Acute Kidney Injury and Acute Respiratory Distress Syndrome

Lung-Kidney Axis in Cystic Fibrosis: Early Urinary Markers of Kidney Injury Correlate with Neutrophil Activation and Worse Lung Function

Background

Adult people with cystic fibrosis (PwCF) have a higher risk of end-stage kidney disease than the general population. The nature and mechanism of kidney disease in CF are unknown. This study quantifies urinary kidney injury markers and examines the hypothesis that neutrophil activation and lung infection are associated with early kidney injury in CF.

Methods

Urinary total protein, albumin, and markers of kidney injury and neutrophil activation, normalized to creatinine, as well as urinary immune cells, were quantified in CF (n = 48) and healthy (n = 33) cohorts. Infection burden and chronicity were defined by sputum culture and serum titers of anti-bacterial antibodies.

Results

PwCF had increased urinary protein levels, consisting of low-molecular-weight tubular injury markers, independent of glomerular filtration rate (eGFR). This finding suggests subclinical renal injury processes. Urinary analysis of the CF cohort identified different associations of urinary injury markers with aminoglycoside exposure, lung function, and neutrophil activation. High urinary KIM-1 levels and increased prevalence of neutrophils among urine immune cells correlated with decreased lung function in PwCF. The relationship between tubular injury and decreased lung function was most prominent in patients harboring chronic Pseudomonas aeruginosa infection.

Conclusions

Increased urinary tubular injury markers in PwCF suggest early subclinical renal injury not readily detected by eGFR. The strong association of high urinary KIM-1 and neutrophils with diminished lung function and high Pseudomonas aeruginosa burden suggests that pulmonary disease may contribute to renal injury in CF.

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.

Hemodialysis vascular access in prone position for critically ill patients with ARDS

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is defined in critically ill patients with acute hypoxemia and positive-pressure ventilation in association with several clinical disorders including trauma, pneumonia, sepsis, and aspiration. The prone position has been used for many years and is now recommended for patients with severe or moderate-to-severe ARDS on invasive mechanical ventilation. Acute kidney injury (AKI) is a common complication in patients with ARDS, with up to a 35% incidence rate. Initiation of Kidney Replacement Therapy (KRT) requires wise clinical judgment and collaboration between nephrologists and intensivists. A properly functioning vascular access is critical for an optimized KRT. Our institute is a national referral center for respiratory diseases.

RESULTS

We describe 11 cases of dialysis catheter placement for KRT in critically ill patients with ARDS on mechanical ventilation in prone position. The catheter was placed in the first puncture attempt in nine cases, Blood flows (Qb) achieved were 283.4 ± 20.4 ml/min during the session, in six cases the radiologic tip location was achieved in the peri cavoatrial junction; in four cases was achieved in mid to- deep right atrium. The dialysis quality standards were based on KTV and in URR; in nine cases (81.81%) KTV was in 1.3 and in all cases (100%) URR was >65%, lumen dysfunction was reported only in two cases (18.1%), but these cases did respond to mobilization maneuvers. The procedure time of placement was 29.8 min, no arterial punctures or complications were reported.

CONCLUSIONS

We demonstrate that in our study hemodialysis non-tunneled catheter placement in the prone position is safe and effective. We believe this practice could be frequently used in the near future and represent an opportunity window for the training of interventional nephrologists and related areas.

Acute kidney injury comorbidity analysis based on international classification of diseases-10 codes

OBJECTIVE

Acute kidney injury (AKI) is a clinical syndrome that occurs as a result of a dramatic decline in kidney function caused by a variety of etiological factors. Its main biomarkers, serum creatinine and urine output, are not effective in diagnosing early AKI. For this reason, this study provides insight into this syndrome by exploring the comorbidities of AKI, which may facilitate the early diagnosis of AKI. In addition, organ crosstalk in AKI was systematically explored based on comorbidities to obtain clinically reliable results.

METHODS

We collected data from the Medical Information Mart for Intensive Care-IV database on patients aged [Formula: see text] 18 years in intensive care units (ICU) who were diagnosed with AKI using the criteria proposed by Kidney Disease: Improving Global Outcomes. The Apriori algorithm was used to mine association rules on the diagnoses of 55,486 AKI and non-AKI patients in the ICU. The comorbidities of AKI mined were validated through the Electronic Intensive Care Unit database, the Colombian Open Health Database, and medical literature, after which comorbidity results were visualized using a disease network. Finally, organ diseases were identified and classified from comorbidities to investigate renal crosstalk with other distant organs in AKI.

