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

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.

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).

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.

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

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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.

The Predictive Validity of the Berlin Definition of Acute Respiratory Distress Syndrome for Patients With COVID-19-Related Respiratory Failure Treated With High-Flow Nasal Oxygen: A Multicenter, Prospective Cohort Study

OBJECTIVES

The Berlin definition of acute respiratory distress syndrome (ARDS) was constructed for patients receiving invasive mechanical ventilation (IMV) with consideration given to issues related to reliability, feasibility, and validity. Notwithstanding, patients with acute respiratory failure (ARF) may be treated with high-flow nasal oxygen (HFNO) and may not fall within the scope of the original definition. We aimed to evaluate the predictive validity of the Berlin definition in HFNO-treated patients with COVID-19-related respiratory failure who otherwise met ARDS criteria.

DESIGN

Multicenter, prospective cohort study.

SETTING

Five ICUs of five centers in Argentina from March 2020 to September 2021.

PATIENTS

We consecutively included HFNO-treated patients older than 18 years with confirmed COVID-19-related ARF, a Pa o2 /F io2 of less than 300 mm Hg, bilateral infiltrates on imaging, and worsening respiratory symptoms for less than 1 week.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We evaluated the predictive validity of mortality at day 28 using the area under the receiver operating characteristics curve (AUC), compared the predictive validity across subgroups, and characterized relevant clinical outcomes. We screened 1,231 patients and included 696 ARDS patients [30 (4%) mild, 380 (55%) moderate, and 286 (41%) severe]. For the study cohort, the AUC for mortality at day 28 was 0.606 (95% CI, 0.561-0.651) with the AUC for subgroups being similar to that of the overall cohort. Two hundred fifty-six patients (37%) received IMV. By day 28, 142 patients (21%) had died, of whom 81 (57%) had severe ARDS. Mortality occurred primarily in patients who were transitioned to IMV.

CONCLUSIONS

The predictive validity of the Berlin ARDS definition was similar for HFNO-treated patients as compared with the original population of invasively ventilated patients. Our findings support the extension of the Berlin definition to HFNO-treated patients with ARDS.

A New Global Definition of Acute Respiratory Distress Syndrome

Background: Since publication of the 2012 Berlin definition of acute respiratory distress syndrome (ARDS), several developments have supported the need for an expansion of the definition, including the use of high-flow nasal oxygen, the expansion of the use of pulse oximetry in place of arterial blood gases, the use of ultrasound for chest imaging, and the need for applicability in resource-limited settings. Methods: A consensus conference of 32 critical care ARDS experts was convened, had six virtual meetings (June 2021 to March 2022), and subsequently obtained input from members of several critical care societies. The goal was to develop a definition that would 1) identify patients with the currently accepted conceptual framework for ARDS, 2) facilitate rapid ARDS diagnosis for clinical care and research, 3) be applicable in resource-limited settings, 4) be useful for testing specific therapies, and 5) be practical for communication to patients and caregivers. Results: The committee made four main recommendations: 1) include high-flow nasal oxygen with a minimum flow rate of ⩾30 L/min; 2) use PaO2:FiO2 ⩽ 300 mm Hg or oxygen saturation as measured by pulse oximetry SpO2:FiO2 ⩽ 315 (if oxygen saturation as measured by pulse oximetry is ⩽97%) to identify hypoxemia; 3) retain bilateral opacities for imaging criteria but add ultrasound as an imaging modality, especially in resource-limited areas; and 4) in resource-limited settings, do not require positive end-expiratory pressure, oxygen flow rate, or specific respiratory support devices. Conclusions: We propose a new global definition of ARDS that builds on the Berlin definition. The recommendations also identify areas for future research, including the need for prospective assessments of the feasibility, reliability, and prognostic validity of the proposed global definition.

