Functional chest imaging using electrical impedance tomography (EIT) has experienced an impressive technological development since its invention in the early eighties of the last century. The number of experimental and clinical studies using this technology is continuously rising, and the increasing availability of devices approved for clinical use accelerates and diversifies its applications in patients. EIT is predominantly used in intensive care units but its utilisation in operating theatres, delivery rooms, pulmonary function laboratories and even remote outpatient settings is growing. Chest EIT is mainly applied to determine the regional distribution of pulmonary ventilation, aeration changes, and respiratory system mechanics both during mechanical ventilation and spontaneous breathing, but an increase in the use of chest EIT for imaging lung perfusion and cardiac action has recently been noted. The ongoing innovation of both EIT hardware and software, the new application fields, and the rising number of users of this technology require consensus on EIT terminology and definitions. This secures a common framework for conducting EIT studies, patient examinations and guarantees unified analysis of EIT data, documentation, reporting and comparability of findings. Our article provides a comprehensive consensus document on EIT terminology and definitions generated by EIT experts of the international TRanslational EIT development stuDy group in cooperation with the producers of EIT technology. It not only updates and extends the first consensus EIT terminology published in 2017, but also offers a new taxonomy of EIT measures, systematically based on the quantification of ventilation-related, heartbeat-related, and contrast-enhanced EIT signals. Thanks to its clear structure with tabulated recommended EIT terms, abbreviations, comprehensible explanations, notes, extensive literature sources and parameter calculations, EIT researchers, clinical users and manufacturers may use this document as a reference source of information relevant for chest EIT.

The ventilatory ratio (VR) is frequently used as a surrogate marker of ventilatory efficiency in patients with ARDS. However, its ability to reflect changes in alveolar ventilation (V̇Talv/VT) when respiratory mechanics are modified remains unknown. This study aimed to evaluate the relationship between VR and V̇Talv/VT during sequential changes in respiratory mechanics=, tidal volume (VT), and minute ventilation (V̇E) in patients with ARDS. This was a secondary analysis of a quasi-experimental, repeated-measures study conducted in a single-center adult ICU. Twenty-two patients with ARDS were evaluated across three sequential 60 min controlled periods, during which trunk inclination was adjusted to induce changes in VT. At the end of each period, VR was calculated, and V̇Talv/VT was measured using volumetric capnography. A total of 66 paired measurements were analyzed in this study. By design, VT increased from Time 1 to Time 2 by + 62 mL and decreased from Time 2 to Time 3 by − 68 mL. These changes in VT were associated with the following: VR was not significantly different between Time 1 and Time 2 [− 0.23 (95

PURPOSE OF REVIEW:Acute respiratory failure is a frequent cause of ICU admission and carries a high mortality rate. Multimodal respiratory monitoring integrating imaging techniques, respiratory mechanics and functional data provides a more comprehensive physiologically grounded assessment of the respiratory status. This review describes recent advances in noninvasive bedside monitoring options that when combined could enable a safer, more personalized management of patients on invasive mechanical ventilation. RECENT FINDINGS:Quantitative lung ultrasound can be reliably used at the bedside to quantify and monitor the lung density and guide the ventilatory strategy; a recent expert consensus has defined its technical and clinical applications. While providing information on lung morphology, it needs to be combined with other bedside tools such as tidal hysteresis in pressure-volume loops and/or EIT to individualize ventilatory settings. Muscle ultrasound assessment is used to monitor active patients, mainly to quantify patient effort and predict weaning outcomes. Expired CO 2 kinetics evaluates lung efficiency, with important prognostic implications, and new promising developments may allow to continuously estimate static lung volume and cardiac output. SUMMARY:Multiple noninvasive bedside tools are available for a multimodal assessment of the respiratory system; while each evaluates the patient from a different perspective, their effectiveness is maximized when they are integrated and combined for daily monitoring and clinical assessment.

