Demographics, management and outcome of females and males with acute respiratory distress syndrome in the LUNG SAFE prospective cohort study

Phenotyping COVID-19 respiratory failure in spontaneously breathing patients with AI on lung CT-scan

BACKGROUND

Automated analysis of lung computed tomography (CT) scans may help characterize subphenotypes of acute respiratory illness. We integrated lung CT features measured via deep learning with clinical and laboratory data in spontaneously breathing subjects to enhance the identification of COVID-19 subphenotypes.

METHODS

This is a multicenter observational cohort study in spontaneously breathing patients with COVID-19 respiratory failure exposed to early lung CT within 7 days of admission. We explored lung CT images using deep learning approaches to quantitative and qualitative analyses; latent class analysis (LCA) by using clinical, laboratory and lung CT variables; regional differences between subphenotypes following 3D spatial trajectories.

RESULTS

Complete datasets were available in 559 patients. LCA identified two subphenotypes (subphenotype 1 and 2). As compared with subphenotype 2 (n = 403), subphenotype 1 patients (n = 156) were older, had higher inflammatory biomarkers, and were more hypoxemic. Lungs in subphenotype 1 had a higher density gravitational gradient with a greater proportion of consolidated lungs as compared with subphenotype 2. In contrast, subphenotype 2 had a higher density submantellar-hilar gradient with a greater proportion of ground glass opacities as compared with subphenotype 1. Subphenotype 1 showed higher prevalence of comorbidities associated with endothelial dysfunction and higher 90-day mortality than subphenotype 2, even after adjustment for clinically meaningful variables.

CONCLUSIONS

Integrating lung-CT data in a LCA allowed us to identify two subphenotypes of COVID-19, with different clinical trajectories. These exploratory findings suggest a role of automated imaging characterization guided by machine learning in subphenotyping patients with respiratory failure.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04395482. Registration date: 19/05/2020.

Mortality Due to Acute Respiratory Distress Syndrome in Latin America

OBJECTIVES

Mortality due to acute respiratory distress syndrome (ARDS) is a major global health problem. Knowledge of epidemiological data on ARDS is crucial to design management, treatment strategies, and optimize resources. There is ample data regarding mortality of ARDS from high-income countries; in this review, we evaluated mortality due to ARDS in Latin America.

DATA SOURCES

We searched in PubMed, Cochrane Central Register of Controlled Trials, Web of Science, and Latin American and Caribbean Health Science Literature databases from 1967 to March 2023.

STUDY SELECTION

We searched prospective or retrospective observational studies and randomized controlled trials conducted in Latin American countries reporting ARDS mortality.

DATA EXTRACTION

Three pairs of independent reviewers checked all studies for eligibility based on their titles and abstracts. We performed meta-analysis of proportions using a random-effects model. We performed sensitivity analyses including studies with low risk of bias and with diagnosis using the Berlin definition. Subgroup analysis comparing different study designs, time of publication (up to 2000 and from 2001 to present), and studies in which the diagnosis of ARDS was made using Pa o2 /F io2 less than or equal to 200 and regional variations. Subsequently, we performed meta-regression analyses. Finally, we graded the certainty of the evidence (Grading of Recommendations Assessment, Development, and Evaluation).

DATA SYNTHESIS

Of 3315 articles identified, 32 were included (3627 patients). Mortality was 52% in the pooled group (low certainty of evidence). In the sensitivity analysis (according to the Berlin definition), mortality was 46% (moderate certainty of evidence). In the subgroup analysis mortality was 53% (randomized controlled trials), 51% (observational studies), 66% (studies published up to 2000), 50% (studies after 2000), 44% (studies with Pa o2 /F io2 ≤ 200), 56% (studies from Argentina/Brazil), and 40% (others countries). No variables were associated with mortality in the meta-regression.

CONCLUSIONS

ARDS mortality in Latin America remains high, as in other regions. These results should constitute the basis for action planning to improve the prognosis of patients with ARDS (PROSPERO [CRD42022354035]).

Algor-ethics: charting the ethical path for AI in critical care

The integration of Clinical Decision Support Systems (CDSS) based on artificial intelligence (AI) in healthcare is groundbreaking evolution with enormous potential, but its development and ethical implementation, presents unique challenges, particularly in critical care, where physicians often deal with life-threating conditions requiring rapid actions and patients unable to participate in the decisional process. Moreover, development of AI-based CDSS is complex and should address different sources of bias, including data acquisition, health disparities, domain shifts during clinical use, and cognitive biases in decision-making. In this scenario algor-ethics is mandatory and emphasizes the integration of 'Human-in-the-Loop' and 'Algorithmic Stewardship' principles, and the benefits of advanced data engineering. The establishment of Clinical AI Departments (CAID) is necessary to lead AI innovation in healthcare, ensuring ethical integrity and human-centered development in this rapidly evolving field.

Sex differences in the use of mechanical ventilation in a neurointensive care population: a retrospective study

BACKGROUND

In the general intensive care unit (ICU) women receive invasive mechanical ventilation (IMV) less frequently than men. We investigated whether sex differences in the use of IMV also exist in the neurocritical care unit (NCCU), where patients are intubated not only due to respiratory failure but also due to neurological impairment.

METHODS

This retrospective single-centre study included adults admitted to the NCCU of the University Hospital Zurich between January 2018 and August 2021 with neurological or neurosurgical main diagnosis. We collected data on demographics, intubation, re-intubation, tracheotomy, and duration of IMV or other forms of respiratory support from the Swiss ICU registry or the medical records. A descriptive statistics was performed. Baseline and outcome characteristics were compared by sex in the whole population and in subgroup analysis.

RESULTS

Overall, 963 patients were included. No differences between sexes in the use and duration of IMV, frequency of emergency or planned intubations, tracheostomy were found. The duration of oxygen support was longer in women (men 2 [2, 4] vs. women 3 [1, 6] days, p = 0.018), who were more often admitted due to subarachnoid hemorrhage (SAH). No difference could be found after correction for age, diagnosis of admission and severity of disease.

CONCLUSION

In this NCCU population and differently from the general ICU population, we found no difference by sex in the frequency and duration of IMV, intubation, reintubation, tracheotomy and non-invasive ventilation support. These results suggest that the differences in provision of care by sex reported in the general ICU population may be diagnosis-dependent. The difference in duration of oxygen supplementation observed in our population can be explained by the higher prevalence of SAH in women, where we aim for higher oxygenation targets due to the specific risk of vasospasm.

Sex differences in treatments and outcomes of patients with cardiogenic shock: a systematic review and epidemiological meta-analysis

BACKGROUND

Women are at higher risk of mortality from many acute cardiovascular conditions, but studies have demonstrated differing findings regarding the mortality of cardiogenic shock in women and men. To examine differences in 30-day mortality and mechanical circulatory support use by sex in patients with cardiogenic shock.