Categorizing Acute Respiratory Distress Syndrome with Different Severities by Oxygen Saturation Index

The oxygen saturation index (OSI), defined by FIO2/SpO2 multiplied by the mean airway pressure, has been reported to exceed the Berlin definition in predicting the mortality of acute respiratory distress syndrome (ARDS). The OSI has served as an alternative to the Berlin definition in categorizing pediatric ARDS. However, the use of the OSI for the stratification of adult ARDS has not been reported. A total of 379 invasively ventilated adult ARDS patients were retrospectively studied. The ARDS patients were classified into three groups by their incidence rate of mortality: mild (OSI < 14.69), moderate (14.69 < OSI < 23.08) and severe (OSI > 23.08). OSI-based categorization was highly correlated with the Berlin definition by a Kendall's tau of 0.578 (p < 0.001). The Kaplan-Meier curves of the three OSI-based groups were significantly different (p < 0.001). By the Berlin definition, the hazard ratio for 28-day mortality was 0.58 (0.33-1.05) and 0.95 (0.55-1.67) for the moderate and severe groups, respectively (compared to the mild group). In contrast, the corresponding hazard ratio was 1.01 (0.69-1.47) and 2.39 (1.71-3.35) for the moderate and severe groups defined by the OSI. By multivariate analysis, OSI-based severe ARDS was independently associated with 28-D or 90-D mortality. In conclusion, we report the first OSI-based stratification for adult ARDS and find that it serves well as an alternative to the Berlin definition.

Immunological and biochemical biomarker alterations among SARS-COV-2 patients with varying disease phenotypes in Uganda

Every novel infection requires an assessment of the host response coupled with identification of unique biomarkers for predicting disease pathogenesis, treatment targets and diagnostic utility. Studies have exposed dysregulated inflammatory response induced by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as significant predictor or cause of disease severity/prognosis and death. This study evaluated inflammatory biomarkers induced by SARS-CoV-2 in plasma of patients with varying disease phenotypes and healthy controls with prognostic or therapeutic potential. We stratified SARS-CoV-2 plasma samples based on disease status (asymptomatic, mild, severe, and healthy controls), as diagnosed by RT-PCR SARS-CoV-2. We used a solid phase sandwich and competitive Enzyme-Linked Immunosorbent Assay (ELISA) to measure levels of panels of immunological (IFN-γ, TNF-α, IL-6, and IL-10) and biochemical markers (Ferritin, Procalcitonin, C-Reactive Protein, Angiotensin II, Homocysteine, and D-dimer). Biomarker levels were compared across SARS-CoV-2 disease stratification. Plasma IFN-γ, TNF-α, IL-6, and IL-10 levels were significantly (P < 0.05) elevated in the severe SARS-CoV-2 patients as compared to mild, asymptomatic, and healthy controls. Ferritin, Homocysteine, and D-dimer plasma levels were significantly elevated in severe cases over asymptomatic and healthy controls. Plasma C-reactive protein and Angiotensin II levels were significantly (P < 0.05) higher in mild than severe cases and healthy controls. Plasma Procalcitonin levels were significantly higher in asymptomatic than in mild, severe cases and healthy controls. Our study demonstrates the role of host inflammatory biomarkers in modulating the pathogenesis of COVID-19. The study proposes a number of potential biomarkers that could be explored as SARS-CoV-2 treatment targets and possible prognostic predictors for a severe outcome. The comprehensive analysis of prognostic biomarkers may contribute to the evidence-based management of COVID-19 patients.

Ventilatory Management of Patients with Acute Respiratory Distress Syndrome Due to SARS-CoV-2

The emergence of the new SARS-CoV-2 in December 2019 caused a worldwide pandemic of the resultant disease, COVID-19. There was a massive surge in admissions to intensive care units (ICU), notably of patients with hypoxaemic acute respiratory failure. In these patients, optimal oxygen therapy was crucial. In this article, we discuss tracheal intubation to provide mechanical ventilation in patients with hypoxaemic acute respiratory failure due to SARS-CoV-2. We first describe the pathophysiology of respiratory anomalies leading to acute respiratory distress syndrome (ARDS) due to infection with SARS-CoV-2, and then briefly review management, focusing particularly on the ventilation strategy. Overall, the ventilatory management of ARDS due to SARS-CoV-2 infection is largely the same as that applied in ARDS from other causes, and lung-protective ventilation is recommended. The difference lies in the initial clinical presentation, with profound hypoxaemia often observed concomitantly with near-normal pulmonary compliance.

