Racial and ethnic disparities in mortality from acute lung injury

Race and Ethnicity Disparities in Management and Outcomes of Critically Ill Adults with Acute Respiratory Failure

This article reviews the current evidence base for racial and ethnic disparities related to acute respiratory failure. It discusses the prevailing and most studied mechanisms that underlay these disparities, analytical challenges that face the field, and then uses this discussion to frame future directions to outline next steps for developing disparities-mitigating solutions.

Ethnic Disparities in Deep Sedation of Patients with Acute Respiratory Distress Syndrome in the United States: Secondary Analysis of a Multicenter Randomized Trial

Rationale: Patients identified as Hispanic, the largest minority group in the United States, are more likely to die from acute respiratory distress syndrome (ARDS) than non-Hispanic patients. Mechanisms to explain this disparity remain unidentified. However, Hispanic patients may be at risk of overexposure to deep sedation because of language differences between patients and clinicians, and deep sedation is associated with higher ARDS mortality.Objective: We examined associations between Hispanic ethnicity and exposure to deep sedation among patients with ARDS.Methods: A secondary analysis was conducted of patients enrolled in the control arm of a randomized trial of neuromuscular blockade for ARDS across 48 U.S. hospitals. Exposure to deep sedation was measured over the first 5 days that a patient was alive and received mechanical ventilation. Multilevel mixed-effects models were used to evaluate associations between Hispanic ethnicity and exposure to deep sedation, controlling for patient characteristics.Results: Patients identified as Hispanic had approximately five times the odds of deep sedation (odds ratio, 4.98; 95% confidence interval, 2.02-12.28; P < 0.0001) on a given day, compared with non-Hispanic White patients. Hospitals with at least one enrolled Hispanic patient kept all enrolled patients deeply sedated longer than hospitals without any enrolled Hispanic patients (85.8% of ventilator-days vs. 65.5%; P < 0.001).Conclusions: Hispanic patients are at higher risk of exposure to deep sedation than non-Hispanic White patients. There is an urgent need to understand and address disparities in sedation delivery.

Association between Patient Race and Ethnicity and Use of Invasive Ventilation in the United States

Rationale: Outcomes for people with respiratory failure in the United States vary by patient race and ethnicity. Invasive ventilation is an important treatment initiated based on expert opinion. It is unknown whether the use of invasive ventilation varies by patient race and ethnicity. Objectives: To measure 1) the association between patient race and ethnicity and the use of invasive ventilation; and 2) the change in 28-day mortality mediated by any association. Methods: We performed a multicenter cohort study of nonintubated adults receiving oxygen within 24 hours of intensive care admission using the Medical Information Mart for Intensive Care IV (MIMIC-IV, 2008-2019) and Phillips eICU (eICU, 2014-2015) databases from the United States. We modeled the association between patient race and ethnicity (Asian, Black, Hispanic, White) and invasive ventilation rate using a Bayesian multistate model that adjusted for baseline and time-varying covariates, calculated hazard ratios (HRs), and estimated 28-day hospital mortality changes mediated by differential invasive ventilation use. We reported posterior means and 95% credible intervals (CrIs). Results: We studied 38,258 patients, 52% (20,032) from MIMIC-IV and 48% (18,226) from eICU: 2% Asian (892), 11% Black (4,289), 5% Hispanic (1,964), and 81% White (31,113). Invasive ventilation occurred in 9.2% (3,511), and 7.5% (2,869) died. The adjusted rate of invasive ventilation was lower in Asian (HR, 0.82; CrI, 0.70-0.95), Black (HR, 0.78; CrI, 0.71-0.86), and Hispanic (HR, 0.70; CrI, 0.61-0.79) patients compared with White patients. For the average patient, lower rates of invasive ventilation did not mediate differences in 28-day mortality. For a patient on high-flow nasal cannula with inspired oxygen fraction of 1.0, the odds ratios for mortality if invasive ventilation rates were equal to the rate for White patients were 0.97 (CrI, 0.91-1.03) for Asian patients, 0.96 (CrI, 0.91-1.03) for Black patients, and 0.94 (CrI, 0.89-1.01) for Hispanic patients. Conclusions: Asian, Black, and Hispanic patients had lower rates of invasive ventilation than White patients. These decreases did not mediate harm for the average patient, but we could not rule out harm for patients with more severe hypoxemia.

Racial disparities among patients on venovenous extracorporeal membrane oxygenation in the pre-Coronavirus Disease 2019 and Coronavirus Disease 2019 eras: A retrospective registry review

Objectives

Although many studies have addressed such disparities caused by COVID-19, to our knowledge, no study has focused on the association of race on outcomes for patients with COVID-19 requiring venovenous extracorporeal membrane oxygenation support. The goal of this study was to assess association of race on death and duration on venovenous extracorporeal membrane oxygenation in both the pre-COVID-19 and COVID-19 eras.

Methods

We retrospectively reviewed the Extracorporeal Life Support Organization registry and included adults (≥18 years) who required venovenous extracorporeal membrane oxygenation between January 2019 and April 2021. We performed descriptive statistics and multivariable logistic regression. Our primary outcomes were death and extracorporeal membrane oxygenation duration.

Results

A total of 7477 patients were included after excluding 340 patients (4.3%) who were missing race data. In the COVID-19 era, 1474 of 2777 COVID-19-positive patients (53.1%) died. Our regression model suggested somewhat of a protective effect on death for Black and multiple race patients. Additionally, a diagnosis of COVID-19 and patients in the COVID-19 era in general, irrespective of COVID-19 diagnosis, had higher odds of death. Hispanic patients had the longest average venovenous extracorporeal membrane oxygenation run times.

Conclusions

Our study using data from the international Extracorporeal Life Support Organization Registry provides updated data on patients supported with venovenous extracorporeal membrane oxygenation in the pre-COVID-19 and COVID-19 eras between 2019 and 2021 with a focus on race. Patients in the COVID-19 era group also had higher mortality compared with those in the pre-COVID-19 era even after being adjusted for COVID-19 diagnosis. Black and multiple races appeared somewhat protective in terms of death. Hispanic race was associated with longer venovenous extracorporeal membrane oxygenation duration.

Racial and Ethnic Disparities in Veno-Venous Extracorporeal Membrane Oxygenation Mortality for Patients With Severe COVID-19

Racial/ethnic disparities in mortality were observed during the coronavirus disease-2019 pandemic, but investigations examining the association between race/ethnicity and mortality during extracorporeal membrane oxygenation (ECMO) are limited. We performed a retrospective observational cohort study using the 2020 national inpatient sample. Multivariable logistic regression was used to estimate the odds of mortality in patients of difference race/ethnicity while controlling for confounders. There was a significant association between race/ethnicity and in-hospital mortality ( p < 0.001). Hispanic patients had significantly higher in-hospital mortality compared with White patients (odds ratio [OR] = 1.39, 95% confidence interval [CI] = 1.16-1.67, p < 0.001). Black patients and patients of other races did not have significantly higher in-hospital mortality compared with White patients (OR = 0.82, 95% CI = 0.66-1.02, p = 0.07 and OR = 1.20, 95% CI = 0.92-1.57, p = 0.18). Other variables that had a significant association with mortality included age, insurance type, Charlson comorbidity index, all patient-refined severity of illness, and receipt of care in a low-volume ECMO center (all p < 0.001). Further studies are needed to understand causes of disparities in ECMO mortality.

Racial and ethnic minority participants in clinical trials of acute respiratory distress syndrome

PURPOSE

There is growing interest in improving the inclusiveness of racial and ethnic minority participants in trials of acute respiratory distress syndrome (ARDS). With our study we aimed to examine temporal trends of representation and mortality of racial and ethnic minority participants in randomized controlled trials of ARDS.

METHODS

We performed a secondary analysis of eight ARDS Network and PETAL Network therapeutic clinical trials, published between 2000 and 2019. We classified race/ethnicity into "White", "Black", "Hispanic", or "Other" (including Asian, American Indian or Alaskan Native, Native Hawaiian, or other Pacific Islander participants).

