Hospital Incidence and Outcomes of the Acute Respiratory Distress Syndrome Using the Kigali Modification of the Berlin Definition

Clinical Performance of Spo2/Fio2 and Pao2/Fio2 Ratio in Mechanically Ventilated Acute Respiratory Distress Syndrome Patients: A Retrospective Study

OBJECTIVES

The present study aims to evaluate the severity classification of acute respiratory distress syndrome (ARDS) in mechanically ventilated patients according to peripheral oxygen saturation by pulse oximetry (Spo2)/Fio2 ratio compared with Pao2/Fio2 ratio and the relationship between Spo2/Fio2 ratio and venous admixture.

DESIGN

Retrospective observational study.

SETTING

Medical-surgical ICU.

PATIENTS

A cohort of 258 mechanically ventilated patients with ARDS already enrolled in previous studies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Gas exchange, Spo2, and respiratory mechanics were measured on ICU admission and during the positive end-expiratory pressure (PEEP) trial. Radiological data from CTs were used to compute lung recruitability and to assess different lung compartments. A nonlinear association was found between Spo2/Fio2 and Pao2/Fio2. Considering the possible confounding factors of the pulse oximeter on the relationship between Spo2/Fio2 and Pao2/Fio2 ratio, arterial pH, and Paco2 had no effect. Spo2/Fio2 and Pao2/Fio2 ratio demonstrated a moderate agreement in classifying ARDS severity (intraclass correlation coefficient = 0.63). Between the correspondent classes according to Spo2/Fio2 vs. Pao2/Fio2 ratio-derived severity classifications, there was no difference in terms of respiratory mechanics, gas exchange, lung radiological characteristics and mortality in ICU, and within two levels of PEEP. A Spo2/Fio2 ratio less than 235 was able to detect 89% of patients with a venous admixture greater than 20%, similarly to a Pao2/Fio2 ratio less than 200.

CONCLUSIONS

Spo2/Fio2 ratio can detect oxygenation impairment and classify ARDS severity similarly to Pao2/Fio2 ratio in a more rapid and handy way, even during a PEEP trial. However, our results may not be applicable to different patient populations; in fact, the pulse oximeter is merely a monitoring device and the information should be personalized by the physician on the patient's characteristics and conditions.

The Central Role of Cytochrome P450 Reductase (CPR) in Hyperoxic Lung Injury

INTRODUCTION

Hyperoxic lung injury results from excessive supplemental oxygen therapy in conditions such as bronchopulmonary dysplasia (BPD) in preterm infants and acute respiratory distress syndrome (ARDS) in adults. This review explores the role of cytochrome P450 reductase (CPR) in hyperoxic lung injury.

AREAS COVERED

Hyperoxia induces the production of reactive oxygen species in excessive amounts, overwhelming the body's antioxidant defenses and exacerbating lung injury in ARDS/BPD. This review examines the differential roles of CPR-dependent enzymes in the context of hyperoxic lung injury. Additionally, we highlight the potential of targeting CPR to study mechanisms of lung injury and leverage gene-editing technologies to deepen our understanding of CPR-mediated pathways. This review consolidates existing knowledge on CPR-dependent processes and their roles in hyperoxic lung injury, based on a literature search conducted in the PubMed database for studies published between 1988 and 2024.

EXPERT OPINION

This review emphasizes the need for a deeper understanding of disease mechanisms, particularly CPR-mediated pathways. As a regulatory hub for ROS modulation and enzyme activity, CPR represents a promising target, offering a unified strategy to mitigate hyperoxic lung injury and improve outcomes in BPD/ARDS.

A narrative review on the future of ARDS: evolving definitions, pathophysiology, and tailored management

Acute respiratory distress syndrome (ARDS) is a severe complication of critical illness, characterized by bilateral lung infiltrates and hypoxemia. Its clinical and pathophysiological heterogeneity poses challenges for both diagnosis and treatment. This review outlines the evolution of ARDS definitions, discusses the underlying pathophysiology of ARDS, and examines the clinical implications of its heterogeneity. Traditional ARDS definitions required invasive mechanical ventilation and relied on arterial blood gas measurements to calculate the PaO2/FiO2 ratio. Recent updates have expanded these criteria to include patients receiving noninvasive respiratory support, such as high-flow nasal oxygen, and the adoption of the SpO2/FiO2 ratio as an alternative to the PaO2/FiO2 ratio. While these changes broaden the diagnostic criteria, they also introduce additional complexity. ARDS heterogeneity-driven by varying etiologies, clinical subphenotypes, and underlying biological mechanisms-highlights the limitations of a uniform management approach. Emerging evidence highlights the presence of distinct ARDS subphenotypes, each defined by unique molecular and clinical characteristics, offering a pathway to more precise therapeutic targeting. Advances in omics technologies-encompassing genomics, proteomics, and metabolomics-are paving the way for precision-medicine approaches with the potential to revolutionize ARDS management by tailoring interventions to individual patient profiles. This paradigm shift from broad diagnostic categories to precise, subphenotype-driven care holds promise for redefining the landscape of treatment for ARDS and, ultimately, improving outcomes in this complex, multifaceted syndrome.

Limitations of SpO2 / FiO2-ratio for classification and monitoring of acute respiratory distress syndrome-an observational cohort study

BACKGROUND

The ratio of pulse-oximetric peripheral oxygen saturation to fraction of inspired oxygen (SpO2/FiO2) has been proposed as additional hypoxemia criterion in a new global definition of acute respiratory distress syndrome (ARDS). This study aims to evaluate the clinical and theoretical limitations of the SpO2/FiO2-ratio when using it to classify patients with ARDS and to follow disease progression.

METHODS

Observational cohort study of ARDS patients from three high-resolution Intensive Care Unit databases, including our own database ICU Cockpit, MIMIC-IV (Version 3.0) and SICdb (Version 1.0.6). Patients with ARDS were identified based on the Berlin criteria or ICD 9/10-codes. Time-matched datapoints of SpO2, FiO2 and partial pressure of oxygen in arterial blood (PaO2) were created. Severity classification followed the thresholds for SpO2/FiO2 and PaO2/FiO2 of the newly proposed global definition.

RESULTS

Overall, 708 ARDS patients were included in the analysis. ARDS severity was misclassified by SpO2/FiO2 in 33% of datapoints, out of which 84% were classified as more severe. This can be partially explained by imprecision of SpO2 measurement and equation used to transform SpO2/FiO2 to PaO2/FiO2. A high dependence of SpO2/FiO2-ratio on FiO2 settings was found, leading to major treatment effect and limited capability for tracking change in ARDS severity, which was achieved in less than 20% of events.

CONCLUSIONS

The use of SpO2/FiO2 interchangeably with PaO2/FiO2 for severity classification and monitoring of ARDS is limited by its inadequate trending ability and high dependence on FiO2 settings, which may influence treatment decisions and patient selection in clinical trials.