Objective.The composition of alveolar gases is based on theoretical assumptions. The role of expired samples at the airway opening in representing the true value of mean alveolar gas remains a subject of debate. We hypothesized that phase III of oxygrams and capnograms obtained at the airway opening must be qualitative similar to the one found at the lung acini. The aim of this study is to test this hypothesis, analyzing the phase III of breath-by-breath samples of airway and alveolar gases from mechanically ventilated patients.Approach.The study compared expired gases at the airway opening and direct gas samples taken from peripheral lung parenchyma in ventilated patients undergoing thoracic surgery. We used video-assisted lobectomies as a model to get direct alveolar gas samples from the lobe that was removed by surgery.Main results.In ten anesthetized patients before lobectomy, the corresponding lung lobe was punctured by a 20 G angiocath at ∼5 mm of depth and then connected via a sampling line to sidestream and mainstream capnographs. An oscillating pattern in synchrony with the mechanical breath cycles was observed in the alveolar CO2and O2samples. The alveolar capnograms and oxygrams revealed an absence of phase I, very short phase II, and a similar phase III. The slope of phase III of the expired curves at the airway opening [median 2.20 (inter-quartile range 1.28) mmHg s-1] were similar to the one of the alveolar mainstream capnograms [median 2.18 (inter-quartile range 1.24) mmHg s-1;p= 0.76].Significance.Our findings suggest that alveolar gas can be reliably sampled at the airway opening. The similarity in the slopes of phase III between airway and alveolar samples highlights the significance of continuous gas diffusion through the alveolar-capillary membrane as well as the presence of convection- and diffusion-dependent inhomogeneities in their origin.

We aimed to test a new method to determine the positive-end expiratory pressure (PEEP) that maintains the lungs open after a recruitment maneuver (RM). In eleven anesthetized patients, we compared the standard RM searching for the optimal PEEP based on the highest respiratory compliance (PEEPCrs), with a new method. This method performs a RM during a slow pressure-volume curve and detects the optimal PEEP using the novel barometric capnography curve (BCap); i.e. the plot of expired carbon dioxide versus airway pressure. The lungs’ closing pressure was detected when the slope of phase III of the BCap changed along this slow expiration (PEEPBCap). The main objective was to compare PEEPBCap with the reference PEEPCrs. As a secondary objective, we explored the association between PEEPBCap and the polarity change in end-expiratory transpulmonary pressure (PEEPPL) during the deflation phase of a slow flow PV curve. We found a PEEPBCap of 8.5(3.3) cmH2O that was no statistically different from the PEEPCrs of 10.0(4.0) cmH2O (p = 0.72). Both methods correlated well with a Rho of 0.84 (p < 0.001). The Bland-Altman plot showed a bias of 0.19 and LOA of 1.92 cmH2O (95

Rationale: The optimal strategy to prevent reintubation in patients with obesity remains uncertain. Objectives: We aimed to determine whether noninvasive ventilation (NIV) with active humidification is superior to a high-flow nasal cannula (HFNC) in preventing reintubation in patients with obesity at intermediate risk. Methods: We conducted a randomized controlled trial in two ICUs in Spain (June 2020-June 2021). We included patients ready for planned extubation with a body mass index >30 and three or fewer risk factors for reintubation. Patients with hypercapnia at the end of the spontaneous breathing trial were excluded. Patients were randomized to undergo NIV with active humidification or HFNC for 48 hours after extubation. The primary outcome was the reintubation rate within 7 days after extubation. As a secondary analysis, we performed a post hoc Bayesian analysis using three different priors. Measurements and Main Results: Of 144 patients (median age, 61 [25th-75th percentile range, 61-67] yr; 65 [45%] men), 72 received NIV and 72 received an HFNC. Reintubation was required in 17 (23.6%) patients receiving NIV and in 24 (33.3%) patients receiving HFNC (difference between groups, 9.7; 95% confidence interval, -4.9, 24.4). All of the secondary analysis showed nonsignificant differences. In the exploratory Bayesian analysis, the probability of a reduction in reintubation with NIV was 99% (data-driven prior), 90% (minimally informative prior), or 89% (skeptical prior). Conclusions: Among adult critically ill patients with obesity at intermediate risk for extubation failure, the rate of reintubation was not significantly lower with NIV than with HFNC. Nevertheless, there is a risk for underpowered results. Clinical trial registered with www.clinicaltrials.gov (NCT04125342).