RESULTS

Of 5375 participants with ARDS, 1634 (30.4%) were Black, Hispanic, or Other race participants. Representation of racial and ethnic minority participants in trials did not change significantly over time (p = 0.257). However, among participants with moderate to severe ARDS (i.e., partial pressure of arterial oxygen to fraction of inspired oxygen ratio < 150), the difference in mortality between racial and ethnic minority participants and White participants decreased over time. In the five most recent trials, including 2923 participants with ARDS, there were no statistically significant differences in mortality between racial/ethnic groups, even after adjusting for potential confounders. In these five most recent trials, mortality was 31% for White, 31.9% for Black, 30.3% for Hispanic, and 37.1% for Other race participants (p = 0.633).

CONCLUSION

Representation of racial and ethnic minority participants in ARDS trials from North America, published between 2000 and 2019, did not change over time. Black and Hispanic participants with ARDS may have similar mortality as White participants within trials.

Genetic Determinants of the Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that arises from multiple causes, including sepsis, pneumonia, trauma, and severe coronavirus disease 2019 (COVID-19). Given the heterogeneity of causes and the lack of specific therapeutic options, it is crucial to understand the genetic and molecular mechanisms that underlie this condition. The identification of genetic risks and pharmacogenetic loci, which are involved in determining drug responses, could help enhance early patient diagnosis, assist in risk stratification of patients, and reveal novel targets for pharmacological interventions, including possibilities for drug repositioning. Here, we highlight the basis and importance of the most common genetic approaches to understanding the pathogenesis of ARDS and its critical triggers. We summarize the findings of screening common genetic variation via genome-wide association studies and analyses based on other approaches, such as polygenic risk scores, multi-trait analyses, or Mendelian randomization studies. We also provide an overview of results from rare genetic variation studies using Next-Generation Sequencing techniques and their links with inborn errors of immunity. Lastly, we discuss the genetic overlap between severe COVID-19 and ARDS by other causes.

Racial Disparities in Length of Stay Among Severely Ill Patients Presenting With Sepsis and Acute Respiratory Failure

Importance

Although racial and ethnic minority patients with sepsis and acute respiratory failure (ARF) experience worse outcomes, how patient presentation characteristics, processes of care, and hospital resource delivery are associated with outcomes is not well understood.

Objective

To measure disparities in hospital length of stay (LOS) among patients at high risk of adverse outcomes who present with sepsis and/or ARF and do not immediately require life support and to quantify associations with patient- and hospital-level factors.

Design, Setting, and Participants

This matched retrospective cohort study used electronic health record data from 27 acute care teaching and community hospitals across the Philadelphia metropolitan and northern California areas between January 1, 2013, and December 31, 2018. Matching analyses were performed between June 1 and July 31, 2022. The study included 102 362 adult patients who met clinical criteria for sepsis (n = 84 685) or ARF (n = 42 008) with a high risk of death at the time of presentation to the emergency department but without an immediate requirement for invasive life support.

Exposures

Racial or ethnic minority self-identification.

Main Outcomes and Measures

Hospital LOS, defined as the time from hospital admission to the time of discharge or inpatient death. Matches were stratified by racial and ethnic minority patient identity, comparing Asian and Pacific Islander patients, Black patients, Hispanic patients, and multiracial patients with White patients in stratified analyses.

Results

Among 102 362 patients, the median (IQR) age was 76 (65-85) years; 51.5% were male. A total of 10.2% of patients self-identified as Asian American or Pacific Islander, 13.7% as Black, 9.7% as Hispanic, 60.7% as White, and 5.7% as multiracial. After matching racial and ethnic minority patients to White patients on clinical presentation characteristics, hospital capacity strain, initial intensive care unit admission, and the occurrence of inpatient death, Black patients experienced longer LOS relative to White patients in fully adjusted matches (sepsis: 1.26 [95% CI, 0.68-1.84] days; ARF: 0.97 [95% CI, 0.05-1.89] days). Length of stay was shorter among Asian American and Pacific Islander patients with ARF (-0.61 [95% CI, -0.88 to -0.34] days) and Hispanic patients with sepsis (-0.22 [95% CI, -0.39 to -0.05] days) or ARF (-0.47 [-0.73 to -0.20] days).

Conclusions and Relevance

In this cohort study, Black patients with severe illness who presented with sepsis and/or ARF experienced longer LOS than White patients. Hispanic patients with sepsis and Asian American and Pacific Islander and Hispanic patients with ARF both experienced shorter LOS. Because matched differences were independent of commonly implicated clinical presentation-related factors associated with disparities, identification of additional mechanisms that underlie these disparities is warranted.

Differential pulse oximetry readings between ethnic groups and delayed transfer to intensive care units

BACKGROUND

Pulse oximeters are widely used to monitor blood oxygen saturations, although concerns exist that they are less accurate in individuals with pigmented skin.

AIMS

This study aimed to determine if patients with pigmented skin were more severely unwell at the period of transfer to intensive care units (ICUs) than individuals with White skin.

METHODS

Using data from a large teaching hospital, measures of clinical severity at the time of transfer of patients with COVID-19 infection to ICUs were assessed, and how this varied by ethnic group.

RESULTS

Data were available on 748 adults. Median pulse oximetry demonstrated similar oxygen saturations at the time of transfer to ICUs (Kruskal-Wallis test, P = 0.51), although median oxygen saturation measurements from arterial blood gases at this time demonstrated lower oxygen saturations in patients classified as Indian/Pakistani ethnicity (91.6%) and Black/Mixed ethnicity (93.0%), compared to those classified as a White ethnicity (94.4%, Kruskal-Wallis test, P = 0.005). There were significant differences in mean respiratory rates in these patients (P < 0.0001), ranging from 26 breaths/min in individuals with White ethnicity to 30 breaths/min for those classified as Indian/Pakistani ethnicity and 31 for those who were classified as Black/Mixed ethnicity.

CONCLUSIONS

These data are consistent with the hypothesis that differential measurement error for pulse oximeter readings negatively impact on the escalation of clinical care in individuals from other than White ethnic groups. This has implications for healthcare in Africa and South-East Asia and may contribute to differences in health outcomes across ethnic groups globally.

Leveraging Clinical Informatics and Data Science to Improve Care and Facilitate Research in Pediatric Acute Respiratory Distress Syndrome: From the Second Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

The use of electronic algorithms, clinical decision support systems, and other clinical informatics interventions is increasing in critical care. Pediatric acute respiratory distress syndrome (PARDS) is a complex, dynamic condition associated with large amounts of clinical data and frequent decisions at the bedside. Novel data-driven technologies that can help screen, prompt, and support clinician decision-making could have a significant impact on patient outcomes. We sought to identify and summarize relevant evidence related to clinical informatics interventions in both PARDS and adult respiratory distress syndrome (ARDS), for the second Pediatric Acute Lung Injury Consensus Conference.

DATA SOURCES

MEDLINE (Ovid), Embase (Elsevier), and CINAHL Complete (EBSCOhost).

STUDY SELECTION

We included studies of pediatric or adult critically ill patients with or at risk of ARDS that examined automated screening tools, electronic algorithms, or clinical decision support systems.

DATA EXTRACTION

Title/abstract review, full text review, and data extraction using a standardized data extraction form.

DATA SYNTHESIS

The Grading of Recommendations Assessment, Development and Evaluation approach was used to identify and summarize evidence and develop recommendations. Twenty-six studies were identified for full text extraction to address the Patient/Intervention/Comparator/Outcome questions, and 14 were used for the recommendations/statements. Two clinical recommendations were generated, related to the use of electronic screening tools and automated monitoring of compliance with best practice guidelines. Two research statements were generated, related to the development of multicenter data collaborations and the design of generalizable algorithms and electronic tools. One policy statement was generated, related to the provision of material and human resources by healthcare organizations to empower clinicians to develop clinical informatics interventions to improve the care of patients with PARDS.