Molecular phenotypes of critical illness confer prognostic and biological enrichment in sub-Saharan Africa: a prospective cohort study from Uganda

The generalisability of critical illness molecular phenotypes to low- and middle-income countries (LMICs) is unknown. We show that molecular phenotypes derived in high-income countries (hyperinflammatory and hypoinflammatory, reactive and uninflamed) stratify sepsis patients in Uganda by physiological severity, mortality risk and dysregulation of key pathobiological domains. A classifier model including data available at the LMIC bedside modestly discriminated phenotype assignment (area under the receiver operating characteristic curve (AUROC) 0.80, 95% CI 0.71 to 0.90 for hyperinflammatory vs hypoinflammatory; AUROC 0.74, 95% CI 0.65 to 0.83 for reactive vs uninflamed). Our findings highlight the potential for a globally relevant, clinicomolecular classification of critical illness and may support the inclusion of diverse populations in phenotype-targeted critical care trials. Improved laboratory capacity and access to rapid biomarker assays are likely necessary to optimise phenotype stratification in LMIC settings.

The Protective Effects of Sivelestat Sodium on the Basis of Corticosteroid Therapy in Patients With Moderate-to-Severe Acute Respiratory Distress Syndrome

Objective: We aimed to evaluate the protective effects of sivelestat sodium on the basis of corticosteroid therapy in patients with moderate-to-severe acute respiratory distress syndrome (ARDS). Methods: We retrospectively investigated 127 patients with confirmed moderate-to-severe ARDS treated in the intensive care unit (ICU) at Dazhou Central Hospital. Patients were divided into the control group (corticosteroids alone) and the combination therapy of steroids and sivelestat sodium (CTSSS) group according to the therapeutic interventions. The primary outcome was in-hospital mortality. And the baseline characteristics and laboratory findings of patients were collected for analysis. Results: The overall mortality rate in 127 patients was 48.8%. There was no statistically significant difference in in-hospital mortality between the CTSSS group and the control group (45.3% vs. 56.1%). In the subgroup of patients aged < 80 years or with an Acute Physiology and Chronic Health Evaluation (APACHE) II score < 30, CTSSS could reduce the risk of mortality (odds ratio [OR] = 0.41, 95% confidence interval [CI], 0.17-0.96, p=0.041; OR = 0.31, 95% CI, 0.13-0.77, p=0.012; respectively). Among patients aged 80 years or older, those with CTSSS exhibited a significantly elevated risk of mortality (OR = 13; 95% CI, 1.20-140.73; p=0.035). Conclusion: Compared with corticosteroids alone, CTSSS could improve oxygenation index, increase lymphocyte count, protect extrapulmonary organs and reduce in-hospital mortality rate in patients with moderate-to-severe ARDS in specific subgroups (age < 80 years or APACHE II score < 30). It might be advisable to avoid CTSSS in moderate-to-severe ARDS patients aged 80 years or older. Prospective studies involving larger sample sizes are needed to verify these findings.

Adaptive Design for Phase II/III Platform Trial of Lassa Fever Therapeutics

The current recommendation for treating Lassa fever with ribavirin is supported only by weak evidence. Given the persistent effects in areas with endemic transmission and epidemic potential, there is an urgent need to reassess ribavirin and investigate other potential therapeutic candidates; however, a robust clinical trial method adapted to Lassa fever epidemiology has not yet been established. We propose an adaptive phase II/III multicenter randomized controlled platform trial that uses a superiority framework with an equal allocation ratio and accounts for challenges selecting the primary end point and estimating the target sample size by using an interim analysis.

Evaluating the impact of ESICM 2023 guidelines and the new global definition of ARDS on clinical outcomes: insights from MIMIC-IV cohort data

BACKGROUND

In 2023, the European Society of Intensive Care Medicine (ESICM) recommended updated criteria for acute respiratory distress syndrome (ARDS). In 2024, Matthay et al. updated the global ARDS definition in AJRCCM, titled "A New Global Definition of Acute Respiratory Distress Syndrome." However, the impact of this new definition on ARDS treatments is currently unknown.

OBJECTIVE

This study aims to determine the effect of the new ARDS definition on patients with hypoxemic respiratory failure and study the heterogeneity of patients in the new definition to guide treatment.

METHODS

Clinical consultation data from the Medical Information Mart for Intensive Care IV database were extracted using Structured Query Language based on the PostgreSQL tool (version 10.0). Data were analyzed using Python (version 3.9) and the deep learning framework Pytorch. Kaplan-Meier survival analysis was used to compare survival between the old and new definitions. A hierarchical clustering approach was applied to identify potential ARDS clinical subtypes.

RESULTS

The new definition diagnosed ARDS earlier and included individuals with lower mortality rates compared with the Berlin definition. Patients meeting the new definition but not the Berlin criteria exhibited a favorable response to non-invasive ventilation strategies (p = 0.009). The XGBoost classifier, trained to predict subphenotypes, achieved an AUC of 0.88 ± 0.02 on the training set. Additionally, mortality was significantly associated with patients with hypoxemia compared with survivors, particularly regarding respiratory parameters. Easily accessible metrics, such as respiratory rate and urea nitrogen (BUN), can help diagnose ARDS in high-risk populations in resource-limited settings.

CONCLUSIONS

The new ARDS definition offers advantages in earlier detection, more accurate grading, and more precise diagnosis in resource-limited settings compared with the Berlin definition. This study also established a robust prediction model for early ARDS identification, improving the patient prognosis and reducing the mortality rate.

Point-of-Care Ultrasound in Resource-Limited Settings

Point-of-care ultrasound (POCUS) bridges diagnostic gaps across the continuum of care worldwide and is a particularly potent tool in resource-limited settings (RLS). To capture the scope of its current impact in RLS, this narrative review of POCUS use in public health, primary care, outpatient specialty, pre-hospital, and palliative care settings discusses its use in reducing diagnostic health care inequities. Disease-specific protocols, longitudinal training, quality assurance, and task shifting are key to robust expansion of POCUS in RLS.

Definitions of Acute Respiratory Distress Syndrome: Present Recommendations and Challenges

Acute respiratory distress syndrome (ARDS) is an acute inflammatory process resulting in diffuse lung injury precipitated by an underlying risk factor. However, current definitions may pose barriers to the accurate diagnosis of this syndrome. These include changes in risk factors and associated disease evolution of ARDS, changes in contemporary clinical practice, and access to diagnostic tools required to diagnose ARDS in resource-limited settings. A consensus conference has proposed changes for an expanded global definition of ARDS. In this review article, we review challenges in defining ARDS and present recommendations of the global definition of ARDS.

Operationalizing the New Global Definition of ARDS: A Retrospective Cohort Study From South Africa

BACKGROUND

A proposed new global definition of ARDS seeks to update the Berlin definition and account for nonintubated ARDS and ARDS diagnoses in resource-variable settings.