Iron accumulation drives fibrosis, senescence and the senescence-associated secretory phenotype

Fibrogenesis is part of a normal protective response to tissue injury that can become irreversible and progressive, leading to fatal diseases. Senescent cells are a main driver of fibrotic diseases through their secretome, known as senescence-associated secretory phenotype (SASP). Here, we report that cellular senescence, and multiple types of fibrotic diseases in mice and humans are characterized by the accumulation of iron. We show that vascular and hemolytic injuries are efficient in triggering iron accumulation, which in turn can cause senescence and promote fibrosis. Notably, we find that senescent cells persistently accumulate iron, even when the surge of extracellular iron has subdued. Indeed, under normal conditions of extracellular iron, cells exposed to different types of senescence-inducing insults accumulate abundant ferritin-bound iron, mostly within lysosomes, and present high levels of labile iron, which fuels the generation of reactive oxygen species and the SASP. Finally, we demonstrate that detection of iron by magnetic resonance imaging might allow non-invasive assessment of fibrotic burden in the kidneys of mice and in patients with renal fibrosis. Our findings suggest that iron accumulation plays a central role in senescence and fibrosis, even when the initiating events may be independent of iron, and identify iron metabolism as a potential therapeutic target for senescence-associated diseases.

Functional recovery in a cohort of ECMO and non-ECMO acute respiratory distress syndrome survivors

BACKGROUND

The mortality benefit of VV-ECMO in ARDS has been extensively studied, but the impact on long-term functional outcomes of survivors is poorly defined. We aimed to assess the association between ECMO and functional outcomes in a contemporaneous cohort of survivors of ARDS.

METHODS

Multicenter retrospective cohort study of ARDS survivors who presented to follow-up clinic. The primary outcome was FVC% predicted. Univariate and multivariate regression models were used to evaluate the impact of ECMO on the primary outcome.

RESULTS

This study enrolled 110 survivors of ARDS, 34 of whom were managed using ECMO. The ECMO cohort was younger (35 [28, 50] vs. 51 [44, 61] years old, p < 0.01), less likely to have COVID-19 (58% vs. 96%, p < 0.01), more severely ill based on the Sequential Organ Failure Assessment (SOFA) score (7 [5, 9] vs. 4 [3, 6], p < 0.01), dynamic lung compliance (15 mL/cmH20 [11, 20] vs. 27 mL/cmH20 [23, 35], p < 0.01), oxygenation index (26 [22, 33] vs. 9 [6, 11], p < 0.01), and their need for rescue modes of ventilation. ECMO patients had significantly longer lengths of hospitalization (46 [27, 62] vs. 16 [12, 31] days, p < 0.01) ICU stay (29 [19, 43] vs. 10 [5, 17] days, p < 0.01), and duration of mechanical ventilation (24 [14, 42] vs. 10 [7, 17] days, p < 0.01). Functional outcomes were similar in ECMO and non-ECMO patients. ECMO did not predict changes in lung function when adjusting for age, SOFA, COVID-19 status, or length of hospitalization.

CONCLUSIONS

There were no significant differences in the FVC% predicted, or other markers of pulmonary, neurocognitive, or psychiatric functional recovery outcomes, when comparing a contemporaneous clinic-based cohort of survivors of ARDS managed with ECMO to those without ECMO.

Noninvasive Oxygenation Indices: New Tools for Resource-limited Settings?

How to cite this article: Jagiasi BG. Noninvasive Oxygenation Indices: New Tools for Resource-limited Settings? Indian J Crit Care Med 2023;27(11):784-785.

Prediction model for in-hospital mortality in patients at high altitudes with ARDS due to COVID-19

INTRODUCTION

The diagnosis of acute respiratory distress syndrome (ARDS) includes the ratio of pressure arterial oxygen and inspired oxygen fraction (P/F) ≤ 300, which is often adjusted in locations more than 1,000 meters above sea level (masl) due to hypobaric hypoxemia. The main objective of this study was to develop a prediction model for in-hospital mortality among patients with ARDS due to coronavirus disease 2019 (COVID-19) (C-ARDS) at 2,600 masl with easily available variables at patient admission and to compare its discrimination capacity with a second model using the P/F adjusted for this high altitude.