MAIN BODY

Cochrane Central, PubMed, MEDLINE and EMBASE were searched in April 2024. Studies were included if they were randomised controlled trials or observational studies, included adult patients with cardiogenic shock, and reported at least one of the following outcomes by sex: raw mortality, adjusted mortality (odds ratio) or use of mechanical circulatory support. Out of 4448 studies identified, 81 met inclusion criteria, pooling a total of 656,754 women and 1,018,036 men. In the unadjusted analysis for female sex and combined in-hospital and 30-day mortality, women had higher odds of mortality (Odds Ratio (OR) 1.35, 95% confidence interval (CI) 1.26-1.44, p < 0.001). Pooled unadjusted mortality was 35.9% in men and 40.8% in women (p < 0.001). When only studies reporting adjusted ORs were included, combined in-hospital/30-day mortality remained higher in women (OR 1.10, 95% CI 1.06-1.15, p < 0.001). These effects remained consistent across subgroups of acute myocardial infarction- and heart failure- related cardiogenic shock. Overall, women were less likely to receive mechanical support than men (OR = 0.67, 95% CI 0.57-0.79, p < 0.001); specifically, they were less likely to be treated with intra-aortic balloon pump (OR = 0.79, 95% CI 0.71-0.89, p < 0.001) or extracorporeal membrane oxygenation (OR = 0.84, 95% 0.71-0.99, p = 0.045). No significant difference was seen with use of percutaneous ventricular assist devices (OR = 0.82, 95% CI 0.51-1.33, p = 0.42).

CONCLUSION

Even when adjusted for confounders, mortality for cardiogenic shock in women is approximately 10% higher than men. This effect is seen in both acute myocardial infarction and heart failure cardiogenic shock. Women with cardiogenic shock are less likely to be treated with mechanical circulatory support than men. Clinicians should make immediate efforts to ensure the prompt diagnosis and aggressive treatment of cardiogenic shock in women.

A preclinical systematic review and meta-analysis assessing the effect of biological sex in lipopolysaccharide-induced acute lung injury

It is unclear what effect biological sex has on outcomes of acute lung injury (ALI). Clinical studies are confounded by their observational design. We addressed this knowledge gap with a preclinical systematic review of ALI animal studies. We searched MEDLINE and Embase for studies of intratracheal/intranasal/aerosolized lipopolysaccharide administration (the most common ALI model) that reported sex-stratified data. Screening and data extraction were conducted in duplicate. Our primary outcome was histological tissue injury and secondary outcomes included alveolar-capillary barrier alterations and inflammatory markers. We used a random-effects inverse variance meta-analysis, expressing data as standardized mean difference (SMD) with 95% confidence intervals (CIs). Risk of bias was assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool. We identified six studies involving 132 animals across 11 independent experiments. A total of 41 outcomes were extracted, with the direction of effect suggesting greater severity in males than females in 26/41 outcomes (63%). One study reported on lung histology and found that male mice exhibited greater injury than females (SMD: 1.61, 95% CI: 0.53-2.69). Meta-analysis demonstrated significantly elevated albumin levels (SMD: 2.17, 95% CI: 0.63-3.70) and total cell counts (SMD: 0.80, 95% CI: 0.27-1.33) in bronchoalveolar lavage fluid from male mice compared with female mice. Most studies had an "unclear risk of bias." Our findings suggest sex-related differences in ALI severity. However, these conclusions are drawn from a small number of animals and studies. Further research is required to address the fundamental issue of biological sex differences in LPS-induced ALI.

A BAYESIAN MACHINE LEARNING APPROACH FOR ESTIMATING HETEROGENEOUS SURVIVOR CAUSAL EFFECTS: APPLICATIONS TO A CRITICAL CARE TRIAL

Assessing heterogeneity in the effects of treatments has become increasingly popular in the field of causal inference and carries important implications for clinical decision-making. While extensive literature exists for studying treatment effect heterogeneity when outcomes are fully observed, there has been limited development in tools for estimating heterogeneous causal effects when patient-centered outcomes are truncated by a terminal event, such as death. Due to mortality occurring during study follow-up, the outcomes of interest are unobservable, undefined, or not fully observed for many participants in which case principal stratification is an appealing framework to draw valid causal conclusions. Motivated by the Acute Respiratory Distress Syndrome Network (ARDSNetwork) ARDS respiratory management (ARMA) trial, we developed a flexible Bayesian machine learning approach to estimate the average causal effect and heterogeneous causal effects among the always-survivors stratum when clinical outcomes are subject to truncation. We adopted Bayesian additive regression trees (BART) to flexibly specify separate mean models for the potential outcomes and latent stratum membership. In the analysis of the ARMA trial, we found that the low tidal volume treatment had an overall benefit for participants sustaining acute lung injuries on the outcome of time to returning home but substantial heterogeneity in treatment effects among the always-survivors, driven most strongly by biologic sex and the alveolar-arterial oxygen gradient at baseline (a physiologic measure of lung function and degree of hypoxemia). These findings illustrate how the proposed methodology could guide the prognostic enrichment of future trials in the field.

The Appropriateness of Medical Devices Is Strongly Influenced by Sex and Gender

Until now, research has been performed mainly in men, with a low recruitment of women; consequentially, biological, physiological, and physio-pathological mechanisms are less understood in women. Obviously, without data obtained on women, it is impossible to apply the results of research appropriately to women. This issue also applies to medical devices (MDs), and numerous problems linked to scarce pre-market research and clinical trials on MDs were evidenced after their introduction to the market. Globally, some MDs are less efficient in women than in men and sometimes MDs are less safe for women than men, although recently there has been a small but significant decrease in the sex and gender gap. As an example, cardiac resynchronization defibrillators seem to produce more beneficial effects in women than in men. It is also important to remember that MDs can impact the health of healthcare providers and this could occur in a sex- and gender-dependent manner. Recently, MDs' complexity is rising, and to ensure their appropriate use they must have a sex-gender-sensitive approach. Unfortunately, the majority of physicians, healthcare providers, and developers of MDs still believe that the human population is only constituted by men. Therefore, to overcome the gender gap, a real collaboration between the inventors of MDs, health researchers, and health providers should be established to test MDs in female and male tissues, animals, and women.

Low Tidal Volume Ventilation Is Poorly Implemented for Patients in North American and United Kingdom ICUs Using Electronic Health Records

BACKGROUND

Low tidal volume ventilation (LTVV; < 8 mL/kg predicted body weight [PBW]) is a well-established standard of care associated with improved outcomes. This study used data collated in multicenter electronic health record ICU databases from the United Kingdom and the United States to analyze the use of LTVV in routine clinical practice.

RESEARCH QUESTION

What factors are associated with adherence to LTVV in the United Kingdom and North America?

STUDY DESIGN

This was a retrospective, multicenter study across the United Kingdom and United States of patients who were mechanically ventilated.

METHODS

Factors associated with adherence to LTVV were assessed in all patients in both databases who were mechanically ventilated for > 48 h. We observed trends over time and investigated whether LTVV was associated with patient outcomes (30-day mortality and duration of ventilation) and identified strategies to improve adherence to LTVV.

RESULTS

A total of 5,466 (Critical Care Health Informatics Collaborative [CCHIC]) and 7,384 electronic ICU collaborative research database [eICU-CRD] patients were ventilated for > 48 h and had data of suitable quality for analysis. The median tidal volume (VT) values were 7.48 mL/kg PBW (CCHIC) and 7.91 mL/kg PBW (eICU-CRD). The patients at highest risk of not receiving LTVV were shorter than 160 cm (CCHIC) and 165 cm (eICU-CRD). Those with BMI > 30 kg/m2 (CCHIC OR, 1.9 [95% CI, 1.7-2.13]; eICU-CRD OR, 1.61 [95% CI, 1.49-1.75]) and female patients (CCHIC OR, 2.39 [95% CI, 2.16-2.65]; eICU-CRD OR, 2.29 [95% CI, 2.26-2.31]) were at increased risk of having median VT > 8 mL/kg PBW. Patients with median VT < 8 mL/kg PBW had decreased 30-day mortality in the CCHIC database (CCHIC cause-specific hazard ratio, 0.86 [95% CI, 0.76-0.97]; eICU-CRD cause-specific hazard ratio, 0.9 [95% CI, 0.86-1.00]). There was a significant reduction in VT over time in the CCHIC database.