RESULTS

We found 579 AKI comorbidities, and the main ones were disorders of lipoprotein metabolism, essential hypertension, and disorders of fluid, electrolyte, and acid-base balance. Of the 579 comorbidities, 554 were verifiable and 25 were new and not previously reported. In addition, crosstalk between the kidneys and distant non-renal organs including the liver, heart, brain, lungs, and gut was observed in AKI with the strongest heart-kidney crosstalk, followed by lung-kidney crosstalk.

CONCLUSION

The comorbidities mined in this study using association rules are scientific and may be used for the early diagnosis of AKI and the construction of AKI predictive models. Furthermore, the organ crosstalk results obtained through comorbidities may provide supporting information for the management of short- and long-term treatment practices for organ dysfunction.

Accuracy of the persistent AKI risk index in predicting acute kidney injury in patients admitted to the intensive care unit for acute respiratory failure

OBJECTIVE

To evaluate the accuracy of the persistent AKI risk index (PARI) in predicting acute kidney injury within 72 hours after admission to the intensive care unit, persistent acute kidney injury, renal replacement therapy, and death within 7 days in patients hospitalized due to acute respiratory failure.

METHODS

This study was done in a cohort of diagnoses of consecutive adult patients admitted to the intensive care unit of eight hospitals in Curitiba, Brazil, between March and September 2020 due to acute respiratory failure secondary to suspected COVID-19. The COVID-19 diagnosis was confirmed or refuted by RT-PCR for the detection of SARS-CoV-2. The ability of PARI to predict acute kidney injury at 72 hours, persistent acute kidney injury, renal replacement therapy, and death within 7 days was analyzed by ROC curves in comparison to delta creatinine, SOFA, and APACHE II.

RESULTS

Of the 1,001 patients in the cohort, 538 were included in the analysis. The mean age was 62 ± 17 years, 54.8% were men, and the median APACHE II score was 12. At admission, the median SOFA score was 3, and 83.3% had no renal dysfunction. After admission to the intensive care unit, 17.1% had acute kidney injury within 72 hours, and through 7 days, 19.5% had persistent acute kidney injury, 5% underwent renal replacement therapy, and 17.1% died. The PARI had an area under the ROC curve of 0.75 (0.696 - 0.807) for the prediction of acute kidney injury at 72 hours, 0.71 (0.613 - 0.807) for renal replacement therapy, and 0.64 (0.565 - 0.710) for death.

CONCLUSION

The PARI has acceptable accuracy in predicting acute kidney injury within 72 hours and renal replacement therapy within 7 days of admission to the intensive care unit, but it is not significantly better than the other scores.

Development and validation of risk prediction nomograms for acute respiratory failure in elderly patients with hip fracture

BACKGROUND

Hip fractures in the elderly often lead to acute respiratory failure, but there is currently no tool to assess the prognosis of such patients. This study aims to develop a risk prediction model for respiratory failure in these patients.

METHODS

A retrospective cross-sectional study was conducted using the Medical Information Mart for Intensive Care (MIMIC)-IV database, incorporating data from 3,266 patients with hip fractures aged over 55 years from 2008 to 2019. Data included demographic information, laboratory indicators, comorbidities, and treatment methods. Patients were divided into a training group (70%) and a validation group (30%). Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to select prognostic predictors, and a visualized nomogram model was constructed using multivariate logistic regression analysis. Model performance and clinical applicability were assessed. Statistical analyses were done using R4.2.2, with P < 0.05 deemed significant.

RESULTS

Seven key factors, including age, height, albumin, chloride, pneumonia, acute kidney injury (AKI), and heparin use, were associated with respiratory failure risk. The model demonstrated good performance with area under the curve (AUC) values of 0.77 and 0.73 in the training and validation sets, respectively. The calibration curve showed good agreement, and decision curve analysis (DCA) indicated the model's clinical benefit.

CONCLUSIONS

This risk prediction model can effectively predict respiratory failure in hip fracture patients, assisting clinicians in identifying high-risk individuals and providing evidence-based references for treatment strategies.

Early acute kidney injury and transition to renal replacement therapy in critically ill patients with SARS-CoV-2 requiring veno-venous extracorporeal membrane oxygenation

BACKGROUND

Critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requiring veno-venous extracorporeal membrane oxygenation (vv-ECMO) are at risk for acute kidney injury (AKI). Currently, the incidence of AKI and progression to kidney replacement therapy (RRT) in critically ill patients with vv-ECMO for severe COVID-19 and implications on outcome are still unclear.