RESEARCH QUESTION

How do ARDS epidemiologic characteristics change with operationalizing the new global definition of ARDS in a resource-limited setting?

STUDY DESIGN AND METHODS

We performed a real-use retrospective cohort study among adult patients meeting criteria for the Berlin definition of ARDS or the global definition of ARDS at ICU admission in two public hospitals in the KwaZulu-Natal Department of Health, South Africa, from January 2017 through June 2022.

RESULTS

Among 5,760 adults (aged ≥ 18 years) admitted to the ICU, 2,027 patients (35.2%) met at least one ARDS definition, including 1,218 patients meeting the Berlin definition of ARDS (60.1% of all ARDS diagnoses) and 809 new diagnoses of the global definition of ARDS that were not captured by the Berlin definition alone (39.9% of all ARDS diagnoses and 14.0% of all ICU admissions). After adjustment for hospital-level factors, patients who met only the global definition of ARDS criteria (ie, who would not have been captured by the Berlin definition) showed no statistically significant ICU mortality difference vs patients with ARDS according to the Berlin definition (21.7% [95% CI, 18.9%-24.4%] vs 23.8% [95% CI, 21.5%-26.2%]; OR, 0.88 [95% CI, 0.70-1.10]; P = .25). In prespecified exploratory subgroup analyses, patients without COVID-19 who met only the criteria for the global definition of ARDS showed reduced ICU mortality (14.2% [95% CI, 11.6%-16.9%] vs 22.2% [95% CI, 19.8%-24.6%]; OR, 0.58 [95% CI, 0.45-0.75]; P < .0005) compared with patients without COVID-19 who met the Berlin definition for ARDS.

INTERPRETATION

The new global definition of ARDS captures a significant proportion of patients who would not have been included by the Berlin definition alone. These additional patients with ARDS may have heterogenous patterns of outcomes among diagnostic subgroups, including by COVID-19 status, compared with patients with ARDS according to the Berlin definition.

Pharmacological mechanisms of traditional Chinese medicine against acute lung injury: From active ingredients to herbal formulae

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are the leading causes of acute respiratory failure in many critical diseases and are among the main respiratory diseases with high clinical mortality. The global outbreak of coronavirus disease 2019 (COVID-19) can cause severe ARDS, resulting in a steep rise in the number of patient deaths. Therefore, it is important to explore the pathogenesis of ALI and find effective therapeutic agents. In recent years, thanks to modern biomedical tools, some progress has been made in the application of traditional Chinese medicine (TCM) treatment principles based on syndromic differentiation and holistic concepts in clinical and experimental studies of ALI. More and more TCM effective components and formulae have been verified to have significant curative effects, which have a certain guiding significance for clinical practice.

PURPOSE

It is hoped to provide reference for the clinical research of ALI/ARDS and provide theoretical basis and technical support for the scientific application of TCM in respiratory related diseases.

METHODS

We performed a literature survey using traditional books of Chinese medicine and online scientific databases including PubMed, Web of Science, Google Scholar, ScienceDirect, China National Knowledge Infrastructure (CNKI), and others up to January 2023.

RESULTS

In recent years, thanks to modern biomedical tools, some progress has been made in the application of TCM treatment principles based on syndromic differentiation and holistic concepts in clinical and experimental studies of ALI. This paper mainly reviews the research progress of ALI/ARDS mechanism, the understanding of its etiology and pathogenesis by TCM, and the therapeutic effects of TCM formulae and active ingredients of Chinese medicine. A large number of studies have shown that the effective components and formulae of TCM can prevent or treat ALI/ARDS in vivo and in vitro experiments.

CONCLUSION

TCM effective components and formulae play an important role in the prevention and treatment of ALI/ARDS through multiple approaches and multiple targets, and provide necessary theoretical support for the further development and utilization of TCM resources.

Acute respiratory distress syndrome

The understanding of acute respiratory distress syndrome (ARDS) has evolved greatly since it was first described in a 1967 case series, with several subsequent updates to the definition of the syndrome. Basic science advances and clinical trials have provided insight into the mechanisms of lung injury in ARDS and led to reduced mortality through comprehensive critical care interventions. This review summarizes the current understanding of the epidemiology, pathophysiology, and management of ARDS. Key highlights include a recommended new global definition of ARDS and updated guidelines for managing ARDS on a backbone of established interventions such as low tidal volume ventilation, prone positioning, and a conservative fluid strategy. Future priorities for investigation of ARDS are also highlighted.

Risk factors for in-hospital mortality in older patients with acute respiratory distress syndrome due to COVID-19: a retrospective cohort study

BACKGROUND

Advancing age is associated with an increase in mortality among patients with acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19). This study aimed to determine risk factors for in-hospital mortality in patients over 60 years old with COVID-19-related ARDS (C-ARDS).

METHODS

This was an observational, analytical, retrospective study conducted on a cohort that included all patients aged 60 years or older diagnosed with COVID-ARDSwho were admitted to a high-complexity hospital in Bogotá, Colombia, between March 2020 and July 2021.

RESULTS

A total of 1563 patients were included in the analysis, with a median age of 73 years (interquartile range [IQR]: 67-80) and 811 deaths (51.8%). Independent risk factors for in-hospital mortality were identified as follows: patients aged 71-80 [OR 1.87 (95% CI 1.33-2.64)], age > 80 [OR 8.74 (95% CI 5.34-14.31)], lactate dehydrogenase (LDH) [OR 1.009 (95% CI 1.003-1.0015)], severe C-ARDS [OR 2.16 (95% CI 1.50-3.11)], use of invasive mechanical ventilation (IMV) [OR 12.94 (95% CI 9.52-17.60)], and use of steroids [OR 1.49 (95% CI 1.09-2.03)]. In patients over 80 years of age (n = 388), the primary risk factor associated with in-hospital mortality was the use of IMV (n = 76) [OR 6.26 (95% CI 2.67-14.69)], resulting in an in-hospital mortality rate of 89.4% (n = 68) when this therapy was implemented.

CONCLUSIONS

The primary risk factors for in-hospital mortality in patients older than 60 years were age, the use of IMV, the severity of C-ARDS, use of steroids and elevated LDH values. Among patients older than 80 years, the main risk factor for in-hospital mortality was the use of IMV. In cases of C-ARDS in older patients, the decision to initiate IMV should always be individualized; therefore, the use of alternative oxygen delivery systems as the first-line approach can be considered.

Combined lung and diaphragm ultrasound predicts extubation outcomes in ARDS: a prospective study

BACKGROUND

Extubation failure is a crucial issue for acute respiratory distress syndrome (ARDS). Ultrasound of the lung and diaphragm is individually valuable for predicting extubation outcomes. We aimed to determine whether combined lung and diaphragmatic ultrasound could improve the accuracy of predicting the extubation of ARDS patients.

