Fluid Therapy and Acute Respiratory Distress Syndrome

IL-33 facilitates endoplasmic reticulum stress and pyroptosis in LPS-stimulated ARDS model in vitro

BACKGROUND

Inflammatory activation of pulmonary microvascular endothelial cells (PMVECs) initiated by endoplasmic reticulum stress (ERS) contributes to acute respiratory distress syndrome (ARDS). Interleukin 33 (IL-33) has pro-inflammatory and transcriptional regulatory effects. Therefore, this study intends to investigate the effect of IL-33 on ERS and pyroptosis in the hPMVEC.

METHODS

The hPMVEC-associated ARDS cell model was induced with lipopolysaccharide (LPS) and treated with 4-PBA (ERS inhibitor), thapsigargin (ERS activator), or IL-33 neutralizing antibody. Western blot and IF staining were performed to analyze the expression of cell-cell junction-associated (Cx37, Cx40, Cx43, Occludin, and Zo-1), ERS-associated (ATF6, IRE1a, and p-Erk), and pyroptosis-associated (NLRP3, IL-1β, and IL-18) proteins. Bioinformatics identified differential expression of IL-33 in ARDS-related datasets and targets of thapsigargin.

RESULTS

IL-33 was highly expressed in serum of ARDS patients and in ARDS cohorts from multiple GEO datasets (GSE237260, GSE216635, GSE89953, GSE263867, and GSE5883), and was significantly correlated with clinical features. 4-PBA decreased permeability and IL-33 levels, and increased Cx37, Cx40 and Cx43 levels in the ARDS cell model. IL-33 neutralizing antibody effectively augmented the levels of Cx43 and Zo-1, and diminished the levels of ATF6, IRE1a, p-Erk, NLRP3, IL-1β, IL-18, ROS, and Ca2 +. The therapeutic effect of IL-33 neutralizing antibodies was reverted by thapsigargin. Moreover, the Swiss Target Prediction and Super-PRED databases obtained 140 and 122 thapsigargin targets, which had 14 intersections. These intersections were associated with immunity, inflammation, apoptosis, pyroptosis, and Ca2+ homeostasis. Notably, CASP8 and PTGS2 interacted with IL-33 in these intersections.

CONCLUSION

IL-33 promotes ERS and pyroptosis, thereby contributing to barrier damage in ARDS cell models. IL-33 is a promising therapeutic target for ARDS.

Respiratory manifestations of rickettsial disease in tropical Australia; Clinical course and implications for patient management

BACKGROUND

Rickettsial infections have a global distribution and can cause life-threatening disease. Respiratory symptoms can be a harbinger of a more complicated disease course. However, the clinical associations - and the clinical course - of patients with rickettsial disease and respiratory involvement are incompletely defined.

METHODS

This was a retrospective study of all patients with a diagnosis of scrub typhus or Queensland tick typhus (QTT) managed at Cairns Hospital in tropical Australia, between 1st January 1997 and 31st October 2023. We determined the demographic, clinical, radiological and laboratory associations of respiratory involvement which was defined as any acute abnormality of lung parenchyma identified on thoracic imaging during their hospitalisation that did not have another more likely explanation. We compared the clinical course of patients with a rickettsial infection who did - and did not - have respiratory involvement.

RESULTS

There were 226 individuals included in the analysis, 51/226 (22 %) had respiratory involvement, including 18/59 (31 %) with QTT and 33/167 (20 %) with scrub typhus, p = 0.09. The imaging findings were heterogenous: 33/51 (65 %) had predominantly alveolar changes, 18/51 (35 %) had interstitial changes and 12/51 (24 %) had a pleural effusion. Those with respiratory involvement were older than individuals without respiratory involvement (median (interquartile range (IQR)) age 51 (37-65) years versus 38 (25-51) years (p = 0.0001). However, most patients (27/51, 53 %) with respiratory involvement had no comorbidity and were younger than 60. Patients with respiratory involvement were more likely to require ICU admission that patients without respiratory involvement (19/51 (38 %) versus 6/175 (3 %) p < 0.001) and 9/51 (18 %) with respiratory involvement required mechanical ventilation. Patients with respiratory involvement were also more likely to require vasopressor support (14/51, 27 % versus 4/175, 2 %, p < 0.001) and renal replacement therapy (4/51, 8 % versus 1/175, 0.6 %, p = 0.01) than patients without respiratory involvement. There were 2/226 (1 %) individuals who died from their rickettsial infection (1 scrub typhus and 1 QTT) during the study period, both had respiratory involvement.