CONCLUSIONS

We present two clinical recommendations and three statements (two research one policy) for the use of electronic algorithms and clinical informatics tools for patients with PARDS based on a systematic review of the literature and expert consensus.

Linkage of NAMPT promoter variants to eNAMPT secretion, plasma eNAMPT levels, and ARDS severity

BACKGROUND AND OBJECTIVES

eNAMPT (extracellular nicotinamide phosphoribosyltransferase), a novel DAMP and TLR4 ligand, is a druggable ARDS therapeutic target with NAMPT promoter SNPs associated with ARDS severity. This study assesses the previously unknown influence of NAMPT promoter SNPs on NAMPT transcription, eNAMPT secretion, and ARDS severity.

METHODS AND DESIGN

Human lung endothelial cells (ECs) transfected with NAMPT promoter luciferase reporters harboring SNPs G-1535A, A-1001 C, and C-948A, were exposed to LPS or LPS/18% cyclic stretch (CS) and NAMPT promoter activity, NAMPT protein expression, and secretion assessed. NAMPT genotypes and eNAMPT plasma measurements (Days 0/7) were assessed in two ARDS cohorts (DISCOVERY n = 428; ALVEOLI n = 103).

RESULTS

Comparisons of minor allelic frequency (MAF) in both ARDS cohorts with the 1000 Human Genome Project revealed the G-1535A and C-948A SNPs to be significantly associated with ARDS in Blacks compared with controls and trended toward significance in non-Hispanic Whites. LPS-challenged and LPS/18% CS-challenged EC harboring the -1535G wild-type allele exhibited significantly increased NAMPT promoter activity (compared with -1535A) with the -1535G/-948A diplotype exhibiting significantly increased NAMPT promoter activity, NAMPT protein expression, and eNAMPT secretion compared with the -1535A/-948 C diplotype. Highly significant increases in Day 0 eNAMPT plasma values were observed in both DISCOVERY and ALVEOLI ARDS cohorts (compared with healthy controls). Among subjects surviving to Day 7, Day 7 eNAMPT values were significantly increased in Day 28 non-survivors versus survivors. The protective -1535A SNP allele drove -1535A/-1001A and -1535A/-948 C diplotypes that confer significantly reduced ARDS risk (compared with -1535G, -1535G/-1001 C, -1535G/-948A), particularly in Black ARDS subjects. NAMPT SNP comparisons within the two ARDS cohorts did not identify significant association with either APACHE III scores or plasma eNAMPT levels.

CONCLUSION

NAMPT SNPs influence promoter activity, eNAMPT protein expression/secretion, plasma eNAMPT levels, and ARDS severity. NAMPT genotypes are a potential tool for stratification in eNAMPT-focused ARDS clinical trials.

Association of surfactant protein A2 with acute respiratory failure in children

BACKGROUND

Interactions among single nucleotide polymorphisms (SNPs) of surfactant protein (SP) are associated with acute respiratory failure (ARF) and its short-term outcome, pulmonary dysfunction at discharge (PDAD) in children. However, genetic association studies using individual SNPs have not been conducted before. We hypothesize that SP genetic variants are associated with pediatric ARF and its short-term complications by themselves.

METHODS

We used available genotype and clinical data in the Floros biobank consisting of 248 children aged ≤24 months with ARF; 86 developed PDAD. A logistic regression analysis was performed for each of the 14 selected SNPs, SP-A1 and SP-A2 genotypes. A p-value less than the Bonferroni correction threshold was considered significant. A likelihood ratio test was done to compare two models (one with demographic data and another with genetic variants).

RESULTS

Before Bonferroni correction, female sex is associated with a decreased risk of ARF. Black race and the rs721917 of the SFTPD are associated with increased risk of ARF. After Bonferroni correction, the 1A0 1A1 genotype of SFTPA2 was associated with decreased risk of ARF. The likelihood ratio test showed that the model of the genotype information with demographic data was a better fit to predict ARF risk. None of the SP SNPs and SP-A1, SP-A2 genotypes were associated with PDAD.

CONCLUSION

Our results indicate that SNPs and genotypes of SPs involved in innate immunity and host defense play an important role in ARF and, in the future, may be used as biomarkers.

Pulse oximetry for the diagnosis and management of acute respiratory distress syndrome

The diagnosis of acute respiratory distress syndrome (ARDS) traditionally requires calculation of the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) using arterial blood, which can be costly and is not possible in many resource-limited settings. By contrast, pulse oximetry is continuously available, accurate, inexpensive, and non-invasive. Pulse oximetry-based indices, such as the ratio of pulse-oximetric oxygen saturation to FiO2 (SpO2/FiO2), have been validated in clinical studies for the diagnosis and risk stratification of patients with ARDS. Limitations of the SpO2/FiO2 ratio include reduced accuracy in poor perfusion states or above oxygen saturations of 97%, and the potential for reduced accuracy in patients with darker skin pigmentation. Application of pulse oximetry to the diagnosis and management of ARDS, including formal adoption of the SpO2/FiO2 ratio as an alternative to PaO2/FiO2 to meet the diagnostic criterion for hypoxaemia in ARDS, could facilitate increased and earlier recognition of ARDS worldwide to advance both clinical practice and research.

Opportunities for improved clinical trial designs in acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a common critical illness syndrome with high morbidity and mortality. There are no proven pharmacological therapies for ARDS. The current definition of ARDS is based on shared clinical characteristics but does not capture the heterogeneity in clinical risk factors, imaging characteristics, physiology, timing of onset and trajectory, and biology of the syndrome. There is increasing interest within the ARDS clinical trialist community to design clinical trials that reduce heterogeneity in the trial population. This effort must be balanced with ongoing work to craft an inclusive, global definition of ARDS, with important implications for trial design. Ultimately, the two aims-to design trials that are applicable to the diverse global ARDS population while also advancing opportunities to identify targetable traits-should coexist. In this Personal View, we recommend two primary strategies to improve future ARDS trials: the development of new methods to target treatable traits in clinical trial populations, and improvements in the representativeness of ARDS trials, with the inclusion of global populations. We emphasise that these two strategies are complementary. We also discuss how a proposed expansion of the definition of ARDS could affect the future of clinical trials.

Absolute quantification of plasma mitochondrial DNA by droplet digital PCR marks COVID-19 severity over time during intensive care unit admissions

Increased plasma mitochondrial DNA concentrations are associated with poor outcomes in multiple critical illnesses, including COVID-19. However, current methods of cell-free mitochondrial DNA quantification in plasma are time-consuming and lack reproducibility. Here, we used next-generation sequencing to characterize the size and genome location of circulating mitochondrial DNA in critically ill subjects with COVID-19 to develop a facile and optimal method of quantification by droplet digital PCR. Sequencing revealed a large percentage of small mitochondrial DNA fragments in plasma with wide variability in coverage by genome location. We identified probes for the mitochondrial DNA genes, cytochrome B and NADH dehydrogenase 1, in regions of relatively high coverage that target small sequences potentially missed by other methods. Serial assessments of absolute mitochondrial DNA concentrations were then determined in plasma from 20 critically ill subjects with COVID-19 without a DNA isolation step. Mitochondrial DNA concentrations on the day of enrollment were increased significantly in patients with moderate or severe acute respiratory distress syndrome (ARDS) compared with those with no or mild ARDS. Comparisons of mitochondrial DNA concentrations over time between patients with no/mild ARDS who survived, patients with moderate/severe ARDS who survived, and nonsurvivors showed the highest concentrations in patients with more severe disease. Absolute mitochondrial DNA quantification by droplet digital PCR is time-efficient and reproducible; thus, we provide a valuable tool and rationale for future studies evaluating mitochondrial DNA as a real-time biomarker to guide clinical decision-making in critically ill subjects with COVID-19.