INTERPRETATION

There has been limited implementation of LTVV in routine clinical practice in the United Kingdom and the United States. VT > 8 mL/kg PBW was associated with worse patient outcomes.

Translational medicine for acute lung injury

Acute lung injury (ALI) is a complex disease with numerous causes. This review begins with a discussion of disease development from direct or indirect pulmonary insults, as well as varied pathogenesis. The heterogeneous nature of ALI is then elaborated upon, including its epidemiology, clinical manifestations, potential biomarkers, and genetic contributions. Although no medication is currently approved for this devastating illness, supportive care and pharmacological intervention for ALI treatment are summarized, followed by an assessment of the pathophysiological gap between human ALI and animal models. Lastly, current research progress on advanced nanomedicines for ALI therapeutics in preclinical and clinical settings is reviewed, demonstrating new opportunities towards developing an effective treatment for ALI.

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.

Sex and gender differences in intensive care medicine

Despite significant advancements in critical care medicine, limited attention has been given to sex and gender disparities in management and outcomes of patients admitted to the intensive care unit (ICU). While "sex" pertains to biological and physiological characteristics, such as reproductive organs, chromosomes and sex hormones, "gender" refers more to sociocultural roles and human behavior. Unfortunately, data on gender-related topics in the ICU are lacking. Consequently, data on sex and gender-related differences in admission to the ICU, clinical course, length of stay, mortality, and post-ICU burdens, are often inconsistent. Moreover, when examining specific diagnoses in the ICU, variations can be observed in epidemiology, pathophysiology, presentation, severity, and treatment response due to the distinct impact of sex hormones on the immune and cardiovascular systems. In this narrative review, we highlight the influence of sex and gender on the clinical course, management, and outcomes of the most encountered intensive care conditions, in addition to the potential co-existence of unconscious biases which may also impact critical illness. Diagnoses with a known sex predilection will be discussed within the context of underlying sex differences in physiology, anatomy, and pharmacology with the goal of identifying areas where clinical improvement is needed. To optimize patient care and outcomes, it is crucial to comprehend and address sex and gender differences in the ICU setting and personalize management accordingly to ensure equitable, patient-centered care. Future research should focus on elucidating the underlying mechanisms driving sex and gender disparities, as well as exploring targeted interventions to mitigate these disparities and improve outcomes for all critically ill patients.

Decreased Utilization of Low Tidal Volume Ventilation Outside of the Intensive Care Unit as Compared to Inside

Background: Investigations into the use of low tidal volume ventilation (LTVV) have been performed for patients in emergency departments (EDs) or intensive care units (ICUs). Practice differences between the ICU and non-ICU care areas have not been described. We hypothesized that the initial implementation of LTVV would be better inside ICUs than outside. Methods: This is a retrospective observational study of patients initiated on invasive mechanical ventilation (IMV) between January 1, 2016, and July 17, 2019. Initial recorded tidal volumes after intubation were used to compare the use of LTVV between care areas. Low tidal volume was considered 6.5 cc/kg of ideal body weight (IBW) or less. The primary outcome was the initiation of low tidal volume. Sensitivity analyses used a tidal volume of 8 cc/kg of IBW or less, and direct comparisons were performed between the ICU, ED, and wards. Results: There were 6392 initiations of IMV: 2217 (34.7%) in the ICU and 4175 (65.3%) outside. LTVV was more likely to be initiated in the ICU than outside (46.5% vs 34.2%; adjusted odds ratio [aOR] 0.62, 95% confidence interval [CI] 0.56-0.71, P < .01). The ICU also had more implementation when PaO2/FiO2 ratio was less than 300, (48.0% vs 34.6%; aOR 0.59, 95% CI 0.48-0.71, P < .01). When comparing individual locations, wards had lower odds of LTVV than the ICU (aOR 0.82, 95% CI 0.70-0.96, P  =  .02), the ED had lower odds than the ICU (aOR 0.55, 95% CI 0.48-0.63, P < .01), and the ED had lower odds than the wards (aOR 0.66, 95% CI 0.56-0.77, P < .01). Interpretation: Initial low tidal volumes were more likely to be initiated in the ICU than outside. This finding remained when examining only patients with a PaO2/FiO2 ratio less than 300. Care areas outside of the ICU do not employ LTVV as often as ICUs and are, therefore, a possible target for process improvement.

Disparities in Adult Patient Selection for Extracorporeal Membrane Oxygenation in the United States: A Population-Level Study

Rationale: Disparities in patient selection for advanced therapeutics in health care have been identified in multiple studies, but it is unclear if disparities exist in patient selection for extracorporeal membrane oxygenation (ECMO), a rapidly expanding critical care resource. Objectives: To determine if disparities exist in patient selection for ECMO based on sex, primary insurance, and median income of the patient's neighborhood. Methods: In a retrospective cohort study using the Nationwide Readmissions Database 2016-2019, we identified patients treated with mechanical ventilation (MV) and/or ECMO with billing codes. Patient sex, insurance, and income level for patients receiving ECMO were compared with the patients treated with MV only, and hierarchical logistic regression with the hospital as a random intercept was used to determine odds of receiving ECMO based on patient demographics. Results: We identified 2,170,752 MV hospitalizations with 18,725 cases of ECMO. Among patients treated with ECMO, 36.1% were female compared with 44.5% of patients treated with> MV only (adjusted odds ratio [aOR] for ECMO, 0.73; 95% confidence interval [CI], 0.70-0.75). Of patients treated with ECMO, 38.1% had private insurance compared with 17.4% of patients treated with MV only. Patients with Medicaid were less likely to receive ECMO than patients with private insurance (aOR, 0.55; 95% CI, 0.52-0.57). Patients treated with ECMO were more likely to live in the highest-income neighborhoods compared with patients treated with MV only (25.1% vs. 17.3%). Patients living in the lowest-income neighborhoods were less likely to receive ECMO than those living in the highest-income neighborhoods (aOR, 0.63; 95% CI, 0.60-0.67). Conclusions: Significant disparities exist in patient selection for ECMO. Female patients, patients with Medicaid, and patients living in the lowest-income neighborhoods are less likely to be treated with ECMO. Despite possible unmeasured confounding, these findings were robust to multiple sensitivity analyses. On the basis of previous work describing disparities in other areas of health care, we speculate that limited access in some neighborhoods, restrictive/biased interhospital transfer practices, differences in patient preferences, and implicit provider bias may contribute to the observed differences. Future studies with more granular data are needed to identify and modify drivers of observed disparities.

Inhaled Nitric Oxide in Acute Respiratory Distress Syndrome Subsets: Rationale and Clinical Applications

Acute respiratory distress syndrome (ARDS) is a life-threatening condition, characterized by diffuse inflammatory lung injury. Since the coronavirus disease 2019 (COVID-19) pandemic spread worldwide, the most common cause of ARDS has been the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Both the COVID-19-associated ARDS and the ARDS related to other causes-also defined as classical ARDS-are burdened by high mortality and morbidity. For these reasons, effective therapeutic interventions are urgently needed. Among them, inhaled nitric oxide (iNO) has been studied in patients with ARDS since 1993 and it is currently under investigation. In this review, we aim at describing the biological and pharmacological rationale of iNO treatment in ARDS by elucidating similarities and differences between classical and COVID-19 ARDS. Thereafter, we present the available evidence on the use of iNO in clinical practice in both types of respiratory failure. Overall, iNO seems a promising agent as it could improve the ventilation/perfusion mismatch, gas exchange impairment, and right ventricular failure, which are reported in ARDS. In addition, iNO may act as a viricidal agent and prevent lung hyperinflammation and thrombosis of the pulmonary vasculature in the specific setting of COVID-19 ARDS. However, the current evidence on the effects of iNO on outcomes is limited and clinical studies are yet to demonstrate any survival benefit by administering iNO in ARDS.