CONCLUSIONS

Respiratory involvement is common in individuals with rickettsial infection in tropical Australia and is associated with a greater risk of life-threatening disease.

Tangled culprit: a rare case of bezoar-induced small bowel obstruction with pulmonary Edema in a rural Guatemalan woman

We present the unusual case of a 52-year-old woman from a low-resource community in Guatemala who developed small bowel obstruction, followed by acute pulmonary edema. The patient had no prior history of abdominal surgeries or significant comorbidities, making this presentation unexpected. The obstruction was caused by a bezoar and complicated by fluid overload during resuscitation. Radiologic findings revealed dilated bowel loops, suggesting bowel obstruction, and Kerley B lines, indicating concurrent pulmonary edema. This report underscores the challenges of managing complex emergencies in resource-limited settings, highlighting the importance of timely surgical intervention and careful fluid management.

Establishment and validation of predictive model of ARDS in critically ill patients

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a prevalent complication among critically ill patients, constituting around 10% of intensive care unit (ICU) admissions and mortality rates ranging from 35 to 46%. Hence, early recognition and prediction of ARDS are crucial for the timely administration of targeted treatment. However, ARDS is frequently underdiagnosed or delayed, and its heterogeneity diminishes the clinical utility of ARDS biomarkers. This study aimed to observe the incidence of ARDS among high-risk patients and develop and validate an ARDS prediction model using machine learning (ML) techniques based on clinical parameters.

METHODS

This prospective cohort study in China was conducted on critically ill patients to derivate and validate the prediction model. The derivation cohort, consisting of 400 patients admitted to the ICU of the Peking University Third Hospital(PUTH) between December 2020 and August 2023, was separated for training and internal validation, and an external data set of 160 patients at the FU YANG People's Hospital from August 2022 to August 2023 was employed for external validation. Least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression were used to screen predictor variables. Multiple ML classification models were integrated to analyze and identify the best models. Several evaluation indexes were used to compare the model performance, including the area under the receiver-operating-characteristic curve (AUC) and decision curve analysis (DCA). SHapley Additive ex Planations (SHAP) is used to interpret ML models.

RESULTS

400 critically ill patients were included in the analysis, with 117 developing ARDS during follow-up. The final model included gender, Lung Injury Prediction Score (LIPS), Hepatic Disease, Shock, and combined Lung Contusion. Based on the AUC and DCA in the validation group, the logistic model demonstrated excellent performance, achieving an AUC of 0.836 (95% CI: 0.762-0.910). For external validation, comprising 160 patients, 44 of whom developed ARDS, the AUC was 0.799 (95% CI: 0.723-0.875), significantly outperforming the LIPS score alone.

CONCLUSION

Combining the LIPS score with other clinical parameters in a logistic regression model provides a more accurate, clinically applicable, and user-friendly ARDS prediction tool than the LIPS score alone.

New Insights on Continuous Renal Replacement Therapy for Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

BACKGROUND

In recent times, the applications of continuous renal replacement therapy (CRRT) beyond kidney-related conditions have been progressively increasing, and its implementation in randomized controlled trials (RCTs) specifically for acute respiratory distress syndrome (ARDS) has been documented. This meta-analysis compiles all existing RCTs to assess whether CRRT benefits ARDS.

METHODS

We searched 12 databases in English and Chinese and two clinical trial centers up to November 28, 2023. The main outcome indicator is the mortality rate. Secondary outcome indicators include incidence of ventilator-associated pneumonia (VAP), ICU length of stay, mechanical ventilation time, oxygenation index (OI) at 24 h (h), OI at 48 h, OI at 72 h, OI at 7 days (d), partial pressure of oxygen (PaO2) at 72 h, Acute Physiology and Chronic Health Evaluation II (APACHE II) score at 24 h, APACHE II score at 48 h, APACHE II score at 72 h, APACHE II score at 7 d, extravascular lung water indexes (EVLWI) at 72 h, TNF-α at 24 h, TNF-α at 7 d, IL-6 at 24 h, IL-6 at 48 h, IL-6 at 72 h, and IL-6 at 7 d. Statistical measures utilized include risk ratios (RR), weighted mean difference (WMD), and 95% confidence intervals (95% CI).

RESULTS

We summarized 36 studies, including 2123 patients. It was found that for ARDS, using CRRT in addition to conventional therapy can reduce the mortality rate (I2 = 0%; RR: 0.40; 95% CI: 0.30-0.53; p < 0.01), the incidence of VAP (I2 = 0%; RR: 0.44; 95% CI: 0.33-0.59; p < 0.01), ICU length of stay, mechanical ventilation time, and EVLWI at 72 h, as well as APACHE II score, TNF-α, and IL-6 at various time points. Additionally, it can increase OI during different time intervals and PaO2 at 72 h.