A cortactin CTTN coding SNP contributes to lung vascular permeability and inflammatory disease severity in African descent subjects

The cortactin gene (CTTN), encoding an actin-binding protein critically involved in cytoskeletal dynamics and endothelial cell (EC) barrier integrity, contains single nucleotide polymorphisms (SNPs) associated with severe asthma in Black patients. As loss of lung EC integrity is a major driver of mortality in the Acute Respiratory Distress Syndrome (ARDS), sepsis, and the acute chest syndrome (ACS), we speculated CTTN SNPs that alter EC barrier function will associate with clinical outcomes from these types of conditions in Black patients. In case-control studies, evaluation of a nonsynonymous CTTN coding SNP Ser484Asn (rs56162978, G/A) in a severe sepsis cohort (725 Black subjects) revealed significant association with increased risk of sepsis mortality. In a separate cohort of sickle cell disease (SCD) subjects with and without ACS (177 SCD Black subjects), significantly increased risk of ACS and increased ACS severity (need for mechanical ventilation) was observed in carriers of the A allele. Human lung EC expressing the cortactin S484N transgene exhibited: (i) delayed EC barrier recovery following thrombin-induced permeability; (ii) reduced levels of critical Tyr486 cortactin phosphorylation; (iii) inhibited binding to the cytoskeletal regulator, nmMLCK; and (iv) attenuated EC barrier-promoting lamellipodia dynamics and biophysical responses. ARDS-challenged Cttn+/- heterozygous mice exhibited increased lung vascular permeability (compared to wild-type mice) which was significantly attenuated by IV delivery of liposomes encargoed with CTTN WT transgene but not by CTTN S484N transgene. In summary, these studies suggest that the CTTN S484N coding SNP contributes to severity of inflammatory injury in Black patients, potentially via delayed vascular barrier restoration.

Racial Disparities in ICU Outcomes: A Systematic Review

OBJECTIVES

Racial disparities in the United States healthcare system are well described across a variety of clinical settings. The ICU is a clinical environment with a higher acuity and mortality rate, potentially compounding the impact of disparities on patients. We sought to systematically analyze the literature to assess the prevalence of racial disparities in the ICU.

DATA SOURCES

We conducted a comprehensive search of PubMed/MEDLINE, Scopus, CINAHL, and the Cochrane Library.

STUDY SELECTION

We identified articles that evaluated racial differences on outcomes among ICU patients in the United States. Two authors independently screened and selected articles for inclusion.

DATA EXTRACTION

We dual-extracted study characteristics and outcomes that assessed for disparities in care (e.g., in-hospital mortality, ICU length of stay). Studies were assessed for bias using the Newcastle-Ottawa Scale.

DATA SYNTHESIS

Of 1,325 articles screened, 25 articles were included (n = 751,796 patients). Studies demonstrated race-based differences in outcomes, including higher mortality rates for Black patients when compared with White patients. However, when controlling for confounding variables, such as severity of illness and hospital type, mortality differences based on race were no longer observed. Additionally, results revealed that Black patients experienced greater financial impacts during an ICU admission, were less likely to receive early tracheostomy, and were less likely to receive timely antibiotics than White patients. Many studies also observed differences in patients' end-of-life care, including lower rates on the quality of dying, less advanced care planning, and higher intensity of interventions at the end of life for Black patients.

CONCLUSIONS

This systematic review found significant differences in the care and outcomes among ICU patients of different races. Mortality differences were largely explained by accompanying demographic and patient factors, highlighting the effect of structural inequalities on racial differences in mortality in the ICU. This systematic review provides evidence that structural inequalities in care persist in the ICU, which contribute to racial disparities in care. Future research should evaluate interventions to address inequality in the ICU.

Prognostic factors for development of acute respiratory distress syndrome following traumatic injury - a systematic review and meta-analysis

PURPOSE

To summarise the prognostic associations between various clinical risk factors and the development of the acute respiratory distress syndrome (ARDS) following traumatic injury.

METHODS

We conducted this review in accordance with the PRISMA and CHARMS guidelines. We searched six databases from inception through December 2020. We included English language studies describing the clinical risk factors associated with the development of post-traumatic ARDS, as defined by either the American-European Consensus Conference or the Berlin definition. We pooled adjusted odds ratios for prognostic factors using the random effects method. We assessed risk of bias using the QUIPS tool and certainty of findings using GRADE methodology.

RESULTS

We included 39 studies involving 5 350 927 patients. We identified the amount of crystalloid resuscitation as a potentially modifiable prognostic factor associated with the development of post-traumatic ARDS (adjusted odds ratio [aOR] 1.19 for each additional liter of crystalloid administered within first 6 h after injury, 95% CI 1.15 to 1.24, high certainty). Non-modifiable prognostic factors with a moderate or high certainty of association with post-traumatic ARDS included increasing age, non-Hispanic white race, blunt mechanism of injury, presence of head injury, pulmonary contusion, or rib fracture; and increasing chest injury severity.

CONCLUSION

We identified one important modifiable factor, the amount of crystalloid resuscitation within the first 24 h of injury, and several non-modifiable factors associated with development of post-traumatic ARDS. This information should support the judicious use of crystalloid resuscitation in trauma patients and may inform the development of a risk-stratification tools.

Sex-dependent acrolein sensitivity in mice is associated with differential lung cell, protein, and transcript changes

Acrolein is a reactive inhalation hazard. Acrolein's initial interaction, which in itself can be function-altering, is followed by time-dependent cascade of complex cellular and pulmonary responses that dictate the severity of the injury. To investigate the pathophysiological progression of sex-dependent acrolein-induced acute lung injury, C57BL/6J mice were exposed for 30 min to sublethal, but toxic, and lethal acrolein. Male mice were more sensitive than female mice. Acrolein of 50 ppm was sublethal to female but lethal to male mice, and 75 ppm was lethal to female mice. Lethal and sublethal acrolein exposure decreased bronchoalveolar lavage (BAL) total cell number at 3 h after exposure. The cell number decrease was followed by progressive total cell and neutrophil number and protein increases. The BAL total cell number in female mice exposed to a sublethal, but not lethal dose, returned to control levels at 16 h. In contrast, BAL protein content and neutrophil number were higher in mice exposed to lethal compared to sublethal acrolein. RNASeq pathway analysis identified greater increased lung neutrophil, glutathione metabolism, oxidative stress responses, and CCL7 (aka MCP-3), CXCL10 (aka IP-10), and IL6 transcripts in males than females, whereas IL10 increased more in female than male mice. Thus, the IL6:IL10 ratio, an indicator of disease severity, was greater in males than females. Further, H3.3 histone B (H3F3B) and pro-platelet basic protein (PPBP aka CXCL7), transcripts increased in acrolein exposed mouse BAL and plasma at 3 h, while H3F3B protein that is associated with neutrophil extracellular traps formation increased at 12 h. These results suggest that H3F3B and PPBP transcripts increase may contribute to extracellular H3F3B and PPBP proteins increase.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute respiratory illness characterised by bilateral chest radiographical opacities with severe hypoxaemia due to non-cardiogenic pulmonary oedema. The COVID-19 pandemic has caused an increase in ARDS and highlighted challenges associated with this syndrome, including its unacceptably high mortality and the lack of effective pharmacotherapy. In this Seminar, we summarise current knowledge regarding ARDS epidemiology and risk factors, differential diagnosis, and evidence-based clinical management of both mechanical ventilation and supportive care, and discuss areas of controversy and ongoing research. Although the Seminar focuses on ARDS due to any cause, we also consider commonalities and distinctions of COVID-19-associated ARDS compared with ARDS from other causes.