METHODS

Retrospective analysis at the University Medical Center Hamburg-Eppendorf (Germany) between March 1st, 2020 and July 31st, 2021. Demographics, clinical parameters, AKI, type of organ support, length of ICU stay, mortality and severity scores were assessed.

RESULTS

Ninety-one critically ill patients with SARS-CoV-2 requiring ECMO were included. The median age of the study population was 57 (IQR 49-64) years and 67% (n = 61) were male. The median SAPS II and SOFA Score on admission were 40 (34-46) and 12 (10-14) points, respectively. We observed that 45% (n = 41) developed early-AKI, 38% (n = 35) late-AKI and 16% (n = 15) no AKI during the ICU stay. Overall, 70% (n = 64) of patients required RRT during the ICU stay, 93% with early-AKI and 74% with late-AKI. Risk factors for early-AKI were younger age (OR 0.94, 95% CI 0.90-0.99, p = 0.02) and SAPS II (OR 1.12, 95% CI 1.06-1.19, p < 0.001). Patients with and without RRT were comparable regarding baseline characteristics. SAPS II (41 vs. 37 points, p < 0.05) and SOFA score (13 vs. 12 points, p < 0.05) on admission were significantly higher in patients receiving RRT. The median duration of ICU (36 vs. 28 days, p = 0.27) stay was longer in patients with RRT. An ICU mortality rate in patients with RRT in 69% (n = 44) and in patients without RRT of 56% (n = 27) was observed (p = 0.23).

CONCLUSION

Critically ill patients with severe SARS-CoV-2 related ARDS requiring vv-ECMO are at high risk of early acute kidney injury. Early-AKI is associated with age and severity of illness, and presents with high need for RRT. Mortality in patients with RRT was comparable to patients without RRT.

Machine learning-based prediction model of acute kidney injury in patients with acute respiratory distress syndrome

BACKGROUND

Acute kidney injury (AKI) can make cases of acute respiratory distress syndrome (ARDS) more complex, and the combination of the two can significantly worsen the prognosis. Our objective is to utilize machine learning (ML) techniques to construct models that can promptly identify the risk of AKI in ARDS patients.

METHOD

We obtained data regarding ARDS patients from the Medical Information Mart for Intensive Care III (MIMIC-III) and MIMIC-IV databases. Within the MIMIC-III dataset, we developed 11 ML prediction models. By evaluating various metrics, we visualized the importance of its features using Shapley additive explanations (SHAP). We then created a more concise model using fewer variables, and optimized it using hyperparameter optimization (HPO). The model was validated using the MIMIC-IV dataset.

RESULT

A total of 928 ARDS patients without AKI were included in the analysis from the MIMIC-III dataset, and among them, 179 (19.3%) developed AKI after admission to the intensive care unit (ICU). In the MIMIC-IV dataset, there were 653 ARDS patients included in the analysis, and among them, 237 (36.3%) developed AKI. A total of 43 features were used to build the model. Among all models, eXtreme gradient boosting (XGBoost) performed the best. We used the top 10 features to build a compact model with an area under the curve (AUC) of 0.850, which improved to an AUC of 0.865 after the HPO. In extra validation set, XGBoost_HPO achieved an AUC of 0.854. The accuracy, sensitivity, specificity, positive prediction value (PPV), negative prediction value (NPV), and F1 score of the XGBoost_HPO model on the test set are 0.865, 0.813, 0.877, 0.578, 0.957 and 0.675, respectively. On extra validation set, they are 0.724, 0.789, 0.688, 0.590, 0.851, and 0.675, respectively.

CONCLUSION

ML algorithms, especially XGBoost, are reliable for predicting AKI in ARDS patients. The compact model maintains excellent predictive ability, and the web-based calculator improves clinical convenience. This provides valuable guidance in identifying AKI in ARDS, leading to improved patient outcomes.

Incidence, Outcomes, and Predictors of Subphenotypes of Acute Kidney Injury among Acute Respiratory Distress Syndrome Patients: A Prospective Observational Study

Background

Acute kidney injury (AKI) is a heterogeneous syndrome with subphenotypes. Acute kidney injury is one of the most common complications in acute respiratory distress syndrome (ARDS) patients, which influences mortality.

Material and methods

It was a single-center observational study on 266 ARDS patients on invasive mechanical ventilation (IMV) to determine the subphenotypes of AKI associated with ARDS. Subphenotyping was done based on the serum creatinine (SCr) trajectories from day 1 to day 5 of IMV into resolving (subphenotype 1) or non-resolving (subphenotype 2) AKI.