METHODS

This study was an analysis of data from patients with C-ARDS treated between March 2020 and July 2021 in a university hospital located in the city of Bogotá, Colombia, at 2,600 masl. Demographic and laboratory data were extracted from electronic records. For the prediction model, univariate analyses were performed to screen variables with p <0.25. Then, these variables were automatically selected with a backward stepwise approach with a significance level of 0.1. The interaction terms and fractional polynomials were also examined in the final model. Multiple imputation procedures and bootstraps were used to obtain the coefficients with the best external validation. In addition, total adjustment of the model and logistic regression diagnostics were performed. The same methodology was used to develop a second model with the P/F adjusted for altitude. Finally, the areas under the curve (AUCs) of the receiver operating characteristic (ROC) curves of the two models were compared.

RESULTS

A total of 2,210 subjects were included in the final analysis. The final model included 11 variables without interaction terms or nonlinear functions. The coefficients are presented excluding influential observations. The final equation for the model fit was g(x) = age(0.04819)+weight(0.00653)+height(-0.01856)+haemoglobin(-0.0916)+platelet count(-0.003614)+ creatinine(0.0958)+lactate dehydrogenase(0.001589)+sodium(-0.02298)+potassium(0.1574)+systolic pressure(-0.00308)+if moderate ARDS(0.628)+if severe ARDS(1.379), and the probability of in-hospital death was p (x) = e g (x)/(1+ e g (x)). The AUC of the ROC curve was 0.7601 (95% confidence interval (CI) 0.74-0, 78). The second model with the adjusted P/F presented an AUC of 0.754 (95% CI 0.73-0.77). No statistically significant difference was found between the AUC curves (p value = 0.6795).

CONCLUSION

This study presents a prediction model for patients with C-ARDS at 2,600 masl with easily available admission variables for early stratification of in-hospital mortality risk. Adjusting the P/F for 2,600 masl did not improve the predictive capacity of the model. We do not recommend adjusting the P/F for altitude.

The diagnostic accuracy of lung ultrasound to determine PiCCO-derived extravascular lung water in invasively ventilated patients with COVID-19 ARDS

BACKGROUND

Lung ultrasound (LUS) can detect pulmonary edema and it is under consideration to be added to updated acute respiratory distress syndrome (ARDS) criteria. However, it remains uncertain whether different LUS scores can be used to quantify pulmonary edema in patient with ARDS.

OBJECTIVES

This study examined the diagnostic accuracy of four LUS scores with the extravascular lung water index (EVLWi) assessed by transpulmonary thermodilution in patients with moderate-to-severe COVID-19 ARDS.

METHODS

In this predefined secondary analysis of a multicenter randomized-controlled trial (InventCOVID), patients were enrolled within 48 hours after intubation and underwent LUS and EVLWi measurement on the first and fourth day after enrolment. EVLWi and ∆EVLWi were used as reference standards. Two 12-region scores (global LUS and LUS-ARDS), an 8-region anterior-lateral score and a 4-region B-line score were used as index tests. Pearson correlation was performed and the area under the receiver operating characteristics curve (AUROCC) for severe pulmonary edema (EVLWi > 15 mL/kg) was calculated.

RESULTS

26 out of 30 patients (87%) had complete LUS and EVLWi measurements at time point 1 and 24 out of 29 patients (83%) at time point 2. The global LUS (r = 0.54), LUS-ARDS (r = 0.58) and anterior-lateral score (r = 0.54) correlated significantly with EVLWi, while the B-line score did not (r = 0.32). ∆global LUS (r = 0.49) and ∆anterior-lateral LUS (r = 0.52) correlated significantly with ∆EVLWi. AUROCC for EVLWi > 15 ml/kg was 0.73 for the global LUS, 0.79 for the anterior-lateral and 0.85 for the LUS-ARDS score.

CONCLUSIONS

Overall, LUS demonstrated an acceptable diagnostic accuracy for detection of pulmonary edema in moderate-to-severe COVID-19 ARDS when compared with PICCO. For identifying patients at risk of severe pulmonary edema, an extended score considering pleural morphology may be of added value.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04794088, registered on 11 March 2021. European Clinical Trials Database number 2020-005447-23.