Effect of low-to-moderate hyperoxia on lung injury in preclinical animal models: a systematic review and meta-analysis

BACKGROUND

Extensive animal investigation informed clinical practice regarding the harmful effects of high fractional inspired oxygen concentrations (FiO₂s > 0.60). Since questions persist whether lower but still supraphysiologic FiO₂ ≤ 0.60 and > 0.21 (FiO₂ ≤ 0.60/ > 0.21) are also harmful with inflammatory lung injury in patients, we performed a systematic review examining this question in animal models.

METHODS

Studies retrieved from systematic literature searches of three databases, that compared the effects of exposure to FiO₂ ≤ 0.60/ > 0.21 vs. FiO₂ = 0.21 for ≥ 24 h in adult in vivo animal models including an inflammatory challenge or not were analyzed. Survival, body weight and/or lung injury measures were included in meta-analysis if reported in ≥ 3 studies.

RESULTS

More than 600 retrieved reports investigated only FiO₂s > 0.60 and were not analyzed. Ten studies with an inflammatory challenge (6 infectious and 4 noninfectious) and 14 studies without, investigated FiO₂s ≤ 0.60/ > 0.21 and were analyzed separately. In seven studies with an inflammatory challenge, compared to FiO₂ = 0.21, FiO₂ ≤ 0.60/ > 0.21 had consistent effects across animal types on the overall odds ratio of survival (95%CI) that was on the side of harm but not significant [0.68 (0.38,1.23), p = 0.21; I² = 0%, p = 0.57]. However, oxygen exposure times were only 1d in 4 studies and 2-4d in another. In a trend approaching significance, FiO₂ ≤ 0.60/ > 0.21 with an inflammatory challenge consistently increased the standardized mean difference (95%CI) (SMD) in lung weights [0.47 (- 0.07,1.00), p = 0.09; I² = 0%, p = 0.50; n = 4 studies] but had inconsistent effects on lung lavage protein concentrations (n = 3), lung pathology scores (n = 4) and/or arterial oxygenation (n = 4) (I² ≥ 43%, p ≤ 0.17). Studies without an inflammatory challenge had consistent effects on lung lavage protein concentration (n = 3) SMDs on the side of being increased that was not significant [0.43 (- 0.23,1.09), p = 0.20; I² = 0%, p = 0.40] but had inconsistent effects on body and lung weights (n = 6 and 8 studies, respectively) (I² ≥ 71%, p < 0.01). Quality of evidence for studies was weak.

INTERPRETATION

Limited animal studies have investigated FiO₂ ≤ 0.60/ > 0.21 with clinically relevant models and endpoints but suggest even these lower FiO₂s may be injurious. Given the influence animal studies examining FiO₂ > 0.60 have had on clinical practice, additional ones investigating FiO₂ ≤ 0.60/ > 0.21 appear warranted, particularly in pneumonia models.

Construção e validação do instrumento de verificação da adesão às diretrizes brasileiras de ventilação mecânica

Objetivo: construir e validar um instrumento para verificar a adesão às recomendações das Diretrizes Brasileiras de Ventilação Mecânica dos profissionais de saúde envolvidos na assistência aos pacientes em Ventilação Mecânica Invasiva. Método: estudo metodológico conduzido entre setembro e dezembro de 2019, em um hospital público com 87 pacientes. Adotou-se o Índice de Validação de Conteúdo para a validação de conteúdo, o Coeficiente de Correlação de Pearson para a validade de critério, o alfa de Cronbach para a consistência interna, o Coeficiente Kappa e o Coeficiente de Correlação Intraclasse para a confiabilidade interobservador. Resultados: o instrumento apresentou validade de conteúdo e consistência interna aceitável. A correlação de Pearson, indicou uma correlação do escore de adesão com a saturação (r=0,31; p≤0,005), o escore médio para o observador A e B resultou, respectivamente, em 88,89(±5,23) e 88,86(±5,34) e o intervalo de confiança foi de 0,96. Conclusão: o instrumento se mostrou válido e confiável para verificar a adesão às Diretrizes Brasileiras de Ventilação Mecânica dos profissionais.

Unusual X chromosome inactivation maintenance in female alveolar type 2 cells is correlated with increased numbers of X-linked escape genes and sex-biased gene expression

Sex differences exist for many lung pathologies, including COVID-19 and pulmonary fibrosis, but the mechanistic basis for this remains unclear. Alveolar type 2 cells (AT2s), which play a key role in alveolar lung regeneration, express the X-linked Ace2 gene that has roles in lung repair and SARS-CoV-2 pathogenesis, suggesting that X chromosome inactivation (XCI) in AT2s might impact sex-biased lung pathology. Here we investigate XCI maintenance and sex-specific gene expression profiles using male and female AT2s. Remarkably, the inactive X chromosome (Xi) lacks robust canonical Xist RNA "clouds" and less enrichment of heterochromatic modifications in human and mouse AT2s. We demonstrate that about 68% of expressed X-linked genes in mouse AT2s, including Ace2, escape XCI. There are genome-wide expression differences between male and female AT2s, likely influencing both lung physiology and pathophysiologic responses. These studies support a renewed focus on AT2s as a potential contributor to sex-biased differences in lung disease.

Sex and Gender in Lung Diseases and Sleep Disorders: A State-of-the-Art Review: Part 2

There is now ample evidence that differences in sex and gender contribute to the incidence, susceptibility, presentation, diagnosis, and clinical course of many lung diseases. Some conditions are more prevalent in women, such as pulmonary arterial hypertension and sarcoidosis. Some life stages-such as pregnancy-are unique to women and can affect the onset and course of lung disease. Clinical presentation may differ as well, such as the higher number of exacerbations experienced by women with cystic fibrosis (CF), more fatigue in women with sarcoidosis, and more difficulty in achieving smoking cessation. Outcomes such as mortality may be different as well, as indicated by the higher mortality in women with CF. In addition, response to therapy and medication safety may also differ by sex, and yet, pharmacogenomic factors are often not adequately addressed in clinical trials. Various aspects of lung/sleep biology and pathobiology are impacted by female sex and female reproductive transitions. Differential gene expression or organ development can be impacted by these biological differences. Understanding these differences is the first step in moving toward precision medicine for all patients. This article is the second part of a state-of-the-art review of specific effects of sex and gender focused on epidemiology, disease presentation, risk factors, and management of selected lung diseases. We review the more recent literature and focus on guidelines incorporating sex and gender differences in pulmonary hypertension, CF and non-CF bronchiectasis, sarcoidosis, restless legs syndrome and insomnia, and critical illness. We also provide a summary of the effects of pregnancy on lung diseases and discuss the impact of sex and gender on tobacco use and treatment of nicotine use disorder.

Plasma TIMP-1 as a sex-specific biomarker for acute lung injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) confers high morbidity and mortality, with a death rate reaching 40%. Pre-clinical and clinical studies have cited sex-specific sex hormones as a critical contributor to divergent immunologic responses. Therefore, exploration of sex and sex hormone roles following lung injury and ARDS development is needed. Tissue inhibitor of metalloproteinase-1 (TIMP-1) was the first-discovered natural collagenase inhibitor and is located exclusively on the X chromosome. This study aimed to evaluate the prognostic role of circulating TIMP-1, and if concentration differences between males and females correlate with the mortality of ARDS patients.

