomarker of PoPH, predicting transplant-free survival and the presence of PAH in liver disease. In rodent models, acquired deficiency of BMP9 signaling can predispose to or exacerbate PH, providing a possible mechanistic link between PoPH and heritable PAH. These findings describe a novel experimental model of severe PH that provides insight into the synergy between pulmonary vascular injury and diminished BMP9 signaling in the pathogenesis of PAH.