Arterial Blood Gas Analysis: A New Look at the Old Formula

How to cite this article: Todi S. Arterial Blood Gas Analysis: A New Look at the Old Formula. Indian J Crit Care Med 2023;27(10):699-700.

Estimating the attributable fraction of mortality from acute respiratory distress syndrome to inform enrichment in future randomised clinical trials

BACKGROUND

Efficiency of randomised clinical trials of acute respiratory distress syndrome (ARDS) depends on the fraction of deaths attributable to ARDS (AFARDS) to which interventions are targeted. Estimates of AFARDS in subpopulations of ARDS could improve design of ARDS trials.

METHODS

We performed a matched case-control study using the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE cohort. Primary outcome was intensive care unit mortality. We used nearest neighbour propensity score matching without replacement to match ARDS to non-ARDS populations. We derived two separate AFARDS estimates by matching patients with ARDS to patients with non-acute hypoxaemic respiratory failure (non-AHRF) and to patients with AHRF with unilateral infiltrates only (AHRF-UL). We also estimated AFARDS in subgroups based on severity of hypoxaemia, number of lung quadrants involved and hyperinflammatory versus hypoinflammatory phenotypes. Additionally, we derived AFAHRF estimates by matching patients with AHRF to non-AHRF controls, and AFAHRF-UL estimates by matching patients with AHRF-UL to non-AHRF controls.

RESULTS

Estimated AFARDS was 20.9% (95% CI 10.5% to 31.4%) when compared with AHRF-UL controls and 38.0% (95% CI 34.4% to 41.6%) compared with non-AHRF controls. Within subgroups, estimates for AFARDS compared with AHRF-UL controls were highest in patients with severe hypoxaemia (41.1% (95% CI 25.2% to 57.1%)), in those with four quadrant involvement on chest radiography (28.9% (95% CI 13.4% to 44.3%)) and in the hyperinflammatory subphenotype (26.8% (95% CI 6.9% to 46.7%)). Estimated AFAHRF was 33.8% (95% CI 30.5% to 37.1%) compared with non-AHRF controls. Estimated AFAHRF-UL was 21.3% (95% CI 312.8% to 29.7%) compared with non-AHRF controls.

CONCLUSIONS

Overall AFARDS mean values were between 20.9% and 38.0%, with higher AFARDS seen with severe hypoxaemia, four quadrant involvement on chest radiography and hyperinflammatory ARDS.

The role of IL-6, ferritin, and coagulopathy in Covid-19 clinical progression

Background In COVID-19, the release of pro-inflammatory mediators in the cytokine storm, primarily interleukin-6 (IL-6), has been hypothesized to induce pulmonary intravascular coagulation. However, the relationship between IL-6 and coagulopathy remains unclear in COVID-19 progression. We aimed to investigate the correlation of IL-6 with D-dimer, fibrinogen, prothrombin time (PT), and ferritin. Furthermore, we also analyzed the effect of those parameters on the worsening of COVID-19 patients. Methods A prospective cohort study was conducted in moderate and severe COVID-19 patients from June 2020 to January 2021. A serial evaluation of IL-6, D-dimer, fibrinogen, ferritin, and PT was performed and correlated with the patient's condition at admission and on the 14th day. The outcomes (improvement, worsening, or discharged patients) were recorded during the study. Results Of 374 patients, 73 study subjects (61 severe and 12 moderate COVID-19) were included in this study. A total of 35 out of 61 severe and one out of 12 moderate illness subjects had experienced worsening. Spearman-rank correlation of IL-6 with with ferritin, D-dimer, fibrinogen, and PT was 0.08 ( p=0.5), -0.13 ( p=0.27), 0.01 ( p=0.91), and 0.03 ( p=0.77), respectively. In ROC analysis, D-dimer (74,77%) and IL-6 (71,32%) were the highest among other variables (>60%). Conclusions In COVID-19 patients, there was a correlation between elevated IL-6 and D-dimer levels with disease deterioration. There was no correlation between elevated IL-6 levels with ferritin, D-dimer, fibrinogen, and PT levels. Therefore, changes in IL-6 and D-dimer can predict worsening in moderate and severe COVID-19 patients.