Comorbidities, sequelae, blood biomarkers and their associated clinical outcomes in the Mount Sinai Health System COVID-19 patients

With the continuing rise of SARS-CoV2 infection globally and the emergence of various waves in different countries, understanding characteristics of susceptibility to infection, clinical severity, and outcomes remain vital. In this retrospective study, data was extracted for 39,539 patients from the de-identified Mount Sinai Health System COVID-19 database. We assessed the risk of mortality based on the presence of comorbidities and organ-specific sequelae in 7,032 CoV2 positive (+) patients. Prevalence of cardiovascular and metabolic comorbidities was high among SARS-CoV2+ individuals. Diabetes, obesity, coronary artery disease, hypertension, atrial fibrillation, and heart failure all increased overall mortality risk, while asthma did not. Ethnicity modified the risk of mortality associated with these comorbidities. With regards to secondary complications in the setting of infection, individuals with acute kidney injury and acute myocardial injury showed an increase in mortality risk. Cerebral infarcts and acute venous thromboembolic events were not associated with increased risk of mortality. Biomarkers for cardiovascular injury, coagulation, and inflammation were compared between deceased and survived individuals. We found that cardiac and coagulation biomarkers were elevated and fell beyond normal range more often in deceased patients. Several, but not all, inflammatory markers evaluated were increased in deceased patients. In summary, we identified comorbidities and sequelae along with peripheral blood biomarkers that were associated with elevated clinical severity and poor outcomes in COVID-19 patients. Overall, these findings detail the granularity of previously reported factors which may impact susceptibility, clinical severity, and mortality during the course of COVID-19 disease.

Strategies to DAMPen COVID-19-mediated lung and systemic inflammation and vascular injury

Approximately 15%-20% of patients infected with SARS-CoV-2 coronavirus (COVID-19) progress beyond mild and self-limited disease to require supplemental oxygen for severe pneumonia; 5% of COVID-19-infected patients further develop acute respiratory distress syndrome (ARDS) and multiorgan failure. Despite mortality rates surpassing 40%, key insights into COVID-19-induced ARDS pathology have not been fully elucidated and multiple unmet needs remain. This review focuses on the unmet need for effective therapies that target unchecked innate immunity-driven inflammation which drives unchecked vascular permeability, multiorgan dysfunction and ARDS mortality. Additional unmet needs including the lack of insights into factors predicting pathogenic hyperinflammatory viral host responses, limited approaches to address the vast disease heterogeneity in ARDS, and the absence of clinically-useful ARDS biomarkers. We review unmet needs persisting in COVID-19-induced ARDS in the context of the potential role for damage-associated molecular pattern proteins in lung and systemic hyperinflammatory host responses to SARS-CoV-2 infection that ultimately drive multiorgan dysfunction and ARDS mortality. Insights into promising stratification-enhancing, biomarker-based strategies in COVID-19 and non-COVID ARDS may enable the design of successful clinical trials of promising therapies.

Nucleotide polymorphism in ARDS outcome: a whole exome sequencing association study

Background

Genetic locus were identified associated with acute respiratory distress syndrome (ARDS). Our goal was to explore the associations between genetic variants and ARDS outcome, as well as subphenotypes.

Methods

This was a single-center, prospective observational trial enrolling adult ARDS patients. After baseline data were collected, blood samples were drawn to perform whole exome sequencing, single nucleotide polymorphism (SNP)/insertion-deletion to explore the quantitative and functional associations between genetic variants and ICU outcome, clinical subphenotypes. Then the lung injury burden (LIB), which was defined as the ratio of nonsynonymous SNP number per megabase of DNA, was used to evaluate its value in predicting ARDS outcome.

Results

A total of 105 ARDS patients were enrolled in the study, including 70 survivors and 35 nonsurvivors. Based on the analysis of a total of 65,542 nonsynonymous SNP, LIB in survivors was significantly higher than nonsurvivors [1,892 (1,848–1,942)/MB versus 1,864 (1,829–1,910)/MB, P=0.018], while GO analysis showed that 60 functions were correlated with ARDS outcome, KEGG enrichment analysis showed that SNP/InDels were enriched in 13 pathways. Several new SNPs were found potentially associated with ARDS outcome. Analysis of LIB was used to determine its outcome predicting ability, the area under the ROC curve of which was only 0.6103, and increase to 0.712 when combined with APACHE II score.

Conclusions

Genetic variants are associated with ARDS outcome and subphenotypes; however, their prognostic value still need to be verified by larger trials.

Trial registration

Clinicaltrials.gov NCT02644798. Registered 20 April 2015.

Genetic and epigenetic regulation of the non-muscle myosin light chain kinase isoform by lung inflammatory factors and mechanical stress

RATIONALE

The myosin light chain kinase gene, MYLK, encodes three proteins via unique promoters, including the non-muscle isoform of myosin light chain kinase (nmMLCK), a cytoskeletal protein centrally involved in regulation of vascular integrity. As MYLK coding SNPs are associated with severe inflammatory disorders (asthma, acute respiratory distress syndrome (ARDS)), we explored clinically relevant inflammatory stimuli and promoter SNPs in nmMLCK promoter regulation.

METHODS

Full-length or serially deleted MYLK luciferase reporter promoter activities were measured in human lung endothelial cells (ECs). SNP-containing non-muscle MYLK (nmMYLK) DNA fragments were generated and nmMYLK promoter binding by transcription factors (TFs) detected by protein-DNA electrophoretic mobility shift assay (EMSA). Promoter demethylation was evaluated by 5-aza-2'-deoxycytidine (5-Aza). A preclinical mouse model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) was utilized for nmMLCK validation.

RESULTS

Lung EC levels of nmMLCK were significantly increased in LPS-challenged mice and LPS, tumor necrosis factor-α (TNF-α), 18% cyclic stretch (CS) and 5-Aza each significantly up-regulated EC nmMYLK promoter activities. EC exposure to FG-4592, a prolyl hydroxylase inhibitor that increases hypoxia-inducible factor (HIF) expression, increased nmMYLK promoter activity, confirmed by HIF1α/HIF2α silencing. nmMYLK promoter deletion studies identified distal inhibitory and proximal enhancing promoter regions as well as mechanical stretch-, LPS- and TNFα-inducible regions. Insertion of ARDS-associated SNPs (rs2700408, rs11714297) significantly increased nmMYLK promoter activity via increased transcription binding (glial cells missing homolog 1 (GCM1) and intestine-specific homeobox (ISX), respectively). Finally, the MYLK rs78755744 SNP (-261G/A), residing within a nmMYLK CpG island, significantly attenuated 5-Aza-induced promoter activity.

CONCLUSION

These findings indicate nmMYLK transcriptional regulation by clinically relevant inflammatory factors and ARDS-associated nmMYLK promoter variants are consistent with nmMLCK as a therapeutic target in severe inflammatory disorders.

Trends and Geographic Variation in Acute Respiratory Failure and ARDS Mortality in the United States

BACKGROUND

Despite numerous advances in the understanding of the pathophysiology, progression, and management of acute respiratory failure (ARF) and ARDS, limited contemporary data are available on the mortality burden of ARF and ARDS in the United States.

RESEARCH QUESTION

What are the contemporary trends and geographic variation in ARF and ARDS-related mortality in the United States?

STUDY DESIGN AND METHODS

A retrospective analysis of the National Center for Health Statistics' nationwide mortality data was conducted to assess the ARF and ARDS-related mortality trends from 2014 through 2018 and the geographic distribution of ARF and ARDS-related deaths in 2018 for all American residents. Piecewise linear regression was used to evaluate the trends in age-adjusted mortality rates (AAMRs) in the overall population and various demographic subgroups of age, sex, race, urbanization, and region.

RESULTS

Among 1,434,349 ARF-related deaths and 52,958 ARDS-related deaths during the study period, the AAMR was highest in older individuals (≥ 65 years), non-Hispanic Black people, and those living in the nonmetropolitan region. The AAMR for ARF-related deaths (per 100,000 people) increased from 74.9 (95% CI, 74.6-75.2) in 2014 to 85.6 (95% CI, 85.3-85.9) in 2018 (annual percentage change [APC], 3.4 [95% CI, 2.2-4.6]; Ptrend = .003). The AAMR (per 100,000 people) for ARDS-related deaths was 3.2 (95% CI, 3.2-3.3) in 2014 and 3.0 (95% CI, 3.0-3.1 in 2018; APC, -0.9 [95% CI, -5.4 to 3.8]; Ptrend = .56). The observed increase in rates for ARF mortality was consistent across the subgroups of age, sex, race or ethnicity, urbanization status, and geographical region (Ptrend < .05 for all). The AAMR (per 100,000 people) for ARF (91.3 [95% CI, 90.8-91.8]) and ARDS-related mortality (3.3 [95% CI, 3.2-3.4]) in 2018 were highest in the South.