CONCLUSIONS

Low-quality evidence suggests that compared with conventional therapy alone, the use of CRRT may be associated with a lower mortality rate, the incidence of VAP, ICU length of stay, mechanical ventilation time, EVLWI, APACHE II score, TNF-α, and IL-6 and may be related to better respiratory function. CRRT may be beneficial for ARDS patients. Future multicenter, well-designed, high-quality RCTs are needed to substantiate these findings.

Research progress of mitochondrial dysfunction induced pyroptosis in acute lung injury

Acute lung injury (ALI) is a common critical respiratory disease in clinical practice, especially in the ICU, with a high mortality rate. The pathogenesis of ALI is relatively complex, mainly involving inflammatory response imbalance, oxidative stress, cell apoptosis, and other aspects. However, currently, the treatment measures taken based on the above mechanisms have not had significant effects. Recent research shows that mitochondrial dysfunction and pyroptosis play an important role in ALI, but there is not much analysis on the relationship between mitochondrial dysfunction and pyroptosis at present. This article reviews the situation of mitochondrial dysfunction in ALI, pyroptosis in ALI, whether mitochondrial dysfunction is related to pyroptosis in ALI, and how to do so, and further analyzes the relationship between them in ALI. This review describes how to alleviate mitochondrial dysfunction, and then suppress the associated immunological pyroptosis, providing new ideas for the clinical treatment of ALI.

Advancements in understanding the mechanisms of lung-kidney crosstalk

This narrative review delves into the intricate interplay between the lungs and the kidneys, with a focus on elucidating the pathogenesis of diseases influenced by immunological factors, acid-base regulation, and blood gas disturbances, as well as assessing the effects of various therapeutic modalities on these interactions. Key disorders, such as anti-glomerular basement membrane (anti-GBM) disease, the syndrome of inappropriate antidiuretic hormone secretion (SIADH), and Anti-neutrophil Cytoplasmic Antibodies (ANCA) associated vasculitis (AAV), are also examined to shed light on their underlying mechanisms. This review also explores the relationship between acute respiratory distress syndrome (ARDS) and acute kidney injury (AKI), emphasizing how inflammatory mediators can lead to systemic damage and impact multiple organs. In ARDS, fluid overload exacerbates pulmonary edema, while imbalances in blood volume, such as hypovolemia or hypervolemia, can precipitate renal dysfunction. The review highlights how mechanical ventilation strategies can compromise renal blood flow, trigger systemic inflammation, and induce hemodynamic and neurohormonal alterations, all contributing to lung and kidney damage. The impact of extracorporeal membrane oxygenation (ECMO) on lung-kidney interactions is evaluated, highlighting its role in severe respiratory failure and its renal implications. Emerging therapies, such as mesenchymal stem cells and extracellular vesicles, are discussed as promising avenues to mitigate organ damage and enhance outcomes in critically ill patients. Overall, this review offers a nuanced exploration of lung-kidney dynamics, bridging historical insights with contemporary perspectives. It underscores the clinical significance of these interactions in critically ill patients and advocates for integrated management approaches to optimize patient outcomes.

Relationship between ferroptosis and mitophagy in acute lung injury: a mini-review

Acute lung injury (ALI) is one of the most deadly and prevalent diseases in the intensive care unit. Ferroptosis and mitophagy are pathological mechanisms of ALI. Ferroptosis aggravates ALI, whereas mitophagy regulates ALI. Ferroptosis and mitophagy are both closely related to reactive oxygen species (ROS). Mitophagy can regulate ferroptosis, but the specific relationship between ferroptosis and mitophagy is still unclear. This study summarizes previous research findings on ferroptosis and mitophagy, revealing their involvement in ALI. Examining the functions of mTOR and NLPR3 helps clarify the connection between ferroptosis and mitophagy in ALI, with the goal of establishing a theoretical foundation for potential therapeutic approaches in the future management of ALI.