METHODS

Human plasma samples from 100 ARDS patients enrolled in Albuterol to Treat Acute Lung Injury (ALTA) trial on the day of randomization were evaluated. The amount of TIMP-1 was measured using an enzyme-linked immunoassay (ELISA). Area under the receiver operating characteristic (AUROC) was computed to assess the predictive power of TIMP-1 for 30 and 90-day mortality. Chi-squared tests and Kaplan-Meier curves were computed to assess different variables and survival.

RESULTS

AUROC analysis of TIMP-1 and 30-day mortality among females showed that TIMP-1 exhibited an AUC of 0.87 (95% confidence interval [CI] 0.78 to 0.97; P = 0.0014) with an optimal cut-off value of 159.7 ng/mL producing a 100% sensitivity and 74% specificity. For 90-day mortality, AUROC analysis showed an AUC of 0.82 (95% confidence interval [CI] 0.67 to 0.97; P = 0.0016) with a similar cut-off value producing a 90% sensitivity and 76.47% specificity. Stratifying subjects by TIMP-1 concentration as high (≥ 159.7 ng/mL) or low (< 159.7 ng/mL) indicated that high TIMP-1 was associated with increased 30 and 90-day mortality rates (all P < 0.0001). Lastly, high TIMP-1 group was associated with worse other outcomes including ventilator-free days (VFDs) and ICU-free days (all P < 0.05).

CONCLUSION

Circulating TIMP-1 appeared to be a promising biomarker for mortality among females with ARDS. The high TIMP-1 group showed worse VFDs and ICU-free days. Circulating TIMP-1 may be a sex-specific biomarker in the setting of ARDS and could improve ARDS phenotyping as well as provide a novel therapeutic target in females.

Secondary use of data extracted from a clinical information system to assess the adherence of tidal volume and its impact on outcomes

OBJECTIVES

To extract data from clinical information systems to automatically calculate high-resolution quality indicators to assess adherence to recommendations for low tidal volume.

DESIGN

We devised two indicators: the percentage of time under mechanical ventilation with excessive tidal volume (>8mL/kg predicted body weight) and the percentage of patients who received appropriate tidal volume (≤8mL/kg PBW) at least 80% of the time under mechanical ventilation. We developed an algorithm to automatically calculate these indicators from clinical information system data and analyzed associations between them and patients' characteristics and outcomes.

SETTINGS

This study has been carried out in our 30-bed polyvalent intensive care unit between January 1, 2014 and November 30, 2019.

PATIENTS

All patients admitted to intensive care unit ventilated >72h were included.

INTERVENTION

Use data collected automatically from the clinical information systems to assess adherence to tidal volume recommendations and its outcomes.

MAIN VARIABLES OF INTEREST

Mechanical ventilation days, ICU length of stay and mortality.

RESULTS

Of all admitted patients, 340 met the inclusion criteria. Median percentage of time under mechanical ventilation with excessive tidal volume was 70% (23%-93%); only 22.3% of patients received appropriate tidal volume at least 80% of the time. Receiving appropriate tidal volume was associated with shorter duration of mechanical ventilation and intensive care unit stay. Patients receiving appropriate tidal volume were mostly male, younger, taller, and less severely ill. Adjusted intensive care unit mortality did not differ according to percentage of time with excessive tidal volume or to receiving appropriate tidal volume at least 80% of the time.

CONCLUSIONS

Automatic calculation of process-of-care indicators from clinical information systems high-resolution data can provide an accurate and continuous measure of adherence to recommendations. Adherence to tidal volume recommendations was associated with shorter duration of mechanical ventilation and intensive care unit stay.

Tumor Progression Locus 2 Protects against Acute Respiratory Distress Syndrome in Influenza A Virus-Infected Mice

Excessive inflammation in patients with severe influenza disease may lead to acute lung injury that results in acute respiratory distress syndrome (ARDS). ARDS is associated with alveolar damage and pulmonary edema that severely impair gas exchange, leading to hypoxia. With no existing FDA-approved treatment for ARDS, it is important to understand the factors that lead to virus-induced ARDS development to improve prevention, diagnosis, and treatment. We have previously shown that mice deficient in the serine-threonine mitogen-activated protein kinase, Tpl2 (MAP3K8 or COT), succumb to infection with a typically low-pathogenicity strain of influenza A virus (IAV; HKX31, H3N2 [x31]). The goal of the current study was to evaluate influenza A virus-infected Tpl2-/- mice clinically and histopathologically to gain insight into the disease mechanism. We hypothesized that Tpl2-/- mice succumb to IAV infection due to development of ARDS-like disease and pulmonary dysfunction. We observed prominent signs of alveolar septal necrosis, hyaline membranes, pleuritis, edema, and higher lactate dehydrogenase (LDH) levels in the lungs of IAV-infected Tpl2-/- mice compared to wild-type (WT) mice from 7 to 9 days postinfection (dpi). Notably, WT mice showed signs of regenerating epithelium, indicative of repair and recovery, that were reduced in Tpl2-/- mice. Furthermore, biomarkers associated with human ARDS cases were upregulated in Tpl2-/- mice at 7 dpi, demonstrating an ARDS-like phenotype in Tpl2-/- mice in response to IAV infection. IMPORTANCE This study demonstrates the protective role of the serine-threonine mitogen-activated protein kinase, Tpl2, in influenza virus pathogenesis and reveals that host Tpl2 deficiency is sufficient to convert a low-pathogenicity influenza A virus infection into severe influenza disease that resembles ARDS, both histopathologically and transcriptionally. The IAV-infected Tpl2-/- mouse thereby represents a novel murine model for studying ARDS-like disease that could improve our understanding of this aggressive disease and assist in the design of better diagnostics and treatments.

Disparities in Lung-Protective Ventilation in the United States

Background The objective of our study was to determine whether disparities exist in the use of lung-protective ventilation for critically ill mechanically ventilated patients in the United States based on gender, race/ethnicity, or insurance status. Methods This was a secondary data analysis of a prospective multicenter cohort study conducted from 2010 to 2012. The outcome of interest was the proportion of patients receiving tidal volume > 8 mL/kg predicted body weight (PBW). Results There were 1,595 patients in our primary analysis (710 women, 885 men). Women were more likely to receive tidal volumes > 8 mL/kg PBW than men (odds ratio [OR] = 3.42, 95% confidence interval [CI] = 2.67-4.40), a finding largely but not completely explained by gender differences in height. The underinsured were significantly more likely to receive tidal volume > 8 mL/kg PBW than the insured in multivariable analysis (OR = 1.54, 95% CI = 1.16-2.04). The prescription of > 8 mL/kg PBW tidal volume did not differ by racial or ethnic categories. Conclusions In this prospective nationwide cohort of critically ill mechanically ventilated patients, women and the underinsured were less likely than their comparators to receive lung-protective ventilation, with no apparent differences based on race/ethnicity alone.

Comparison of the Outcomes of Patients Starting Mechanical Ventilation in the General Ward Versus the Intensive Care Unit

OBJECTIVE

Mechanical ventilation is sometimes initiated in the general ward (GW) due to the shortage of intensive care unit (ICU) beds. We investigated whether invasive mechanical ventilation (MV) started in the GW affects the patient's prognosis compared with its initiation in the ICU.