BACKGROUND:The Air-Test score, which measures preoperative and postoperative Spo2 in room air, is associated with postoperative pulmonary complications (PPCs), a major cause of morbidity and mortality. We evaluated the utility of the Air-Test score in a heterogeneous population of surgical patients. METHODS:This secondary analysis of a harmonised dataset comprised 3268 patients included in three multicentre RCTs and a prospective observational study of surgical patients undergoing general anaesthesia. The patients were randomly split into training (n=2288, 70%) and validation (n=980, 30%) cohorts. The primary outcome was a composite of severe PPCs developing within the first 7 postoperative days. The exposure of interest was the Air-Test, evaluated by assessment of discriminative performance and area under the curve (AUC) calculation. We also assessed sensitivity, specificity, positive, and negative predictive values. RESULTS:Severe PPCs within 7 days of surgery were recorded in 164/3268 (5.0%) participants (mean age: 63.5 (49.7-77.3) yr; 39% female). Participants with a positive Air-Test were more likely to have severe PPCs in both training (odds ratio [OR] 1.85, 95% confidence interval [CI] 1.21-3.15; P=0.007) and validation (OR 2.27, 95% CI 1.27-4.61; P=0.011) cohorts. The AUCs for detecting PPCs in both cohorts were similar (OR 0.57, 95% CI 0.50-0.64). In each cohort, sensitivity was 53-54%, specificity 59-60%, positive predictive value 6-8%, and negative predictive value 95-96%. CONCLUSIONS:The Air-Test is a simple noninvasive bedside score with a good performance in identifying patients after major surgery who will not develop severe PPCs.

The Ideal Alveolar Gas Concept calculates the alveolar partial pressure of oxygen (PAO2) using arterial (PaCO2) instead of alveolar (PACO2) partial pressures of carbon dioxide in the alveolar gas equation. We compared the effects of shunt on PAO2 calculated by the "ideal" gas concept with a calculation using the multiple inert gas elimination technique (MIGET). We tested the hypothesis that shunt affects PACO2 and introduces significant errors in the estimation of PAO2 in two experimental porcine models. First, in a lung-lavage model (n = 10), shunt changes were induced by applying different levels of positive end-expiratory pressure. PaCO2 median 71 mmHg, (IQR 21 mmHg) was higher than MIGET PACO2 52(20) mmHg (p < 0.001). Ideal PAO2 654(33) mmHg was lower than MIGET PAO2 670(19) mmHg (p < 0.001). Bias in PAO2 was -23 mmHg with limits of agreement between 19 to -65 mmHg. Second, in a one-lung ventilation model (n = 10), changes in shunt were performed decreasing cardiac output by inferior vena cava balloon inflations (OLVCB), inhibiting hypoxic pulmonary constriction with nitroprusiate (OLVNPS) and increasing cardiac output with dobutamine (OLVDBT). Baseline PaCO2 was 55(10) mmHg and shunt 9(19)%. Cardiac output reduction did not affect PaCO2 57(9) mmHg (p = 0.19) or shunt 9(15)% (p = 0.570). Inhibiting hypoxic pulmonary vasoconstriction increased PaCO2 [62(13) mmHg; p = 0.083] and shunt [26(20)%; p = 0.020]. Cardiac output increase resulted in higher PaCO2 [67(11) mmHg; p = 0.004] and shunt [30(29)%; p = 0.012]. The assumption of the ideal gas concept that PaCO2 is not affected by shunt is incorrect introducing significant estimation errors in the alveolar gas equation.

Background: Acute Respiratory Distress Syndrome (ARDS) was first described in 1967 by Ashbaugh et al. as a severe acute hypoxemic respiratory failure with reduced lung compliance, representing a common end-path of severe pulmonary endothelial inflammation from diverse etiologies. Since then, several definitions for the adult syndrome have been proposed, culminating in the 2024 “New Global Definition” (Berlin 2.0). In pediatrics, dedicated criteria (pediatric ARDS, PARDS) have been established over the past decade, with the most recent update published by the Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2) in 2023. Methods: We performed a narrative literature review of consensus statements and key studies defining ARDS in adult and pediatric (non-neonatal) populations. Primary sources included the full Berlin 2.0 and PALICC-2 documents, supplemented by PubMed, Embase, and society guidelines. Definitions were compared across major diagnostic domains: timing of onset, imaging requirements, oxygenation thresholds, inclusion of patients with chronic comorbidities, ventilatory support modalities, and applicability in resource-limited settings. Results: Both definitions show convergence in incorporating non-invasive oxygenation indices and adaptability to resource-limited contexts. Key distinctions include the use of the Oxygenation Index (OI) or Oxygen Saturation Index (OSI) in invasively ventilated pediatric patients—metrics that integrate mean airway pressure and correlate more strongly than PaO2/FIO2 with short-term outcomes—and PALICC-2’s explicit inclusion of patients with chronic lung disease or cyanotic congenital heart disease when acute deterioration is documented. Imaging criteria differ, with Berlin 2.0 requiring bilateral opacities (and permitting lung ultrasound) versus PALICC-2’s acceptance of unilateral findings. Conclusions: Berlin 2.0 and PALICC-2 represent substantial progress toward globally applicable ARDS definitions, but physiologic and structural differences remain. These distinctions have prognostic and research implications, and harmonization will be critical to improve cross-age comparability, optimize clinical trial design, and ultimately enhance patient outcomes.