Interorgan communication networks in the kidney-lung axis

The homeostasis and health of an organism depend on the coordinated interaction of specialized organs, which is regulated by interorgan communication networks of circulating soluble molecules and neuronal connections. Many diseases that seemingly affect one primary organ are really multiorgan diseases, with substantial secondary remote organ complications that underlie a large part of their morbidity and mortality. Acute kidney injury (AKI) frequently occurs in critically ill patients with multiorgan failure and is associated with high mortality, particularly when it occurs together with respiratory failure. Inflammatory lung lesions in patients with kidney failure that could be distinguished from pulmonary oedema due to volume overload were first reported in the 1930s, but have been largely overlooked in clinical settings. A series of studies over the past two decades have elucidated acute and chronic kidney-lung and lung-kidney interorgan communication networks involving various circulating inflammatory cytokines and chemokines, metabolites, uraemic toxins, immune cells and neuro-immune pathways. Further investigations are warranted to understand these clinical entities of high morbidity and mortality, and to develop effective treatments.

Pulmonary reperfusion injury in post-palliative intervention of oligaemic cyanotic CHD: a new catastrophic consequence or just revisiting the same old story?

Pulmonary reperfusion injury is a well-recognised clinical entity in the setting pulmonary artery angioplasty for pulmonary artery stenosis or chronic thromboembolic disease, but not much is known about this complication in post-palliative intervention of oligaemic cyanotic CHD. The pathophysiology of pulmonary reperfusion injury in this population consists of both ischaemic and reperfusion injury, mainly resulting in oxidative stress from reactive oxygen species generation, followed by endothelial dysfunction, and cytokine storm that may induce multiple organ dysfunction. Other mechanisms of pulmonary reperfusion injury are "no-reflow" phenomenon, overcirculation from high pressure in pulmonary artery, and increased left ventricular end-diastolic pressure. Chronic hypoxia in cyanotic CHD eventually depletes endogenous antioxidant and increased the risk of pulmonary reperfusion injury, thus becoming a concern for palliative interventions in the oligaemic subgroup. The incidence of pulmonary reperfusion injury varies depending on multifactors. Despite its inconsistence occurrence, pulmonary reperfusion injury does occur and may lead to morbidity and mortality in this population. The current management of pulmonary reperfusion injury is supportive therapy to prevent deterioration of lung injury. Therefore, a general consensus on pulmonary reperfusion injury is necessary for the diagnosis and management of this complication as well as further studies to establish the use of novel and potential therapies for pulmonary reperfusion injury.

Optimizing Fluid Management Guided by Volumetric Parameters in Patients with Sepsis and ARDS

We compared two de-escalation strategies guided by either extravascular lung water or global end-diastolic volume-oriented algorithms in patients with sepsis and ARDS. Sixty patients with sepsis and ARDS were randomized to receive de-escalation fluid therapy, guided either by the extravascular lung water index (EVLWI, n = 30) or the global end-diastolic volume index (GEDVI, n = 30). In cases of GEDVI > 650 mL/m² or EVLWI > 10 mL/kg, diuretics and/or controlled ultrafiltration were administered to achieve the cumulative 48-h fluid balance in the range of 0 to -3000 mL. During 48 h of goal-directed de-escalation therapy, we observed a decrease in the SOFA score (p < 0.05). Extravascular lung water decreased only in the EVLWI-oriented group (p < 0.001). In parallel, PaO₂/FiO₂ increased by 30% in the EVLWI group and by 15% in the GEDVI group (p < 0.05). The patients with direct ARDS demonstrated better responses to dehydration therapy concerning arterial oxygenation and lung fluid balance. In sepsis-induced ARDS, both fluid management strategies, based either on GEDVI or EVLWI, improved arterial oxygenation and attenuated organ dysfunction. The de-escalation therapy was more efficient for direct ARDS.

The Intensivist's Perspective of Shock, Volume Management, and Hemodynamic Monitoring

One of the primary reasons for intensive care admission is shock. Identifying the underlying cause of shock (hypovolemic, distributive, cardiogenic, and obstructive) may lead to entirely different clinical pathways for management. Among patients with hypovolemic and distributive shock, fluid therapy is one of the leading management strategies. Although an appropriate amount of fluid administration might save a patient's life, inadequate (or excessive) fluid use could lead to more complications, including organ failure and mortality due to either hypovolemia or volume overload. Currently, intensivists have access to a wide variety of information sources and tools to monitor the underlying hemodynamic status, including medical history, physical examination, and specific hemodynamic monitoring devices. Although appropriate and timely assessment and interpretation of this information can promote adequate fluid resuscitation, misinterpretation of these data can also lead to additional mortality and morbidity. This article provides a narrative review of the most commonly used hemodynamic monitoring approaches to assessing fluid responsiveness and fluid tolerance. In addition, we describe the benefits and disadvantages of these tools.