METHODS

This was a prospective cohort study of ARDS patients who were ready for extubation. The lung ultrasound score (LUS), diaphragmatic displacement (DD), diaphragm thickening fraction (DTF), and diaphragmatic-rapid shallow breathing index (D-RSBI) were measured at the end of the spontaneous breathing trial. The primary outcome was extubation success. Logistic regression was used to combine these indicators, and the predictive performance of the single and combined indicators was evaluated through receiver operating characteristic (ROC) curves, the Hosmer-Lemeshow Ĉ-test, and the Brier score. Multivariate logistic regression was used to determine the association between combined ultrasound indicators and extubation success.

RESULTS

This study enrolled 132 eligible patients from January 2019 to December 2022. A total of 71% (94/132) of patients were successfully extubated from mechanical ventilation. The combination of LUS and D-RSBI had the largest area under the ROC curves, the lowest Brier score, and the greatest calibration. After formula transformation, LUS + 2.43 × D-RSBI ≤ 14.273 was significantly associated with extubation success in ARDS patients.

CONCLUSIONS

In ARDS patients receiving mechanical ventilation, the combination of LUS and D-RSBI was more accurate than a single parameter alone in predicting extubation outcomes. This combined approach could help refine extubation protocols in critical care. Clinical trial registration This study is registered online with the Chinese Clinical Trial Registry (ChiCTR), http://www.chictr.org.cn , ChiCTR1800019340 (Registration time: 2018/11/06).

Highlights from the Respiratory Failure and Mechanical Ventilation Conference 2024

The Respiratory Intensive Care Assembly of the European Respiratory Society gathered in Berlin to organise the third Respiratory Failure and Mechanical Ventilation Conference in February 2024. The conference covered key points of acute and chronic respiratory failure in adults. During the 3-day conference ventilatory strategies, patient selection, diagnostic approaches, treatment and health-related quality of life topics were addressed by a panel of international experts. In this article, lectures delivered during the event have been summarised by early career members of the Assembly and take-home messages highlighted.

Revisiting ARDS Classification: Are We There Yet?

How to cite this article: Mishra S. Revisiting ARDS Classification: Are We There Yet? Indian J Crit Care Med 2024;28(10):899-900.

Author Response: Oxygenation Indices in Adult COVID ARDS Patients

How to cite this article: Vadi SMR, Sanwalka N, Suthar D. Author Response: Oxygenation Indices in Adult COVID ARDS Patients. Indian J Crit Care Med 2024;28(9):889.

Midline catheters for blood gas and acid/base monitoring in critical patients: A prospective observational study

BACKGROUND

Arterial lines and central venous catheter (CVC) allow to monitor patients' acid-base status and gas exchange. Their placement and maintenance may however be burdened by severe complications. Midline Catheters (MC) are peripheral venous accesses that are less invasive and easier to insert compared to CVC and arterial lines.

METHODS

A prospective observational study was performed including stabilized critical patients with clinical indication to midline positioning before intensive care unit (ICU) discharge. The primary aim was to assess if venous sampling from MCs can be a reliable alternative to CVC for pH and CO2 monitoring. The secondary aim was to evaluate the correlation between samplings from MC, CVC and arterial line with regards to pH, carbon dioxide tension (pCO2), lactates and electrolytes. Three samples from CVC, arterial line and MC were collected simultaneously. Agreement and correlation of the studied parameters between different sampling sites were explored.

RESULTS

40 patients were included in the analysis. A good agreement for pH and pCO2 was recorded between MC and CVC: mean differences were 0.001 (95% CI -0.006 to 0.007) and 0.7 (-0.1 to 1.5), percentage error 0.4% and 11.2%, respectively. Correlation between MC and both central venous and arterial samples for pH, pCO2, lactates and electrolytes was found to be moderate-to-strong (Pearson's R coefficient range 0.59-0.99, p < 0.001 for all these parameters).

CONCLUSIONS

In stabilized critical patients, midline catheters represent a reliable alternative to CVC and arterial lines to monitor acid-base disturbances, CO2 levels and electrolytes. The present findings add to the known advantages of MC, which might be considered a first-line vascular access for non-critical or stabilized patients who do not require infusion of vesicant or irritant drugs.

Subphenotypes in Acute Respiratory Distress Syndrome: Universal Steps Toward Treatable Traits

Patients with acute respiratory distress syndrome (ARDS) have severe respiratory impairment requiring mechanical ventilation resulting in high mortality. Despite extensive research, no effective pharmacological interventions have been identified in unselected ARDS, which has been attributed to the considerable heterogeneity. The identification of more homogeneous subgroups through phenotyping has provided a novel method to improve our pathophysiological understanding, trial design, and, most importantly, patient care through targeted interventions. The objective of this article is to outline a structured, stepwise approach toward identifying and classifying heterogeneity within ARDS and subsequently derive, validate, and integrate targeted treatment options. We present a 6-step roadmap toward the identification of effective phenotype-targeted treatments: development of distinct and reproducible subphenotypes, derivation of a possible parsimonious bedside classification method, identification of possible interventions, prospective validation of subphenotype classification, testing of subphenotype-targeted intervention prospectively in randomized clinical trial (RCT), and finally implementation of subphenotype classification and intervention in guidelines and clinical practice. Based on this framework, the current literature was reviewed. Respiratory physiology, lung morphology, and systemic inflammatory biology subphenotypes were identified. Currently, lung morphology and systemic inflammatory biology subphenotypes are being tested prospectively in RCTs.

Risk factors for in-hospital mortality in recipients of allogeneic hematopoietic stem cell transplantation with acute respiratory distress syndrome: a retrospective study based on the 2023 new definition of acute respiratory distress syndrome

INTRODUCTION

ARDS (acute respiratory distress syndrome) is the most severe form of acute hypoxic respiratory failure. Most studies related to ARDS have excluded patients with hematologic diseases, let alone allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Numerous patients experiencing severe hypoxic respiratory failure do not meet the Berlin definition due to the limitations of diagnosis and treatment. A new definition of ARDS, remove some diagnosis restrictions, was proposed in 2023. Based on the 2023 new definition of ARDS, we investigated the clinical features of ARDS in allo-HSCT recipients and reported risk factors for in-hospital mortality in allo-HSCT recipients defined by the Berlin definition and the new definition of ARDS respectively.

METHODS

From Jan 2016 to Dec 2020, 135 allo-HSCT recipients identified with the new definition and 87 identified with the Berlin definition at three teaching hospitals were retrospectively included in this study. Variables (demographic information, characteristics of hematologic disease and ARDS episode, laboratory tests and SOFA score) with P < 0.05 in univariate logistic regression analysis were included in multivariate stepwise logistic regression analysis. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were reported.