Background: Mixed trial results suggest that some ventilated patients with acute respiratory distress syndrome (ARDS) benefit from high PEEP while others may be harmed, indicating heterogeneity of treatment effect (HTE). This study applies data-driven predictive approaches to uncover HTE and re-examines previously hypothesized HTE. This manuscript serves as a pre-registration of planned external validation of our trained models. Methods: We identified eight randomized trials, and obtained individual patient data (IPD) from three of them (ALVEOLI, LOVS, EXPRESS), as our train cohort. We used effect modelling to predict individualized treatment effects (predicted 28-day mortality risk difference between PEEP strategies) across patient subgroups stratified by observed tertiles (<=8 cmH2O, 9-11 cmH2O, >=12 cmH2O). Candidate effect modelling methods included meta-learners and technique-specific methods. Optimal methods were selected through 'leave-one-trial-out' cross-validation, evaluating the methods' performances in each PEEP tertile using AUC-benefit. We trained final models using the best performing methods implemented with or without forward selection (which yielded sufficient AUC-benefit), and additional final models by selecting the variables that yielded consistency in the forward selections performed in the cross validation, if any. We further evaluated earlier hypothesized HTE comparing (1) patients with baseline PaO2/FiO2 <=200 versus >200 mmHg, and (2) patients with hypoinflammatory versus hyperinflammatory subphenotypes. Preliminary findings: In the lower PEEP tertile (<=8 cmH2O), an X-learner implemented without, and an S-learner implemented with forward selection (both with flexible base learners), yielded the highest AUC benefits and were used to train final models. In the high PEEP tertile (>=12 cmH2O), only the causal forest implemented with forward selection yielded an AUC benefit exceeding zero. Respiratory-system compliance (CRS) was consistently selected in the forward selections of cross validation, and was used to train an extra final causal forest model, with predicted effects shifting from harm to benefit for CRS 26.5 mL/cmH2O or higher. Higher PEEP benefited patients with baseline PaO2/FiO2 <=200 mmHg (OR 0.80, 95% CI 0.66-0.98), incurred harm among those with PaO2;/FiO2 >200 mmHg (OR 1.74, 95% CI 1.02-2.98; interaction P=0.01). This HTE was strongest when PaO2/FiO2 was measured at low PEEP (<=8 cmH2O), reduced at mid-level PEEP (9-11 cmH2O), and negligible at high PEEP (>=12 cmH2O). A second-order interaction showed significant heterogeneity of HTE (ie, second-order heterogeneity) across PEEP tertiles (P=0.03). Preliminary Conclusions: Our preliminary findings indicated that baseline CRS >=26.5 mL/cmH2O predicts benefit, while CRS <26.5 mL/cmH2O predicts harm from high PEEP when CRS is measured at high baseline PEEP (>=12 cmH2O). Similarly, baseline PaO2/FiO2; <=200 mmHg predicts benefit, while PaO2/FiO2 >200 mmHg predicts harm from high PEEP when PaO2/FiO2 is measured at a low baseline PEEP (<=8 cmH2O). Using data from the LOVS trial, we investigated HTE for high PEEP between hypo- and hyperinflammatory subphenotypes but found none, despite significant HTE observed earlier in the ALVEOLI trial. ### Competing Interest Statement A.H. Jonkman declares research funding paid to the institution by Pulmotech B.V., for validation of new esophageal pressure sensor. D. Talmor declares support from the National Institutes of Health and lecture honoraria from Mindray. J. Villar was funded by Instituto de Salud Carlos III, Madrid, Sapin (CB06/06/1088, PI19/00141, AC-21\_2/00039), ERAPerMed(JTC\_2021), ERAPerMed(JTC_2021), The European Regional Development Funds, Fundacion Canaria Intituto de Investigacipn Sanitaria de Canarias, and Asociacion Cientifica Pulmon y Ventilacion Mecanica. C.S. Calfee declares grants from NIH, Roche Genentech, and Quantum Leap Healthcare Collaborative to her institution, consulting fees from Vasomune, Gen1e Life Sciences, NGM Bio, Cellenkos, Calcimedica, Arrowhead, EnliTISA, Novartis, and Merck, being speaker at a symposium on ESICM guidelines supported by Fisher-Paykel, a Patent on metagenomic sequencing for sepsis diagnosis (co-recipient) issued to Regents of University of California and Chan Zuckerberg BioHub, and being council member of the International Sepsis Forum (unpaid). ### Funding Statement This study did not receive any funding. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study included individual patient data from three randomized controlled trials. The trial by Mercat et al. enrolled patinets at 37 intensive care units in France, and their study protocol was approved for all centers by the ethics committee of the Angers University Hospital (Comite Consultatif de Protection des Personnes dans la Recherche Biomedicale), according to French law. The trial by Brower et al. enrolled patients at 23 hospitals of the National HeartLung, and Blood Institute (NHLBI) ARDS Clinical Trials Network, and was approved by the institutional review board of each hospital. The trial by Meade et al. enrolled patients in 30 hospitals in Canada, Australia, and Saudi Arabia, and the research ethics board of each hospital approved the trial. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors

Acute Respiratory Distress Syndrome (ARDS) is a leading cause of morbidity and mortality among critically ill patients, and mechanical ventilation (MV) plays a critical role in its management. One of the key parameters of MV is the level of positive end-expiratory pressure (PEEP), which helps to maintain an adequate lung functional volume. However, the optimal level of PEEP remains controversial. The classical approach in clinical trials for identifying the optimal PEEP has been to compare “high” and “low” levels in a dichotomous manner. High PEEP can improve lung compliance and significantly enhance oxygenation but has been inconclusive in hard clinical outcomes such as mortality and duration of MV. This discrepancy could be related to the fact that inappropriately high or low PEEP levels may adversely affect other organs, such as the heart, brain, and kidneys, which could counteract its potential beneficial effects on the lung. Patients with ARDS often develop acute kidney injury, which is an independent marker of mortality. Three primary mechanisms have been proposed to explain lung-kidney crosstalk during MV: gas exchange abnormalities, such as hypoxemia and hypercapnia; remote biotrauma; and hemodynamic changes, including reduced venous return and cardiac output. As PEEP levels increase, lung volume expands to a variable extent depending on mechanical response. This dynamic underlies two potential mechanisms that could impair venous return, potentially leading to splanchnic and renal congestion. First, increasing PEEP may enhance lung aeration, particularly in highly recruitable lungs, where previously collapsed alveoli reopen, increasing lung volume and pleural pressure, leading to vena cava compression, which can contribute to systemic venous congestion and abdominal organ impairment function. Second, in lungs with low recruitability, PEEP elevation may induce minimal changes in lung volume while increasing airway pressure, resulting in alveolar overdistension, vascular compression, and increased pulmonary vascular resistance. Therefore, we propose that high PEEP settings can contribute to renal congestion, potentially impairing renal function. This review underscores the need for further rigorous research to validate these perspectives and explore strategies for optimizing PEEP settings while minimizing adverse renal effects.