INTERPRETATION

The ARF-related mortality increased at approximately 3.4% annually, and ARDS-related mortality showed a lack of decline in the last 5 years. These data contextualize important health information to guide priorities for research, clinical care, and policy, especially during the coronavirus disease 2019 pandemic in the United States.

Risk of Acute Respiratory Distress Syndrome Among Older Adults Living Near Construction and Manufacturing Sites

BACKGROUND

Construction and manufacturing sites produce airborne toxins that may affect nearby residents' respiratory health. Living in heavy industrial sites has been linked to respiratory conditions such as asthma and pneumonia. However, limited information is available for risk of acute respiratory distress syndrome (ARDS), a form of acute respiratory failure with high incidence among older adults.

METHODS

We conducted a nationwide ecologic study to investigate associations between annual ZIP code-level changes in industrial activity and annual changes in ZIP code-level hospital admission rates for older community residents. Using adjusted generalized linear mixed models, we analyzed data from nearly 30 million yearly Medicare beneficiaries for the years 2006 through 2012.

RESULTS

We found on average 92,363 hospital admissions for ARDS per year and 646,542 admissions over the course of 7 years. We found that an increase of 10 construction sites per year was associated with a 0.77% (95% confidence interval [CI] = 0.71, 0.84) increase in annual hospital admission rates for ARDS and an increase of 10 manufacturing industries per year was associated with a 1.21% (95% CI = 1.09, 1.33) increase in annual hospital admission rates for ARDS across all ZIP codes. The estimated effect of chemical product manufacturing industry on ARDS was higher than that of total manufacturing industries. Residing in ZIP codes with a high number of construction or manufacturing sites was associated with increased ARDS hospital admissions.

CONCLUSIONS

This nationwide ecologic study of older adults suggests that residence in areas with more construction and manufacturing sites is associated with increased ARDS risk.

Racial Disparities in Readmissions Following Initial Hospitalization for Sepsis

OBJECTIVES

To assess whether Black race is associated with a higher rate of all-cause readmission compared with White race following community-onset sepsis.

DESIGN

Retrospective cohort study.

SETTING

One-thousand three-hundred bed urban academic medical centers.

PATIENTS

Three-thousand three-hundred ninety patients hospitalized with community-onset sepsis between January 1, 2010, and December 31, 2017.

INTERVENTIONS

Community-onset sepsis was defined as patients admitted through the emergency department with an International Classification of Disease, ninth revision, Clinical Modification code for either severe sepsis (995.92) or septic shock (785.52). Beginning in 2015, we used International Classification of Disease, Tenth Revision, Clinical Modification codes R65.20 (severe sepsis) and R65.21 (septic shock). We excluded those individuals hospitalized at another acute care facility that were transferred to our facility. Race was abstracted electronically, and patients who expired or self-identified as a race other than Black or White race were excluded. Patients who experienced a subsequent hospitalization at our facility were considered to be readmitted.

MEASUREMENTS AND MAIN RESULTS

Compared with White race, Black race demonstrated a significantly higher rate of all-cause readmission (60.8% vs 71.1%; p < 0.001), including a higher rate of readmission for sepsis (14.0% vs 19.8%; p < 0.001). Black patients also resided in zip codes with a lower median household income and were more likely to use public insurance compared with White race. Similar rates of comorbid diseases and disease burden were observed between the two groups, but vasopressors were less likely to be administered to Black patients. Multivariable analysis showed that Black race was associated with a 50% increased odds (odds ratio, 1.52, 99% CI, 1.25-1.84) in all-cause readmission risk compared with White race.

CONCLUSIONS

Black race was associated with a higher rate of all-cause and sepsis readmission, possibly as a result of unaddressed health disparities, compared with White race. Programs addressing healthcare disparities should use readmission as another marker of equity.

Socioeconomic Factors and Intensive Care Unit-Related Cognitive Impairment

OBJECTIVE

We aimed to identify socioeconomic and clinical risk factors for post-intensive care unit (ICU)-related long-term cognitive impairment (LTCI).

SUMMARY BACKGROUND DATA

After delirium during ICU stay, LTCI has been increasingly recognized, but without attention to socioeconomic factors.

METHODS

We enrolled a prospective, multicenter cohort of ICU survivors with shock or respiratory failure from surgical and medical ICUs across 5 civilian and Veteran Affairs (VA) hospitals from 2010 to 2016. Our primary outcome was LTCI at 3- and 12 months post-hospital discharge defined by the Repeatable Battery for Assessment of Neuropsychological Symptoms (RBANS) global score. Covariates adjusted using multivariable linear regression included age, sex, race, AHRQ socioeconomic index, Charlson comorbidity, Framingham stroke risk, Sequential Organ Failure Assessment, duration of coma, delirium, hypoxemia, sepsis, education level, hospital type, insurance status, discharge disposition, and ICU drug exposures.

RESULTS

Of 1040 patients, 71% experienced delirium, and 47% and 41% of survivors had RBANS scores >1 standard deviation below normal at 3- and 12 months, respectively. Adjusted analysis indicated that delirium, non-White race, lower education, and civilian hospitals (as opposed to VA), were associated with at least a half standard deviation lower RBANS scores at 3- and 12 months (P ≤ 0.03). Sex, AHRQ socioeconomic index, insurance status, and discharge disposition were not associated with RBANS scores.

CONCLUSIONS

Socioeconomic and clinical risk factors, such as race, education, hospital type, and delirium duration, were linked to worse PICS ICU-related, LTCI. Further efforts may focus on improved identification of higher-risk groups to promote survivorship through emerging improvements in cognitive rehabilitation.

Ethnicity and risk of death in patients hospitalised for COVID-19 infection in the UK: an observational cohort study in an urban catchment area

BACKGROUND

Studies suggest that certain black and Asian minority ethnic groups experience poorer outcomes from COVID-19, but these studies have not provided insight into potential reasons for this. We hypothesised that outcomes would be poorer for those of South Asian ethnicity hospitalised from a confirmed SARS-CoV-2 infection, once confounding factors, health-seeking behaviours and community demographics were considered, and that this might reflect a more aggressive disease course in these patients.

METHODS

Patients with confirmed SARS-CoV-2 infection requiring admission to University Hospitals Birmingham NHS Foundation Trust (UHB) in Birmingham, UK between 10 March 2020 and 17 April 2020 were included. Standardised admission ratio (SAR) and standardised mortality ratio (SMR) were calculated using observed COVID-19 admissions/deaths and 2011 census data. Adjusted HR for mortality was estimated using Cox proportional hazard model adjusting and propensity score matching.

RESULTS

All patients admitted to UHB with COVID-19 during the study period were included (2217 in total). 58% were male, 69.5% were white and the majority (80.2%) had comorbidities. 18.5% were of South Asian ethnicity, and these patients were more likely to be younger and have no comorbidities, but twice the prevalence of diabetes than white patients. SAR and SMR suggested more admissions and deaths in South Asian patients than would be predicted and they were more likely to present with severe disease despite no delay in presentation since symptom onset. South Asian ethnicity was associated with an increased risk of death, both by Cox regression (HR 1.4, 95% CI 1.2 to 1.8), after adjusting for age, sex, deprivation and comorbidities, and by propensity score matching, matching for the same factors but categorising ethnicity into South Asian or not (HR 1.3, 95% CI 1.0 to 1.6).

CONCLUSIONS

Those of South Asian ethnicity appear at risk of worse COVID-19 outcomes. Further studies need to establish the underlying mechanistic pathways.