RESULTS

Under the new definition, SOFA score (OR = 1.351, 95% CI: 1.146-1.593, P < 0.01) were found as an independent risk factor for in-hospital mortality in ARDS after allo-HSCT, while SpO2/FiO2 (OR = 0.984, 95% CI: 0.972-0.996, P < 0.01) was a protective factor. The infusion of peripheral-derived stem cells was found to be a protective factor against in-hospital mortality in post-transplantation ARDS compared with the infusion of bone marrow-derived stem cells (OR = 0.726, 95% CI: 0.164-3.221, P = 0.04). Under the Berlin definition, PaO2/FiO2 (OR = 0.977, 95% CI: 0.961-0.993, P = 0.01, lactate (OR = 7.337, 95% CI: 1.313-40.989, P < 0.01) and AST (OR = 1.165, 95% CI: 1.072-1.265, P < 0.01) were independently associated with in-hospital mortality.

CONCLUSION

These prognostic risk factors we found in allo-HSCT recipients may contribute to closer monitoring and ARDS prevention strategies. These findings require confirmation in prospective, large sample size studies.

Diagnostic accuracy of lung ultrasound in diagnosis of ARDS and identification of focal or non-focal ARDS subphenotypes: a systematic review and meta-analysis

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a life-threatening respiratory condition with high mortality rates, accounting for 10% of all intensive care unit admissions. Lung ultrasound (LUS) as diagnostic tool for acute respiratory failure has garnered widespread recognition and was recently incorporated into the updated definitions of ARDS. This raised the hypothesis that LUS is a reliable method for diagnosing ARDS.

OBJECTIVES

We aimed to establish the accuracy of LUS for ARDS diagnosis and classification of focal versus non-focal ARDS subphenotypes.

METHODS

This systematic review and meta-analysis used a systematic search strategy, which was applied to PubMed, EMBASE and cochrane databases. Studies investigating the diagnostic accuracy of LUS compared to thoracic CT or chest radiography (CXR) in ARDS diagnosis or focal versus non-focal subphenotypes in adult patients were included. Quality of studies was evaluated using the QUADAS-2 tool. Statistical analyses were performed using "Mada" in Rstudio, version 4.0.3. Sensitivity and specificity with 95% confidence interval of each separate study were summarized in a Forest plot.

RESULTS

The search resulted in 2648 unique records. After selection, 11 reports were included, involving 2075 patients and 598 ARDS cases (29%). Nine studies reported on ARDS diagnosis and two reported on focal versus non-focal ARDS subphenotypes classification. Meta-analysis showed a pooled sensitivity of 0.631 (95% CI 0.450-0.782) and pooled specificity of 0.942 (95% CI 0.856-0.978) of LUS for ARDS diagnosis. In two studies, LUS could accurately differentiate between focal versus non-focal ARDS subphenotypes. Insufficient data was available to perform a meta-analysis.

CONCLUSION

This review confirms the hypothesis that LUS is a reliable method for diagnosing ARDS in adult patients. For the classification of focal or non-focal subphenotypes, LUS showed promising results, but more research is needed.

Respiratory support with standard low-flow oxygen therapy, high-flow oxygen therapy or continuous positive airway pressure in adults with acute hypoxaemic respiratory failure in a resource-limited setting: protocol for a randomised, open-label, clinical trial - the Acute Respiratory Intervention StudiEs in Africa (ARISE-AFRICA) study

RATIONALE

Acute hypoxaemic respiratory failure (AHRF) is associated with high mortality in sub-Saharan Africa. This is at least in part due to critical care-related resource constraints including limited access to invasive mechanical ventilation and/or highly skilled acute care workers. Continuous positive airway pressure (CPAP) and high-flow oxygen by nasal cannula (HFNC) may prove useful to reduce intubation, and therefore, improve survival outcomes among critically ill patients, particularly in resource-limited settings, but data in such settings are lacking. The aim of this study is to determine whether CPAP or HFNC as compared with standard oxygen therapy, could reduce mortality among adults presenting with AHRF in a resource-limited setting.

METHODS

This is a prospective, multicentre, randomised, controlled, stepped wedge trial, in which patients presenting with AHRF in Uganda will be randomly assigned to standard oxygen therapy delivered through a face mask, HFNC oxygen or CPAP. The primary outcome is all-cause mortality at 28 days. Secondary outcomes include the number of patients with criteria for intubation at day 7, the number of patients intubated at day 28, ventilator-free days at day 28 and tolerance of each respiratory support.

ETHICS AND DISSEMINATION

The study has obtained ethical approval from the Research and Ethics Committee, School of Biomedical Sciences, College of Health Sciences, Makerere University as well as the Uganda National Council for Science and Technology. Patients will be included after informed consent. The results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04693403.

PROTOCOL VERSION

8 September 2023; version 5.

Evaluation of a Lung Ultrasound Score in Hospitalized Adult Patients with COVID-19 in Barcelona, Spain

Background/Objectives: During the COVID-19 pandemic and the burden on hospital resources, the rapid categorization of high-risk COVID-19 patients became essential, and lung ultrasound (LUS) emerged as an alternative to chest computed tomography, offering speed, non-ionizing, repeatable, and bedside assessments. Various LUS score systems have been used, yet there is no consensus on an optimal severity cut-off. We assessed the performance of a 12-zone LUS score to identify adult COVID-19 patients with severe lung involvement using oxygen saturation (SpO2)/fractional inspired oxygen (FiO2) ratio as a reference standard to define the best cut-off for predicting adverse outcomes. Methods: We conducted a single-centre prospective study (August 2020-April 2021) at Hospital del Mar, Barcelona, Spain. Upon admission to the general ward or intensive care unit (ICU), clinicians performed LUS in adult patients with confirmed COVID-19 pneumonia. Severe lung involvement was defined as a SpO2/FiO2 ratio <315. The LUS score ranged from 0 to 36 based on the aeration patterns. Results: 248 patients were included. The admission LUS score showed moderate performance in identifying a SpO2/FiO2 ratio <315 (area under the ROC curve: 0.71; 95%CI 0.64-0.77). After adjustment for COVID-19 risk factors, an admission LUS score ≥17 was associated with an increased risk of in-hospital death (OR 5.31; 95%CI: 1.38-20.4), ICU admission (OR 3.50; 95%CI: 1.37-8.94) and need for IMV (OR 3.31; 95%CI: 1.19-9.13). Conclusions: Although the admission LUS score had limited performance in identifying severe lung involvement, a cut-off ≥17 score was associated with an increased risk of adverse outcomes. and could play a role in the rapid categorization of COVID-19 pneumonia patients, anticipating the need for advanced care.

Personalized mechanical ventilation guided by ultrasound in patients with acute respiratory distress syndrome (PEGASUS): study protocol for an international randomized clinical trial

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a frequent cause of hypoxemic respiratory failure with a mortality rate of approximately 30%. Identifying ARDS subphenotypes based on "focal" or "non-focal" lung morphology has the potential to better target mechanical ventilation strategies of individual patients. However, classifying morphology through chest radiography or computed tomography is either inaccurate or impractical. Lung ultrasound (LUS) is a non-invasive bedside tool that can accurately distinguish "focal" from "non-focal" lung morphology. We hypothesize that LUS-guided personalized mechanical ventilation in ARDS patients leads to a reduction in 90-day mortality compared to conventional mechanical ventilation.