Results

Out of 266 ARDS patients, 222 patients were included for data analysis. 141 patients (63.51%) had AKI. The incidence of subphenotype 2 AKI among the ARDS cohort was 78/222 (35.13%). Subphenotype 2 AKI was significantly more among the non-survivors (87.7% vs 36.2 %, p < 0.001). Subphenotype 2 AKI was an independent predictor of mortality among ARDS patients (p < 0.001, adjusted odds ratio 8.978, 95% CI [2.790-28.89]. AKI subphenotype 1 had higher median day 1 SCr than subphenotype 2 but lower levels by day 3 and day 5 of IMV. The median time of survival was 8 days in AKI subphenotype 2 vs 45 days in AKI with subphenotype 1 [Log-Rank (Mantel-Cox) p < 0.001]. The novel DRONE score (Driving pressure, Oxygenation, and Nutritional Evaluation) ≥ 4 predicted subphenotype 2 AKI.

Conclusion

The incidence of subphenotype 2 (non-resolving) AKI among ARDS patients on IMV was about 35% (vs 20% subphenotype 1 AKI), and it was an independent predictor of mortality. The DRONE score ≥4 can predict the AKI subphenotype 2.

Highlights

The serum creatinine trajectory-based subphenotype of AKI (resolving vs non-resolving) determines survival in ARDS patients. Non-resolving AKI subphenotype 2 is an independent predictor of mortality in ARDS. The novel DRONE score (driving pressure, oxygenation, and nutritional evaluation) ≥ 4 within 48 hours of IMV predicted the AKI subphenotype 2 among ventilated ARDS patients.

How to cite this article

Todur P, Nileshwar A, Chaudhuri S, Srinivas T. Incidence, Outcomes, and Predictors of Subphenotypes of Acute Kidney Injury among Acute Respiratory Distress Syndrome Patients: A Prospective Observational Study. Indian J Crit Care Med 2023;27(10):724-731.

Kidney-lung Crosstalk in Determining the Prognosis of Acute Kidney Injury Phenotypes in Acute Respiratory Distress Syndrome Patients

How to cite this article: Banerjee T, Bose P. Kidney-lung Crosstalk in Determining the Prognosis of Acute Kidney Injury Phenotypes in Acute Respiratory Distress Syndrome Patients. Indian J Crit Care Med 2023;27(10):701-703.

Development of a predictive nomogram for acute respiratory distress syndrome in patients with acute pancreatitis complicated with acute kidney injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a common complication in patients with acute pancreatitis (AP), especially when patients complicated with acute kidney injury (AKI), resulting in increased duration of hospitalization and mortality. It is of potential clinical significance to develop a predictive model to identify the the high-risk patients.

METHOD

AP patients complicated with AKI from January 2019 to March 2022 were enrolled in this study and randomly divided into training cohort and validation cohort at a ratio of 2:1. The Least absolute shrinkage and selection operator(LASSO) regression and machine learning algorithms were applied to select features. A nomogram was developed based on the multivariate logistic regression. The performance of the nomogram was evaluated by AUC, calibration curves, and decision curve analysis.

RESULTS

A total of 292 patients were enrolled in the study, with 206 in the training cohort and 86 in the validation cohort. Multivariate logistic analysis showed that IAP (Odds Ratio (OR)=4.60, 95%CI:1.23-18.24, p = 0.02), shock (OR = 12.99, 95%CI:3.47-64.04, p < 0.001), CRP(OR= 26.19, 95%CI:9.37-85.57, p < 0.001), LDH (OR = 13.13, 95%CI:4.76-40.42, p < 0.001) were independent predictors of ARDS. The nomogram was developed based on IAP, shock, CRP and LDH. The nomogram showed good discriminative ability with an AUC value of 0.954 and 0.995 in the training and validation cohort, respectively. The calibration curve indicating good concordance between the predicted and observed values. The DCA showed favorable net clinical benefit.

CONCLUSION

This study developed a simple model for predicting ARDS in AP patients complicated with AKI. The nomogram can help clinicians identify high-risk patients and optimize therapeutic strategies.