Systems Biology ARDS Research with a Focus on Metabolomics

Acute respiratory distress syndrome (ARDS) is a clinical syndrome that inflicts a considerably heavy toll in terms of morbidity and mortality. While there are multitudes of conditions that can lead to ARDS, the vast majority of ARDS cases are caused by a relatively small number of diseases, especially sepsis and pneumonia. Currently, there is no clinically agreed upon reliable diagnostic test for ARDS, and the detection or diagnosis of ARDS is based on a constellation of laboratory and radiological tests in the absence of evidence of left ventricular dysfunction, as specified by the Berlin definition of ARDS. Virtually all the ARDS biomarkers to date have been proven to be of very limited clinical utility. Given the heterogeneity of ARDS due to the wide variation in etiology, clinical and molecular manifestations, there is a current scientific consensus agreement that ARDS is not just a single entity but rather a spectrum of conditions that need further study for proper classification, the identification of reliable biomarkers and the adequate institution of therapeutic targets. This scoping review aims to elucidate ARDS omics research, focusing on metabolomics and how metabolomics can boost the study of ARDS biomarkers and help to facilitate the identification of ARDS subpopulations.

Validation of age, PaO2/FlO2 and plateau pressure score in Korean patients with acute respiratory distress syndrome: a retrospective cohort study

Background

A predictive scoring system for acute respiratory distress syndrome (ARDS) patients, which incorporates age, PaO₂/FlO₂, and plateau pressure, APPS, was developed recently. It was validated externally in a Caucasian population but has not been studied in Asian populations. The aim of this study was to validate APPS in Korean ARDS patients.

Methods

We retrospectively reviewed the medical records of patients who were diagnosed with ARDS using the Berlin criteria and admitted to the medical ICU at Seoul National University Hospital from January 2015 to December 2016. The validation of the APPS was performed by evaluating its calibration and predictive accuracy. Its calibration was plotted and quantified using the Hosmer–Lemeshow test. Its predictive accuracy was assessed by calculating the area under the receiver operating characteristics (AUC–ROC) curve.

Results

A total of 116 patients were analyzed, 32 of whom survived. Of the 116 patients, 11 (9.5%) were classified as APPS grade 1 (score 3–4), 88 (75.9%) as grade 2 (score 5–7) and 17 (14.6%) as grade 3 (score 8–9). In-hospital mortality was 27.3% for grade 1, 73.9% for grade 2 and 94.1% for grade 3 (P for trend < 0.001). The APPS was well calibrated (Hosmer–Lemeshow test, P = 0.578) and its predictive accuracy was acceptable (AUC–ROC 0.704, 95% confidence interval 0.599–0.809).

Conclusions

The APPS predicted in-hospital mortality in Korean patients with ARDS with similar power to its application in a Western population and with acceptable predictive accuracy.

Trial registration

Retrospectively registered.

The Flaw of Medicine: Addressing Racial and Gender Disparities in Critical Care

The age of modern medicine has ushered in remarkable advances and with them increased longevity of life. The questions are, however: Has everyone benefited from these developments equally? and Do all lives truly matter? The presence of gender and racial health disparities indicates that there is work still left to be done. The first target of intervention may well be the medical establishment itself. The literature presented in this article identifies potential targets for interventions and future areas of exploration.

Risk Factors and Etiologies of Pediatric Acute Respiratory Distress Syndrome

The risk factors for acute respiratory distress syndrome (ARDS) have been a focus for clinicians and researchers from the original description in 1967 to the most recent Pediatric Acute Lung Injury Consensus Conference (PALICC). Indeed, there are many comorbidities and risk factors that predispose a patient to develop pediatric ARDS (PARDS) including, but not limited to, immunodeficiency, weight extremes, genetics, and environmental factors. These are particularly important to investigators because accurate prediction of which patients are at greatest risk of PARDS – both the development of PARDS and worse clinical outcomes after PARDS has been established – is key to identifying the next generation of diagnostic techniques and preventative strategies. In addition to those risk factors, there are specific disease processes that lead to the development of PARDS, often divided into direct or pulmonary insults and indirect or extrapulmonary insults. Finally, beyond the clinically visible risk factors, researchers are attempting to identify novel biomarkers to uncover hidden phenotypes of PARDS and enrich the prognostication and prediction of patient outcomes. This chapter delves into each of these concepts.

Genomic and Genetic Approaches to Deciphering Acute Respiratory Distress Syndrome Risk and Mortality

Significance: Acute respiratory distress syndrome (ARDS) is a severe, highly heterogeneous critical illness with staggering mortality that is influenced by environmental factors, such as mechanical ventilation, and genetic factors. Significant unmet needs in ARDS are addressing the paucity of validated predictive biomarkers for ARDS risk and susceptibility that hamper the conduct of successful clinical trials in ARDS and the complete absence of novel disease-modifying therapeutic strategies. Recent Advances: The current ARDS definition relies on clinical characteristics that fail to capture the diversity of disease pathology, severity, and mortality risk. We undertook a comprehensive survey of the available ARDS literature to identify genes and genetic variants (candidate gene and limited genome-wide association study approaches) implicated in susceptibility to developing ARDS in hopes of uncovering novel biomarkers for ARDS risk and mortality and potentially novel therapeutic targets in ARDS. We further attempted to address the well-known health disparities that exist in susceptibility to and mortality from ARDS. Critical Issues: Bioinformatic analyses identified 201 ARDS candidate genes with pathway analysis indicating a strong predominance in key evolutionarily conserved inflammatory pathways, including reactive oxygen species, innate immunity-related inflammation, and endothelial vascular signaling pathways. Future Directions: Future studies employing a system biology approach that combines clinical characteristics, genomics, transcriptomics, and proteomics may allow for a better definition of biologically relevant pathways and genotype-phenotype connections and result in improved strategies for the sub-phenotyping of diverse ARDS patients via molecular signatures. These efforts should facilitate the potential for successful clinical trials in ARDS and yield a better fundamental understanding of ARDS pathobiology.

Clinical epidemiology and mortality on patients with acute respiratory distress syndrome (ARDS) in Vietnam

BACKGROUND

The clinical epidemiology and disease prognosis in patients with acute respiratory distress syndrome (ARDS) have not yet been fully elucidated in Vietnam.

METHODS

We conducted a retrospective observational study at a national tertiary hospital in Hanoi, Vietnam. Participants were adult patients (age ≥18 years) who were admitted and diagnosed with ARDS during 2015-2017. Data on patients' general and clinical conditions, radiographic findings, ventilator settings, gas exchange, and treatment methods were collected and compared between survivors and non-survivors. Risk factors for mortality were assessed using logistic regression analysis.

RESULTS

Among 126 eligible patients with ARDS admitted to the central tertiary hospital in Vietnam, we observed high mortality (57.1%). Of the total patients, 91.3% were transferred from local hospitals with a diagnosis of severe pneumonia and then diagnosed with ARDS at the central hospital. At the time of admission, 53.2% of patients had severe ARDS, 37.3% had moderate ARDS, and 9.5% had mild ARDS. The mean (standard deviation) sequential organ failure assessment (SOFA) score was 9.5 (3.4) in non-survivors and 7.4 (3.4) in survivors (p = 0.002). Although there was no significant difference in PaO2/FiO2 on admission between non-survivors and survivors, that on day 3 after admission was significantly different (p = 0.002). Logistic regression revealed that PaO2/FiO2 on day 3 [odds ratio (OR), 1.010; 95% confidence interval (CI), 1.003-1.017], length of stay in a local hospital before admission to the central hospital (OR, 1.122; 95% CI, 1.042-1.210) due to stable condition, and SOFA score on Day 1 (OR, 0.842; 95% CI, 0.708-1.002) were independent factors in patient survival.

CONCLUSIONS

Patients with ARDS admitted the central tertiary hospital had severe illness and high mortality. Most patients were transferred from local hospitals. Improvements in human, medical, and sociological resources in local will contribute to reducing the mortality of ARDS in Vietnam.