METHODS

The Personalized Mechanical Ventilation Guided by UltraSound in Patients with Acute Respiratory Distress Syndrome (PEGASUS) study is an investigator-initiated, international, randomized clinical trial (RCT) that plans to enroll 538 invasively ventilated adult intensive care unit (ICU) patients with moderate to severe ARDS. Eligible patients will receive a LUS exam to classify lung morphology as "focal" or "non-focal". Thereafter, patients will be randomized within 12 h after ARDS diagnosis to receive standard care or personalized ventilation where the ventilation strategy is adjusted to the morphology subphenotype, i.e., higher positive end-expiratory pressure (PEEP) and recruitment maneuvers for "non-focal" ARDS and lower PEEP and prone positioning for "focal" ARDS. The primary endpoint is all-cause mortality at day 90. Secondary outcomes are mortality at day 28, ventilator-free days at day 28, ICU length of stay, ICU mortality, hospital length of stay, hospital mortality, and number of complications (ventilator-associated pneumonia, pneumothorax, and need for rescue therapy). After a pilot phase of 80 patients, the correct interpretation of LUS images and correct application of the intervention within the safe limits of mechanical ventilation will be evaluated.

DISCUSSION

PEGASUS is the first RCT that compares LUS-guided personalized mechanical ventilation with conventional ventilation in invasively ventilated patients with moderate and severe ARDS. If this study demonstrates that personalized ventilation guided by LUS can improve the outcomes of ARDS patients, it has the potential to shift the existing one-size-fits-all ventilation strategy towards a more individualized approach.

TRIAL REGISTRATION

The PEGASUS trial was registered before the inclusion of the first patient, https://clinicaltrials.gov/ (ID: NCT05492344).

Study on risk factors and treatment strategies of hypoxemia after acute type a aortic dissection surgery

Acute type A aortic dissection is a life-threatening cardiovascular disease characterized by rapid onset and high mortality. Emergency surgery is the preferred and reliable treatment option. However, postoperative complications significantly impact patient prognosis. Hypoxemia, a common complication, poses challenges in clinical treatment, negatively affecting patient outcomes and increasing the risk of mortality. Therefore, it is crucial to study and comprehend the risk factors and treatment strategies for hypoxemia following acute type A aortic dissection to facilitate early intervention.

Post-pandemic acute respiratory distress syndrome: A New Global Definition with extension to lower-resource regions

Acute respiratory distress syndrome (ARDS), first described in 1967, is characterized by acute respiratory failure causing profound hypoxemia, decreased pulmonary compliance, and bilateral CXR infiltrates. After several descriptions, the Berlin definition was adopted in 2012, which established three categories of severity according to hypoxemia (mild, moderate and severe), specified temporal aspects for diagnosis, and incorporated the use of non-invasive ventilation. The COVID-19 pandemic led to changes in ARDS management, focusing on continuous monitoring of oxygenation and on utilization of high-flow oxygen therapy and lung ultrasound. In 2021, a New Global Definition based on the Berlin definition of ARDS was proposed, which included a category for non-intubated patients, considered the use of SpO2, and established no particular requirement for oxygenation support in regions with limited resources. Although debates persist, the continuous evolution seeks to adapt to clinical and epidemiological needs, and to the search of personalized treatments.

Consensus statements on the utility of defining ARDS and the utility of past and current definitions of ARDS-protocol for a Delphi study

INTRODUCTION

Acute respiratory distress syndrome (ARDS), marked by acute hypoxemia and bilateral pulmonary infiltrates, has been defined in multiple ways since its first description. This Delphi study aims to collect global opinions on the conceptual framework of ARDS, assess the usefulness of components within current and past definitions and investigate the role of subphenotyping. The varied expertise of the panel will provide valuable insights for refining future ARDS definitions and improving clinical management.

METHODS

A diverse panel of 35-40 experts will be selected based on predefined criteria. Multiple choice questions (MCQs) or 7-point Likert-scale statements will be used in the iterative Delphi rounds to achieve consensus on key aspects related to the utility of definitions and subphenotyping. The Delphi rounds will be continued until a stable agreement or disagreement is achieved for all statements.

ANALYSIS

Consensus will be considered as reached when a choice in MCQs or Likert-scale statement achieved ≥80% of votes for agreement or disagreement. The stability will be checked by non-parametric χ2 tests or Kruskal Wallis test starting from the second round of Delphi process. A p-value ≥0.05 will be used to define stability.

ETHICS AND DISSEMINATION

The study will be conducted in full concordance with the principles of the Declaration of Helsinki and will be reported according to CREDES guidance. This study has been granted an ethical approval waiver by the NMC Healthcare Regional Research Ethics Committee, Dubai (NMCHC/CR/DXB/REC/APP/002), owing to the nature of the research. Informed consent will be obtained from all panellists before the start of the Delphi process. The study will be published in a peer-review journal with the authorship agreed as per ICMJE requirements.

TRIAL REGISTRATION NUMBER

NCT06159465.

Causes, outcomes and diagnosis of acute breathlessness hospital admissions in Malawi: protocol for a multicentre prospective cohort study

Background

Hospital admission due to breathlessness carries a significant burden to patients and healthcare systems, particularly impacting people in low-income countries. Prompt appropriate treatment is vital to improve outcomes, but this relies on accurate diagnostic tests which are of limited availability in resource-constrained settings. We will provide an accurate description of acute breathlessness presentations in a multicentre prospective cohort study in Malawi, a low resource setting in Southern Africa, and explore approaches to strengthen diagnostic capacity.

Objectives

Primary objective: Delineate between causes of breathlessness among adults admitted to hospital in Malawi and report disease prevalence. Secondary objectives : Determine patient outcomes, including mortality and hospital readmission 90 days after admission; determine the diagnostic accuracy of biomarkers to differentiate between heart failure and respiratory infections (such as pneumonia) including brain natriuretic peptides, procalcitonin and C-reactive protein.

Methods

This is a prospective longitudinal cohort study of adults (≥18 years) admitted to hospital with breathlessness across two hospitals: 1) Queen Elizabeth Central Hospital, Blantyre, Malawi; 2) Chiradzulu District Hospital, Chiradzulu, Malawi. Patients will be consecutively recruited within 24 hours of emergency presentation and followed-up until 90 days from hospital admission. We will conduct enhanced diagnostic tests with robust quality assurance and quality control to determine estimates of disease pathology. Diagnostic case definitions were selected following a systematic literature search.

Discussion

This study will provide detailed epidemiological description of adult hospital admissions due to breathlessness in low-income settings, which is currently poorly understood. We will delineate between causes using established case definitions and conduct nested diagnostic evaluation. The results have the potential to facilitate development of interventions targeted to strengthen diagnostic capacity, enable prompt and appropriate treatment, and ultimately improve both patient care and outcomes.