Introduction: Right ventricular (RV) dysfunction is a frequently complicates cardiac surgery patients after cardiopulmonary-bypass. An underrecognized factor is the presence of lung collapse that affects RV afterload by increasing pulmonary vascular resistance. In this study studied the effects of inhaled intric oxide (iNO) alone or in combination with lung recruitment to mitigate the effects of lung collapse on RV function after cardiac surgeryMethods: We included patients with preserved heart function, without pulmonary hypertension or lung disease that underwent uncomplicated coronary or valvular heart surgery under cardiopulmonary by-pass without the need of peri-opearative inotropes that presented post-operative lung collapse: compliance (Crs) ≤35ml/cmH2O, and dorsal electrical impedance tomography(EIT) relative ventilatio distribution <40%. Patients were randomized to either control: standard post-operative management; iNO: 60 min of 40ppm and RM-iNO: lung recruitment and post recruitment PEEP 10 – 12 cmH2O + 60 min of 40ppm. Gas exchange, lung mechanics, hemodynamic parameters, EIT relative distriburtion of ventilation-perfusion and evaluation of RV function by transoesophageal echocardiography (TEE) were obtained at baseline and after 60 min. Results: We included 13 patient in this preliminary analysis. 10 Female, Median age 65(55-76), mean BMI 30±4. Coronary surgery, valvular surgery: Pre-operative left ventricular ejection fracion 65±9%. At baseline EIT dorsal ventilation was 34±4% and Crs 35±4 ml/cmHO2. In the control and iNO groups PEEP remained at 5 cmH2O and increased to 12 in the RM-iNO (Table). Gas exchange, lung mechanics, hemodynamics, EIT distribution of ventilation and perfusion and TEE-derived RV function parameters remained unchanged in the control group (Table). In the iNO group lung mechanics and EIT distributions ventilation were similar at the end of the protocol. EIT distribution of relative pulmonary perfusion significantly increased from 35 to 45% in the ventral regions. This resulted in an improvement in oxygenation. TEE determined pulmonary artery systolic pressure decreased (PAPs) by 8% and stroke volume by 10%. Respecting RV function contractilty parameters slightly improved and the right ventricle ejection efficiency a parameter intimately related to ventricular vascular coupling. In the RM-iNO group PaO2/FiO2, Compliance increased and driving pressure decreased. This corresponded to an increase in dorsal ventilation from 29 to 44 % and in ventral perfusion from 51 to 56%. PAPs and all RV parameters improved especially the fractional area change. Conclusions: Post-operative use of iNO improved PAPs and and RV function especially ventricular vascular coupling in patient with lung collapse. These effects were enhanced by combining effective lung recruitment.

BACKGROUND:High mortality rates among patients with chronic obstructive pulmonary disease (COPD) admitted to intensive care units (ICUs) during the COVID-19 pandemic highlight the need for tailored clinical management strategies. STUDY DESIGN AND METHODS:Epidemiological, clinical, and laboratory data were collected in REDCap for 6512 patients hospitalized with COVID-19 across 55 Spanish ICUs. Patients were stratified into three groups: those with COPD, those with other chronic respiratory diseases (CRD), and those without respiratory comorbidities (No CRD). The primary outcome was to determine clinical predictors for 90-day mortality, focusing on the COPD group. A propensity score matching (PSM) method was applied to analyze the effects of respiratory support, biomarkers, and immunomarkers. RESULTS:Patients with COPD (n = 328) exhibited a 50% mortality rate compared to 33% of those with other chronic respiratory diseases (CRD, n = 547), and those without respiratory comorbidities (No CRD, n = 5124). Among COPD patients, 95% of whom had Acute Respiratory Distress Syndrome (ARDS) due to COVID-19, the use of a high-flow nasal cannula (HFNC) was associated with reduced 90-day mortality (hazard ratio: 0.54 (95% Confidence Interval [0.31-0.95]). At a molecular scale, lower IgG levels but higher viral load and TNF-alpha, Vascular Cell Adhesion Molecule-1 (VCAM-1), and Fas Cell Surface Death Receptor (Fas) were associated with mortality in the COPD group. CONCLUSIONS:In COPD patients with ARDS due to COVID-19, the use of HFNC was associated with a better prognosis. The dysregulation in biomarkers and immunomarkers in COPD patients and its association with mortality highlight the need for further targeted therapeutic strategies.

COVID-19 severely impacted global health, especially older adults and those with comorbidities. Immunosuppressed patients are at high risk for severe outcomes, yet studies yield conflicting mortality rates for this group. This study examines the clinical characteristics and outcomes of immunosuppressed (IS) versus non-immunosuppressed (nIS) patients with COVID-19 in ICUs. A multicenter, observational case–control study included 5,824 ICU patients with COVID-19 from the CIBERESUCICOVID study. Patients were categorized as IS or nIS based on history of transplantation, HIV, active neoplasia, and use of immunosuppressive drugs or corticosteroids. The primary outcome was 90-day mortality; secondary outcomes included in-hospital, 15-day, 30-day and 1-year mortality, ICU-free days, ventilator-free days, and hospital length of stay. Subgroup analyses examined vaccination status and tocilizumab treatment. Propensity score (PS) matching was used to obtain balance among the baseline variables in the two groups. IS patients (n = 689, 11.8