METHODS

From January 2016 to December 2018, medical records of patients who started MV in the GW or ICU were collected. The 28-day mortality, ICU mortality, ventilator-free days, and complications related to the ventilator and the ventilator-free days were analyzed as outcomes.

RESULTS

A total of 673 patients were enrolled. Among these, 268 patients (39.8%) started MV in the GW and 405 patients (60.2%) started MV within 24 hours after admittance to the ICU. There was no difference in 28-day mortality between the 2 groups (27.2% versus 27.2%, P = 0.997). In addition, there was no difference between ventilator-related complication rates, ventilator-free days, or the length of hospital stay. A high Acute Physiology and Chronic Health Evaluation II score, the presence of solid tumor, the absence of chronic kidney diseases, and low platelet count were associated with higher 28-day mortality. However, the initiation of MV in the GW was not associated with an increase in 28-day mortality compared with the initiation in the ICU.

CONCLUSIONS

Starting MV in the GW was not a risk factor for 28-day mortality. Therefore, prompt application of a ventilator if medically indicated, regardless of the patient's location, is desirable if a skilled airway team and appropriate monitoring are available.

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.

Gender dimension in cardio-pulmonary continuum

Cardio-pulmonary diseases, which were once regarded as a man's illness, have been one of the leading causes of morbidity and mortality for both men and women in many countries in recent years. Both gender and sex influence the functional and structural changes in the human body and therefore play an important role in disease clinical manifestation, treatment choice, and/or response to treatment and prognosis of health outcomes. The gender dimension integrates sex and gender analysis in health sciences and medical research, however, it is still relatively overlooked suggesting the need for empowerment in the medical research community. Latest advances in the field of cardiovascular research have provided supportive evidence that the application of biological variables of sex has led to the understanding that heart disease in females may have different pathophysiology compared to males, particularly in younger adults. It has also resulted in new diagnostic techniques and a better understanding of symptomatology, while gender analysis has informed more appropriate risk stratification and prevention strategies. The existing knowledge in the pulmonary field shows the higher prevalence of pulmonary disorders among females, however, the role of gender as a socio-cultural construct has yet to be explored for the implementation of targeted interventions. The purpose of this review is to introduce the concept of gender dimension and its importance for the cardiopulmonary continuum with a focus on shared pathophysiology and disease presentation in addition to interrelation with chronic kidney disease. The review presents basic knowledge of what gender dimension means, and the application of sex and gender aspects in cardiovascular medicine with a specific focus on early pulmonary development, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD). Early vascular aging and inflammation have been presented as a potential pathophysiological link, with further interactions between the cardiopulmonary continuum and chronic kidney disease. Finally, implications for potential future research have been provided to increase the impact of gender dimension on research excellence that would add value to everybody, foster toward precision medicine and ultimately improve human health.

Sex-related differences in postoperative complications following elective craniotomy for intracranial lesions: An observational study

INTRODUCTION

The integration of sex-related differences in neurosurgery is crucial for new, possible sex-specific, therapeutic approaches. In neurosurgical emergencies, such as traumatic brain injury and aneurysmal subarachnoid hemorrhage, these differences have been investigated. So far, little is known concerning the impact of sex on frequency of postoperative complications after elective craniotomy. This study investigates whether sex-related differences exist in frequency of postoperative complications in patients who underwent elective craniotomy for intracranial lesion.

MATERIAL AND METHODS

All consecutive patients who underwent an elective intracranial procedure over a 2-year period at our center were eligible for inclusion in this retrospective study. Demographic data, comorbidities, frequency of postoperative complications at 24 hours following surgery and at discharge, and hospital length of stay were compared among females and males.

RESULTS

Overall, 664 patients were considered for the analysis. Of those, 339 (50.2%) were females. Demographic data were comparable among females and males. More females than males suffered from allergic, muscular, and rheumatic disorders. No differences in frequency of postoperative complications at 24 hours after surgery and at discharge were observed among females and males. Similarly, the hospital length of stay was comparable.

CONCLUSIONS

In the present study, no sex-related differences in frequency of early postoperative complications and at discharge following elective craniotomy for intracranial lesions were observed.

Inhaled nitric oxide: role in the pathophysiology of cardio-cerebrovascular and respiratory diseases

Nitric oxide (NO) is a key molecule in the biology of human life. NO is involved in the physiology of organ viability and in the pathophysiology of organ dysfunction, respectively. In this narrative review, we aimed at elucidating the mechanisms behind the role of NO in the respiratory and cardio-cerebrovascular systems, in the presence of a healthy or dysfunctional endothelium. NO is a key player in maintaining multiorgan viability with adequate organ blood perfusion. We report on its physiological endogenous production and effects in the circulation and within the lungs, as well as the pathophysiological implication of its disturbances related to NO depletion and excess. The review covers from preclinical information about endogenous NO produced by nitric oxide synthase (NOS) to the potential therapeutic role of exogenous NO (inhaled nitric oxide, iNO). Moreover, the importance of NO in several clinical conditions in critically ill patients such as hypoxemia, pulmonary hypertension, hemolysis, cerebrovascular events and ischemia-reperfusion syndrome is evaluated in preclinical and clinical settings. Accordingly, the mechanism behind the beneficial iNO treatment in hypoxemia and pulmonary hypertension is investigated. Furthermore, investigating the pathophysiology of brain injury, cardiopulmonary bypass, and red blood cell and artificial hemoglobin transfusion provides a focus on the potential role of NO as a protective molecule in multiorgan dysfunction. Finally, the preclinical toxicology of iNO and the antimicrobial role of NO-including its recent investigation on its role against the Sars-CoV2 infection during the COVID-19 pandemic-are described.

Insights Regarding the Berlin Definition of ARDS from Prospective Observational Studies

The definition of acute respiratory distress syndrome (ARDS), has evolved since it was first described in 1967 by Ashbaugh and Petty to the current "Berlin" definition of ARDS developed in 2012 by an expert panel, that provided clarification on the definition of "acute," and on the cardiac failure criteria. It expanded the definition to include patients receiving non-invasive ventilation, and removed the term "acute lung injury" and added a requirement of patients to be receiving a minimum 5 cmH₂O expiratory pressure.Since 2012, a series of observational cohort studies have generated insights into the utility and robustness of this definition. This review will examine novel insights into the epidemiology of ARDS, failures in ARDS diagnosis, the role of lung imaging in ARDS, the novel ARDS cohort that is not invasively ventilated, lung compliance profiles in patients with ARDS, sex differences that exist in ARDS management and outcomes, the progression of ARDS following initial diagnosis, and the clinical profile and outcomes of confirmed versus resolved ARDS. Furthermore, we will discuss studies that challenge the utility of distinguishing ARDS from other causes of acute hypoxemic respiratory failure (AHRF) and identify issues that may need to be addressed in a revised definition.