High-flow nasal oxygen therapy outside the intensive care unit

-

Acute Respiratory Distress Syndrome: Definition, Diagnosis, and Routine Management

Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung injury characterized by severe hypoxemic respiratory failure, bilateral opacities on chest imaging, and low lung compliance. ARDS is a heterogeneous syndrome that is the common end point of a wide variety of predisposing conditions, with complex pathophysiology and underlying mechanisms. Routine management of ARDS is centered on lung-protective ventilation strategies such as low tidal volume ventilation and targeting low airway pressures to avoid exacerbation of lung injury, as well as a conservative fluid management strategy.

Exploring the translational landscape of the long noncoding RNA transcriptome in acute respiratory distress syndrome: it is a long way to the top

Acute respiratory distress syndrome (ARDS) poses a significant and widespread public health challenge. Extensive research conducted in recent decades has considerably improved our understanding of the disease pathophysiology. Nevertheless, ARDS continues to rank among the leading causes of mortality in intensive care units and its management remains a formidable task, primarily due to its remarkable heterogeneity. As a consequence, the syndrome is underdiagnosed, prognostication has important gaps and selection of the appropriate therapeutic approach is laborious. In recent years, the noncoding transcriptome has emerged as a new area of attention for researchers interested in biomarker development. Numerous studies have confirmed the potential of long noncoding RNAs (lncRNAs), transcripts with little or no coding information, as noninvasive tools for diagnosis, prognosis and prediction of the therapeutic response across a broad spectrum of ailments, including respiratory conditions. This article aims to provide a comprehensive overview of lncRNAs with specific emphasis on their role as biomarkers. We review current knowledge on the circulating lncRNAs as potential markers that can be used to enhance decision making in ARDS management. Additionally, we address the primary limitations and outline the steps that will be essential for integration of the use of lncRNAs in clinical laboratories. Our ultimate objective is to provide a framework for the implementation of lncRNAs in the management of ARDS.

Endothelial and inflammatory pathophysiology in dengue shock: New insights from a prospective cohort study in Vietnam

Dengue shock (DS) is the most severe complication of dengue infection; endothelial hyperpermeability leads to profound plasma leakage, hypovolaemia and extravascular fluid accumulation. At present, the only treatment is supportive with intravenous fluid, but targeted endothelial stabilising therapies and host immune modulators are needed. With the aim of prioritising potential therapeutics, we conducted a prospective observational study of adults (≥16 years) with DS in Vietnam from 2019-2022, comparing the pathophysiology underlying circulatory failure with patients with septic shock (SS), and investigating the association of biomarkers with clinical severity (SOFA score, ICU admission, mortality) and pulmonary vascular leak (daily lung ultrasound for interstitial and pleural fluid). Plasma was collected at enrolment, 48 hours later and hospital discharge. We measured biomarkers of inflammation (IL-6, ferritin), endothelial activation (Ang-1, Ang-2, sTie-2, VCAM-1) and endothelial glycocalyx breakdown (hyaluronan, heparan sulfate, endocan, syndecan-1). We enrolled 135 patients with DS (median age 26, median SOFA score 7, 34 required ICU admission, 5 deaths), together with 37 patients with SS and 25 healthy controls. Within the DS group, IL-6 and ferritin were associated with admission SOFA score (IL-6: βeta0.70, p<0.001 & ferritin: βeta0.45, p<0.001), ICU admission (IL-6: OR 2.6, p<0.001 & ferritin: OR 1.55, p<0.001) and mortality (IL-6: OR 4.49, p = 0.005 & ferritin: OR 13.8, p = 0.02); both biomarkers discriminated survivors and non-survivors at 48 hours and all patients who died from DS had pre-mortem ferritin ≥100,000ng/ml. IL-6 most strongly correlated with severity of pulmonary vascular leakage (R = 0.41, p<0.001). Ang-2 correlated with pulmonary vascular leak (R = 0.33, p<0.001) and associated with SOFA score (β 0.81, p<0.001) and mortality (OR 8.06, p = 0.002). Ang-1 was associated with ICU admission (OR 1.6, p = 0.005) and mortality (OR 3.62, p = 0.006). All 4 glycocalyx biomarkers were positively associated with SOFA score, but only syndecan-1 was associated with ICU admission (OR 2.02, p<0.001) and mortality (OR 6.51, p<0.001). This study highlights the central role of hyperinflammation in determining outcomes from DS; the data suggest that anti-IL-1 and anti-IL-6 immune modulators and Tie2 agonists may be considered as candidates for therapeutic trials in severe dengue.

Approach towards surveillance-based diagnosis of acute respiratory illness in India: Expert recommendations

BACKGROUND

Emerging infectious diseases, often zoonotic, demand a collaborative "One-Health" surveillance approach due to human activities. The need for standardized diagnostic and surveillance algorithms is emphasized to address the difficulty in clinical differentiation and curb antimicrobial resistance.

OBJECTIVE

The present recommendations are comprehensive diagnostic and surveillance algorithm for ARIs, developed by the Indian Council of Medical Research (ICMR), which aims to enhance early detection and treatment with improved surveillance. This algorithm shall be serving as a blueprint for respiratory infections landscape in the country and early detection of surge of respiratory infections in the country.

CONTENT

The ICMR has risen up to the threat of emerging and re-emerging infections. Here, we seek to recommend a structured approach for diagnosing respiratory illnesses. The recommendations emphasize the significance of prioritizing respiratory pathogens based on factors such as the frequency of occurrence (seasonal or geographical), disease severity, ease of diagnosis and public health importance. The proposed surveillance-based diagnostic algorithm for ARI relies on a combination of gold-standard conventional methods, innovative serological and molecular techniques, as well as radiological approaches, which collectively contribute to the detection of various causative agents. The diagnostic part of the integrated algorithm can be dealt at the local microbiology laboratory of the healthcare facility with the few positive and negative specimens shipped to linked viral disease research laboratories (VRDLs) and other ICMR designated laboratories for genome characterisation, cluster identification and identification of novel agents.

A Game Changer for ARDS? Unraveling the Potential of the SF Ratio

Rangappa R. A Game Changer for ARDS? Unraveling the Potential of the SF Ratio. Indian J Crit Care Med 2024;28(3):191-192.

Investigational pharmacological agents for the treatment of ARDS

INTRODUCTION

Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous form of lung injury with severe hypoxemia and bilateral infiltrates after an inciting event that results in diffuse lung inflammation with a high mortality rate. While research in COVID-related ARDS has resulted in several pharmacotherapeutic agents that have undergone successful investigation, non-COVID ARDS studies have not resulted in many widely accepted pharmacotherapeutic agents despite exhaustive research.