Pulmonary Endothelial Mechanical Sensing and Signaling, a Story of Focal Adhesions and Integrins in Ventilator Induced Lung Injury

Patients with critical illness such as acute lung injury often undergo mechanical ventilation in the intensive care unit. Though lifesaving in many instances, mechanical ventilation often results in ventilator induced lung injury (VILI), characterized by overdistension of lung tissue leading to release of edemagenic agents, which further damage the lung and contribute to the mortality and progression of pulmonary inflammation. The endothelium is particularly sensitive, as VILI associated mechanical stress results in endothelial cytoskeletal rearrangement, stress fiber formation, and integrity loss. At the heart of these changes are integrin tethered focal adhesions (FAs) which participate in mechanosensing, structure, and signaling. Here, we present the known roles of FA proteins including c-Src, talin, FAK, paxillin, vinculin, and integrins in the sensing and response to cyclic stretch and VILI associated stress. Attention is given to how stretch is propagated from the extracellular matrix through integrins to talin and other FA proteins, as well as signaling cascades that include FA proteins, leading to stress fiber formation and other cellular responses. This unifying picture of FAs aids our understanding in an effort to prevent and treat VILI.

Acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in critically ill patients and is defined by the acute onset of noncardiogenic pulmonary oedema, hypoxaemia and the need for mechanical ventilation. ARDS occurs most often in the setting of pneumonia, sepsis, aspiration of gastric contents or severe trauma and is present in ~10% of all patients in intensive care units worldwide. Despite some improvements, mortality remains high at 30-40% in most studies. Pathological specimens from patients with ARDS frequently reveal diffuse alveolar damage, and laboratory studies have demonstrated both alveolar epithelial and lung endothelial injury, resulting in accumulation of protein-rich inflammatory oedematous fluid in the alveolar space. Diagnosis is based on consensus syndromic criteria, with modifications for under-resourced settings and in paediatric patients. Treatment focuses on lung-protective ventilation; no specific pharmacotherapies have been identified. Long-term outcomes of patients with ARDS are increasingly recognized as important research targets, as many patients survive ARDS only to have ongoing functional and/or psychological sequelae. Future directions include efforts to facilitate earlier recognition of ARDS, identifying responsive subsets of patients and ongoing efforts to understand fundamental mechanisms of lung injury to design specific treatments.

Paediatric acute respiratory distress syndrome incidence and epidemiology (PARDIE): an international, observational study

BACKGROUND

Paediatric acute respiratory distress syndrome (PARDS) is associated with high mortality in children, but until recently no paediatric-specific diagnostic criteria existed. The Pediatric Acute Lung Injury Consensus Conference (PALICC) definition was developed to overcome limitations of the Berlin definition, which was designed and validated for adults. We aimed to determine the incidence and outcomes of children who meet the PALICC definition of PARDS.

METHODS

In this international, prospective, cross-sectional, observational study, 145 paediatric intensive care units (PICUs) from 27 countries were recruited, and over a continuous 5 day period across 10 weeks all patients were screened for enrolment. Patients were included if they had a new diagnosis of PARDS that met PALICC criteria during the study week. Exclusion criteria included meeting PARDS criteria more than 24 h before screening, cyanotic heart disease, active perinatal lung disease, and preparation or recovery from a cardiac intervention. Data were collected on the PICU characteristics, patient demographics, and elements of PARDS (ie, PARDS risk factors, hypoxaemia severity metrics, type of ventilation), comorbidities, chest imaging, arterial blood gas measurements, and pulse oximetry. The primary outcome was PICU mortality. Secondary outcomes included 90 day mortality, duration of invasive mechanical and non-invasive ventilation, and cause of death.

FINDINGS

Between May 9, 2016, and June 16, 2017, during the 10 study weeks, 23 280 patients were admitted to participating PICUs, of whom 744 (3·2%) were identified as having PARDS. 95% (708 of 744) of patients had complete data for analysis, with 17% (121 of 708; 95% CI 14-20) mortality, whereas only 32% (230 of 708) of patients met Berlin criteria with 27% (61 of 230) mortality. Based on hypoxaemia severity at PARDS diagnosis, mortality was similar among those who were non-invasively ventilated and with mild or moderate PARDS (10-15%), but higher for those with severe PARDS (33% [54 of 165; 95% CI 26-41]). 50% (80 of 160) of non-invasively ventilated patients with PARDS were subsequently intubated, with 25% (20 of 80; 95% CI 16-36) mortality. By use of PALICC PARDS definition, severity of PARDS at 6 h after initial diagnosis (area under the curve [AUC] 0·69, 95% CI 0·62-0·76) discriminates PICU mortality better than severity at PARDS diagnosis (AUC 0·64, 0·58-0·71), and outperforms Berlin severity groups at 6 h (0·64, 0·58-0·70; p=0·01).

INTERPRETATION

The PALICC definition identified more children as having PARDS than the Berlin definition, and PALICC PARDS severity groupings improved the stratification of mortality risk, particularly when applied 6 h after PARDS diagnosis. The PALICC PARDS framework should be considered for use in future epidemiological and therapeutic research among children with PARDS.

FUNDING

University of Southern California Clinical Translational Science Institute, Sainte Justine Children's Hospital, University of Montreal, Canada, Réseau en Santé Respiratoire du Fonds de Recherche Quebec-Santé, and Children's Hospital Los Angeles, Department of Anesthesiology and Critical Care Medicine.

Disease prevention & health promotion: what's critical care got to do with it?

Health systems are increasingly investing in efforts to prevent disease and promote health for populations. By and large, these prevention-related interventions have not been inclusive of critical care and the intensive care unit (ICU). However, we suggest that there is value-to patients, families, health systems, and society at large-in extending this continuum into the ICU setting and including the ICU in disease prevention and health promotion efforts. Including the ICU in this continuum allows the critical care perspective to inform (I) advocacy for prevention; (II) efforts to improve disparities in health and health care; (III) mitigation of the negative effects of critical illness and injury as well as ICU exposure; and (IV) promotion of health and well-being in the community. As disease prevention and health promotion rise as priorities within health systems, critical care can and should join, even help lead, the effort.

A vascular endothelial growth factor receptor gene variant is associated with susceptibility to acute respiratory distress syndrome

BACKGROUND

The acute respiratory distress syndrome (ARDS) is one of the main causes of mortality in adults admitted to intensive care units. Previous studies have demonstrated the existence of genetic variants involved in the susceptibility and outcomes of this syndrome. We aimed to identify novel genes implicated in sepsis-induced ARDS susceptibility.

METHODS

We first performed a prioritization of candidate genes by integrating our own genomic data from a transcriptomic study in an animal model of ARDS and from the only published genome-wide association study of ARDS study in humans. Then, we selected single nucleotide polymorphisms (SNPs) from prioritized genes to conduct a case-control discovery association study in patients with sepsis-induced ARDS (n = 225) and population-based controls (n = 899). Finally, we validated our findings in an independent sample of 661 sepsis-induced ARDS cases and 234 at-risk controls.

RESULTS

Three candidate genes were prioritized: dynein cytoplasmic-2 heavy chain-1, fms-related tyrosine kinase 1 (FLT1), and integrin alpha-1. Of those, a SNP from FLT1 gene (rs9513106) was associated with ARDS in the discovery study, with an odds ratio (OR) for the C allele of 0.76, 95% confidence interval (CI) 0.58-0.98 (p = 0.037). This result was replicated in an independent study (OR = 0.78, 95% CI = 0.62-0.98, p = 0.039), showing consistent direction of effects in a meta-analysis (OR = 0.77, 95% CI = 0.65-0.92, p = 0.003).

CONCLUSIONS

We identified FLT1 as a novel ARDS susceptibility gene and demonstrated that integration of genomic data can be a valid procedure to identify novel susceptibility genes. These results contribute to previous firm associations and functional evidences implicating FLT1 gene in other complex traits that are mechanistically linked, through the key role of endothelium, to the pathophysiology of ARDS.