Sex Differences in Use of Low Tidal Volume Ventilation in COVID-19-Insights From the PRoVENT-COVID Study

The purpose of this study was to compare and understand differences in the use of low tidal volume ventilation (LTVV) between females and males with acute respiratory distress syndrome (ARDS) related to coronavirus disease 2019 (COVID-19). This is a post-hoc analysis of an observational study in invasively ventilated patients with ARDS related to COVID-19 in 22 ICUs in the Netherlands. The primary endpoint was the use of LTVV, defined as having received a median tidal volume (V_T) ≤6 ml/kg predicted body weight (PBW) during controlled ventilation. A mediation analysis was used to investigate the impact of anthropometric factors, next to the impact of sex per se. The analysis included 934 patients, 251 females and 683 males. All the patients had ARDS, and there were no differences in ARDS severity between the sexes. On the first day of ventilation, females received ventilation with a higher median V_T compared with males [6.8 (interquartile range (IQR) 6.0–7.6 vs. 6.3 (IQR 5.8–6.9) ml/kg PBW; p < 0.001]. Consequently, females received LTVV less often than males (23 vs. 34%; p = 0.003). The difference in the use of LTVV became smaller but persisted over the next days (27 vs. 36%; p = 0.046 at day 2 and 28 vs. 38%; p = 0.030 at day 3). The difference in the use LTVV was significantly mediated by sex per se [average direct effect of the female sex, 7.5% (95% CI, 1.7–13.3%); p = 0.011] and by differences in the body height [average causal mediation effect, −17.5% (−21.5 to −13.5%); p < 0.001], but not by the differences in actual body weight [average causal mediation effect, 0.2% (−0.8 to 1.2%); p = 0.715]. In conclusion, in this cohort of patients with ARDS related to COVID-19, females received LTVV less often than males in the first days of invasive ventilation. The difference in the use of LTVV was mainly driven by an anthropometric factor, namely, body height. Use of LTVV may improve by paying attention to correct titration of V_T, which should be based on PBW, which is a function of body height.

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background

Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies.

Methods

In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality.

Findings

Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference –1·69 [–9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5–8] vs 6 [5–8] cm H₂O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52–23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75–0·86]; p<0·0001).

Interpretation

Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status.

Funding

No funding.

Factors affecting the outcomes in patients with acute respiratory distress syndrome in a tertiary care setting

Purpose

The clinical profile and factors affecting outcomes in acute respiratory distress syndrome (ARDS) from adequately sample-sized Indian studies are still lacking. We aimed to investigate the clinical profile, treatment pattern, outcomes; and to assess factors affecting non-recovery in ARDS patients.

Patients and methods

A retrospective observational study was conducted among adult ARDS patients admitted during five year period (January 2014-December 2018) in a South Indian tertiary care setting. The relevant data were collected from the medical records to the data collection form. The univariate and multivariate logistic regression analyses were conducted to identify the predictors of outcomes using SPSS v20.

Results

A total of 857 participants including 496 males and 361 females with a mean age of 46.86 ± 15.81 years were included in this study. Fever (70.9%), crepitation (58.3%), breathlessness (56.9%), and cough (45%) were the major clinical presentation. Hypertension (25.2%), kidney disease (23.8%), and diabetes (22.3%) were the major comorbidities; and sepsis (37.6%), pneumonia (33.3%), and septic shock (27.5%) were the major etiological factors observed. Antibiotics and steroids were administered to 97.9% and 52.3% of the population, respectively. The recovery rate was 47.49%. The patients with scrub typhus, dengue, pancreatitis, and oxygen supplementation had significantly lower mortality. The factors such as advanced age, sepsis, septic shock, liver diseases, and ventilation requirements were observed to be the independent predictors of non-recovery in ARDS patients.

Conclusion

A comparable recovery rate was observed in our population. Advanced age, sepsis, septic shock, liver diseases, and ventilation requirements were the independent predictors of non-recovery.

Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study

BACKGROUND

One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.

OBJECTIVES

The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.

DESIGN, PATIENTS AND SETTING

This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.

MAIN OUTCOME MEASURES

Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.

RESULTS

This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P < 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P < 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.

CONCLUSION

In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.

TRIAL REGISTRATION

The study was registered at Clinicaltrials.gov, NCT01601223.

Calculated Plasma Volume Status Is Associated With Mortality in Acute Respiratory Distress Syndrome

Supplemental Digital Content is available in the text.

The optimal method to assess fluid overload in acute respiratory distress syndrome is not known, and current techniques have limitations. Plasma volume status has emerged as a noninvasive method to assess volume status and is defined as the percentage alteration from ideal plasma volume. We hypothesized that plasma volume status would suggest the presence of significant excess volume and therefore correlate with mortality in acute respiratory distress syndrome.

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.

Invasiveness of Treatment Is Gender Dependent in Intensive Care: Results From a Retrospective Analysis of 26,711 Cases

BACKGROUND

Health care and outcome of critically ill patients are marked by gender-related differences. Several studies have shown that male patients in intensive care units (ICU) more often receive mechanical ventilation, dialysis, pulmonary arterial catheterization (PAC), and central venous catheterization (CVC). We investigated gender-related differences in ICU treatment and mortality.

METHODS

This retrospective, single-center study analyzed adult ICU patients admitted to the University Medical Center Regensburg between January 2010 and December 2017. Illness severity was measured with the Simplified Acute Physiology Score II (SAPS II) at ICU admission. We evaluated the intensity of ICU treatment according to the implementation of tracheostomy and extracorporeal membrane oxygenation (ECMO). We then assessed gender-related differences in the duration of mechanical ventilation and other invasive monitoring (PAC) and treatment methods (CVC, endotracheal intubation rate, and dialysis). ICU treatment and mortality data were obtained from an electronic data capture system. After adjusting for age, reason for hospitalization, and SAPS II score, we assessed the influence of gender on the intensity of ICU treatment using multivariable logistic regression. Odds ratios (OR) for the logistic regression models and incidence rate ratios (IRR) for the negative binomial regression models were calculated as effect estimates together with the corresponding 95% confidence intervals (95% CI). A P value of <.05 was considered significant.

RESULTS

The study analyzed 26,711 ICU patients (64.8% men). The ICU mortality rate was 8.8%. Illness severity, ICU, and hospital mortality did not differ by gender. Women were older than men (62.6 vs 61.3 years; P < .001) at ICU admission. After multivariable adjustment, men were more likely to undergo tracheostomy (OR = 1.39 [1.26-1.54]), ECMO (OR = 1.37 [1.02-1.83]), dialysis (OR = 1.29 [1.18-1.41]), and PAC insertion (OR = 1.81 [1.40-2.33]) and had a longer duration of mechanical ventilation than women (IRR = 1.07 [1.02-1.12]). The frequency of endotracheal intubation (OR = 1.04 [0.98-1.11]) and placement of CVC (OR = 1.05 [0.98-1.11]) showed no gender-specific differences. Of ICU nonsurvivors, men were more likely to undergo tracheostomy (20.1% vs 15.3%; P = .004) and dialysis (54% vs 46.4%; P < .001) than women and had a longer duration of mechanical ventilation (6.3 vs 5.4 days; P = .015).

CONCLUSIONS

After adjustment for severity of disease and outcome, ICU treatment differs between men and women. Men were more likely than women to undergo tracheostomy and ECMO.

Impact of sex on use of low tidal volume ventilation in invasively ventilated ICU patients-A mediation analysis using two observational cohorts

Background

Studies in patients receiving invasive ventilation show important differences in use of low tidal volume (V_T) ventilation (LTVV) between females and males. The aims of this study were to describe temporal changes in V_T and to determine what factors drive the sex difference in use of LTVV.