AREAS COVERED

The aim of this review is to discuss adjuvant pharmacotherapies targeting non-COVID Acute Lung Injury (ALI)/ARDS and novel therapeutics in COVID associated ALI/ARDS. In ARDS, variable data may support selective use of neuromuscular blocking agents, corticosteroids and neutrophil elastase inhibitors, but are not yet universally used. COVID-ALI/ARDS has data supporting the use of IL-6 monoclonal antibodies, corticosteroids, and JAK inhibitor therapy.

EXPERT OPINION

Although ALI/ARDS modifying pharmacological agents have been identified in COVID-related disease, the data in non-COVID ALI/ARDS has been less compelling. The increased use of more specific molecular phenotyping based on physiologic parameters and biomarkers, will ensure equipoise between groups, and will likely allow more precision in confirming pharmacological agent efficacy in future studies.

A Prospective Observational Study Comparing Oxygen Saturation/Fraction of Inspired Oxygen Ratio with Partial Pressure of Oxygen in Arterial Blood/Fraction of Inspired Oxygen Ratio among Critically Ill Patients Requiring Different Modes of Oxygen Supplementation in Intensive Care Unit

Background

Intensive care unit (ICU) patients face a significant rise in mortality rates due to acute hypoxemic respiratory failure (AHRF). The diagnosis of AHRF is based on the PF ratio, but it has limitations in resource-constrained settings. Instead, the Kigali modification suggests using the oxygen saturation/fraction of inspired oxygen (SF) ratio. This study aims to correlate SF ratio and arterial oxygen pressure (PF) ratio in critically ill adults with hypoxemic respiratory failure, who required O2 therapy through different modes of oxygen supplementation.

Materials and methods

In an ICU, a prospective observational study included 125 adult AHRF patients receiving oxygen therapy, with data collected on FiO2, PaO2, and SpO2. The SF ratio and PF ratio were calculated, and their correlation was assessed using statistical analysis. The receiver operator characteristics (ROC) curve analysis was conducted to assess the diagnostic precision of the SF ratio in identifying AHRF.

Results

Data from a total of 250 samples were collected. The study showed a positive correlation (r = 0.622) between the SF ratio and the PF ratio. The SF threshold values of 252 and 321 were established for PF values of 200 and 300, respectively, featuring a sensitivity of 69% and specificity of 95%. Furthermore, it is worth noting that the PF ratio and SF ratio are interchangeable, regardless of the type of oxygen therapy, as the median values of both the PF ratio and SF ratio displayed statistical significance (p < 0.01) in both acidosis and alkalosis conditions.

Conclusion

For patients with AHRF, the noninvasive SF ratio can effectively serve as a substitute for the invasive PF ratio across all oxygen supplementation modes.

How to cite this article

Alur TR, Iyer SS, Shah JN, Kulkarni S, Jedge P, Patil V. A Prospective Observational Study Comparing Oxygen Saturation/Fraction of Inspired Oxygen Ratio with Partial Pressure of Oxygen in Arterial Blood/Fraction of Inspired Oxygen Ratio among Critically Ill Patients Requiring Different Modes of Oxygen Supplementation in Intensive Care Unit. Indian J Crit Care Med 2024; 28(3):251-255.

Use of Lung Ultrasound in the New Definitions of Acute Respiratory Distress Syndrome Increases the Occurrence Rate of Acute Respiratory Distress Syndrome

OBJECTIVES

To assess the effect of incorporating bilateral abnormalities as detected by lung ultrasound (LUS) in the Kigali modification and the New Global definition of acute respiratory distress syndrome (ARDS) on the occurrence rate of ARDS.

DESIGN

Post hoc analysis of a previously published prospective cohort study.

SETTING

An academic mixed medical-surgical ICU.

PATIENTS

The original study included critically ill adults with any opacity on chest radiography in whom subsequent LUS was performed. Patients with ARDS according to the Berlin definition, COVID-19 patients and patients with major thorax trauma were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

LUS was performed within 24 hours of chest radiography and the presence of unilateral and bilateral abnormalities on LUS and chest radiograph (opacities) was scored. Subsequently, the Kigali modification and the New Global definition of ARDS were applied by two independent researchers on the patients with newly found bilateral opacities. Of 120 patients, 116 were included in this post hoc analysis. Thirty-three patients had bilateral opacities on LUS and unilateral opacities on chest radiograph. Fourteen of these patients had ARDS according to the Kigali modification and 12 had ARDS according to the New Global definition. The detected LUS patterns were significantly different between patients with and without ARDS ( p = 0.004). An A-profile with a positive PosteroLateral Alveolar and/or Pleural Syndrome was most prevalent in patients without ARDS, whereas heterogeneous and mixed A, B, and C patterns were most prevalent in patients with ARDS.

CONCLUSION

The addition of bilateral abnormalities as detected by LUS to the Kigali modification and the New Global definition increases the occurrence rate of the ARDS. The nomenclature for LUS needs to be better defined as LUS patterns differ between patients with and without ARDS. Incorporating well-defined LUS criteria can increase specificity and sensitivity of new ARDS definitions.

Incidence and Outcomes of Acute Respiratory Distress Syndrome in Brain-Injured Patients Receiving Invasive Ventilation: A Secondary Analysis of the ENIO Study

Background: Acute respiratory distress syndrome (ARDS) is an important pulmonary complication in brain-injured patients receiving invasive mechanical ventilation (IMV). We aimed to evaluate the incidence and association between ARDS and clinical outcomes in patients with different forms of acute brain injury requiring IMV in the intensive care unit (ICU). Methods: This was a preplanned secondary analysis of a prospective, multicenter, international cohort study (NCT03400904). We included brain-injured patients receiving IMV for ≥ 24 h. ARDS was the main exposure of interest and was identified during index ICU admission using the Berlin definition. We examined the incidence and adjusted association of ARDS with ICU mortality, ICU length of stay, duration of IMV, and extubation failure. Outcomes were evaluated using mixed-effect logistic regression and cause-specific Cox proportional hazards models. Results: 1492 patients from 67 hospitals and 16 countries were included in the analysis, of whom 137 individuals developed ARDS (9.2% of overall cohort). Across countries, the median ARDS incidence was 5.1% (interquartile range [IQR] 0-10; range 0-27.3). ARDS was associated with increased ICU mortality (adjusted odds ratio (OR) 2.66; 95% confidence interval [CI], 1.29-5.48), longer ICU length of stay (adjusted hazard ratio [HR] 0.59; 95% CI, 0.48-0.73), and longer duration of IMV (adjusted HR 0.54; 95% CI, 0.44-0.67). The association between ARDS and extubation failure approached statistical significance (adjusted HR 1.48; 95% CI 0.99-2.21). Higher ARDS severity was associated with incrementally longer ICU length of stay and longer cumulative duration of IMV. Findings remained robust in a sensitivity analysis evaluating the magnitude of unmeasured confounding. Conclusions: In this cohort of acutely brain-injured patients, the incidence of ARDS was similar to that reported in other mixed cohorts of critically ill patients. Development of ARDS was associated with worse outcomes.