Methods and findings

This is a posthoc analysis of 2 large longitudinal projects in 59 ICUs in the United States, the ‘Medical information Mart for Intensive Care III’ (MIMIC III) and the ‘eICU Collaborative Research DataBase’. The proportion of patients under LTVV (median V_T < 8 ml/kg PBW), was the primary outcome. Mediation analysis, a method to dissect total effect into direct and indirect effects, was used to understand which factors drive the sex difference. We included 3614 (44%) females and 4593 (56%) males. Median V_T declined over the years, but with a persistent difference between females (from median 10.2 (9.1 to 11.4) to 8.2 (7.5 to 9.1) ml/kg PBW) vs. males (from median 9.2 [IQR 8.2 to 10.1] to 7.3 [IQR 6.6 to 8.0] ml/kg PBW) (P < .001). In females versus males, use of LTVV increased from 5 to 50% versus from 12 to 78% (difference, –27% [–29% to –25%]; P < .001). The sex difference was mainly driven by patients’ body height and actual body weight (adjusted average causal mediation effect, –30% [–33% to –27%]; P < .001, and 4 [3% to 4%]; P < .001).

Conclusions

While LTVV is increasingly used in females and males, females continue to receive LTVV less often than males. The sex difference is mainly driven by patients’ body height and actual body weight, and not necessarily by sex. Use of LTVV in females could improve by paying more attention to a correct calculation of V_T, i.e., using the correct body height.

Outcomes With Severe Blastomycosis and Respiratory Failure in the United States

BACKGROUND

Outcomes of patients with severe pulmonary blastomycosis requiring mechanical ventilation (MV) are not well understood in the modern era. Limited historical case series reported 50-90% mortality in patients with acute respiratory distress syndrome caused by blastomycosis. The objective of this large retrospective cohort study was to describe the risk factors and outcomes of patients with severe pulmonary blastomycosis.

METHODS

We performed a retrospective cohort analysis utilizing the Nationwide Inpatient Sample from 2006-2014. Patients aged >18 years with a diagnosis of blastomycosis who received MV were included.

RESULTS

There were 1848 patients with a diagnosis of blastomycosis included in the study. Of these, 219 (11.9%) underwent MV with a mortality rate of 39.7% compared with 2.5% in patients not requiring ventilatory support (P < .01). The median (IQR) time to death for patients requiring MV was 12 (8-16) days. The median length of hospital stay for survivors of MV was 22 (14-37) days. The rate of MV was higher for patients treated in teaching hospitals (63.4% vs 57.2%, P = .05) and lower for those receiving care at a rural hospital (12.3% vs 17.2%, P = .04). In a multivariate model, female gender was associated with increased risk of mortality (OR, 1.84; 95% CI, 1.06-3.20; P = .03) as was increasing patient age (10-year age increase OR, 1.64; 95% CI, 1.33-2.02; P < .01).

CONCLUSIONS

In the largest published cohort of patients with blastomycosis, mortality for patients on MV is high at ~40%, 16-fold higher than those without MV.

Concentrated Secretome of Adipose Stromal Cells Limits Influenza A Virus-Induced Lung Injury in Mice

Despite vaccination and antivirals, influenza remains a communicable disease of high burden, with limited therapeutic options available to patients that develop complications. Here, we report the development and preclinical characterization of Adipose Stromal Cell (ASC) concentrated secretome (CS), generated by process adaptable to current Good Manufacturing Practices (cGMP) standards. We demonstrate that ASC-CS limits pulmonary histopathological changes, infiltration of inflammatory cells, protein leak, water accumulation, and arterial oxygen saturation (spO2) reduction in murine model of lung infection with influenza A virus (IAV) when first administered six days post-infection. The ability to limit lung injury is sustained in ASC-CS preparations stored at −80 °C for three years. Priming of the ASC with inflammatory factors TNFα and IFNγ enhances ASC-CS ability to suppress lung injury. IAV infection is associated with dramatic increases in programmed cell death ligand (PDL1) and angiopoietin 2 (Angpt2) levels. ASC-CS application significantly reduces both PDL1 and Angpt2 levels. Neutralization of PDL1 with anti-mouse PDL1 antibody starting Day6 onward effectively ablates lung PDL1, but only non-significantly reduces Angpt2 release. Most importantly, late-phase PDL1 neutralization results in negligible suppression of protein leakage and inflammatory cell infiltration, suggesting that suppression of PDL1 does not play a critical role in ASC-CS therapeutic effects.

Highlights from the Respiratory Failure and Mechanical Ventilation 2020 Conference

The Respiratory Intensive Care Assembly of the European Respiratory Society organised the first Respiratory Failure and Mechanical Ventilation Conference in Berlin in February 2020. The conference covered acute and chronic respiratory failure in both adults and children. During this 3-day conference, patient selection, diagnostic strategies and treatment options were discussed by international experts. Lectures delivered during the event have been summarised by Early Career Members of the Assembly and take-home messages highlighted.

During #RFMV2020, patient selection, diagnostic strategies and treatment options were discussed by international experts. This review summarises the most important take-home messages.https://bit.ly/3murkoa

Sex- or Gender-specific Differences in the Clinical Presentation, Outcome, and Treatment of SARS-CoV-2

This review describes the sex and gender differences in COVID-19 presentation, treatment, and outcomes. We discuss the differences between the sexes in susceptibility to infection, the role of sex chromosomes on the body's immunologic response and the influence of hormones on the body's response to the virus. Additionally, the sex differences in clinical and laboratory presentation, complications of infection and outcomes, as well as differences in response to treatment and prevention are reviewed.

Prevalence and Outcomes of Acute Hypoxaemic Respiratory Failure in Wales: The PANDORA-WALES Study

BACKGROUND

We aimed to identify the prevalence of acute hypoxaemic respiratory failure (AHRF) in the intensive care unit (ICU) and its associated mortality. The secondary aim was to describe ventilatory management as well as the use of rescue therapies.

METHODS

Multi-centre prospective study in nine hospitals in Wales, UK, over 2-month periods. All patients admitted to an ICU were screened for AHRF and followed-up until discharge from the ICU. Data were collected from patient charts on patient demographics, clinical characteristics, management and outcomes.

RESULTS

Out of 2215 critical care admissions, 886 patients received mechanical ventilation. A total of 197 patients met inclusion criteria and were recruited. Seventy (35.5%) were non-survivors. Non-survivors were significantly older, had higher SOFA scores and received more vasopressor support than survivors. Twenty-five (12.7%) patients who fulfilled the Berlin definition of acute respiratory distress syndrome (ARDS) during the ICU stay without impact on overall survival. Rescue therapies were rarely used. Analysis of ventilation showed that median Vt was 7.1 mL/kg PBW (IQR 5.9-9.1) and 21.3% of patients had optimal ventilation during their ICU stay.

CONCLUSIONS

One in four mechanically ventilated patients have AHRF. Despite advances of care and better, but not optimal, utilisation of low tidal volume ventilation, mortality remains high.

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome: insights from the LUNG SAFE study

Background

Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study.

Methods

In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO₂ > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO₂ ≥ 0.60 during hyperoxemia).

Results

Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO₂ < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO₂ use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO₂ use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO₂. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO₂ use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO₂ use, compared to 39% in a propensity-matched sample of normoxemic (PaO₂ 55–100 mmHg) patients (P = 0.47).

Conclusions

Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort.

Trial registration

LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073

ERS International Congress, Madrid, 2019: highlights from the Respiratory Intensive Care Assembly

The Respiratory Intensive Care Assembly of the European Respiratory Society is delighted to present the highlights from the 2019 International Congress in Madrid, Spain. We have selected four sessions that discussed recent advances in a wide range of topics: from acute respiratory failure to cough augmentation in neuromuscular disorders and from extra-corporeal life support to difficult ventilator weaning. The subjects are summarised by early career members in close collaboration with the Assembly leadership. We aim to give the reader an update on the most important developments discussed at the conference. Each session is further summarised into a short list of take-home messages.