Rationale and Design of NEUTRALIZE-AKI: A Multicenter, Randomized, Controlled, Pivotal Study to Assess the Safety and Efficacy of a Selective Cytopheretic Device in Patients with Acute Kidney Injury Requiring Continuous Kidney Replacement Therapy

INTRODUCTION

NEUTRALIZE-AKI is a pivotal study to evaluate the safety and effectiveness of the selective cytopheretic device (SCD) in adult patients with acute kidney injury (AKI) requiring continuous kidney replacement therapy (CKRT).

METHODS/DESIGN

This is a two-arm, randomized, open-label, controlled multi-center pivotal US study which will enroll 200 adult patients (age 18-80 years) in the intensive care unit with acute kidney injury requiring CKRT and at least one additional organ failure across 30 clinical centers. Eligible patients will be randomized to CKRT plus SCD therapy versus CKRT alone. Therapy will be administered for up to 10 days, with the hypothesis that the CKRT plus SCD group will demonstrate a lower mortality rate or better rate of renal recovery than the CKRT alone group by day 90. The primary outcome is a composite of dialysis dependence or all-cause mortality at day 90.

CONCLUSION

The SCD is a cell-directed extracorporeal therapy that targets and deactivates pro-inflammatory neutrophils and monocytes, with evidence of efficacy across a variety of critically ill patient populations. Knowledge and experience from many of those studies and other AKI trials were incorporated into the design of this pivotal study, with the aim to investigate the role of effector cell immunomodulation in the intervention of AKI.

Impaired microvascular circulation in distant organs following renal ischemia

Mortality in acute kidney injury (AKI) patients remains very high, although very important advances in understanding the pathophysiology and in diagnosis and supportive care have been made. Most commonly, adverse outcomes are related to extra-renal organ dysfunction and failure. We and others have documented inflammation in remote organs as well as microvascular dysfunction in the kidney after renal ischemia. We hypothesized that abnormal microvascular flow in AKI extends to distant organs. To test this hypothesis, we employed intravital multiphoton fluorescence imaging in a well-characterized rat model of renal ischemia/reperfusion. Marked abnormalities in microvascular flow were seen in every organ evaluated, with decreases up to 46% observed 48 hours postischemia (as compared to sham surgery, p = 0.002). Decreased microvascular plasma flow was found in areas of erythrocyte aggregation and leukocyte adherence to endothelia. Intravital microscopy allowed the characterization of the erythrocyte formations as rouleaux that flowed as one-dimensional aggregates. Observed microvascular abnormalities were associated with significantly elevated fibrinogen levels. Plasma flow within capillaries as well as microthrombi, but not adherent leukocytes, were significantly improved by treatment with the platelet aggregation inhibitor dipyridamole. These microvascular defects may, in part, explain known distant organ dysfunction associated with renal ischemia. The results of these studies are relevant to human acute kidney injury.

A Review of Pathology and Analysis of Approaches to Easing Kidney Disease Impact: Host-Pathogen Communication and Biomedical Visualization Perspective : Advanced Microscopy and Visualization of Host-Pathogen Communication

INTRODUCTION

In addition to affecting the upper respiratory tract, severe acute respiratory syndrome-coronavirus (SARS-CoV) and SARS-CoV-2) can target kidneys resulting in disease impact. There is a lack of effective treatment for SARs-CoV and SARS-CoV-2, and so one approach could be to consider to lower the probable risk and onset of disease amongst immunocompromised and immunosuppressed individuals and patients. Angiotensin Converting Enzyme 2 (ACE2) has a promising impact including acting against SARs-CoV and SARS-CoV-2 symptoms. Current literature states that ACE2 is expressed across several physiological systems, including the lungs, cardiovascular, gut, kidneys, and central nervous, and across endothelia.

AIMS

This chapter seeks to investigate causes and potential mechanisms during SARS infection (CoV-2), renal interaction, and the effects of acute kidney Injury (AKI).

OBJECTIVES

This chapter will provide an overview of microscopy and visualization of host-pathogen communication and principles of ACE2 in the context of immunology and impact on renal pathophysiology.

DESIGN

This chapter focuses to provide basic principles of ACE2 and the analysis and effect of immunology and pathological components important in relation to SARs infection.

DISCUSSION

There has been a surge in literature surrounding mechanisms attributing to SARS-CoV and SARS-CoV-2 action on immune response to pathogens. There is an advantage to implementing ACE2 treatment to improve immune response against infection.

CONCLUSION

ACE2 may provide appropriate strategies for the management of symptoms that relate to SARS-CoV and SARS-CoV-2 in most immunocompromised or immunosuppressed patients. Visualization of ACE2 action can be achieved through microscopy to understand host-pathogen communication.

Overview of the Medical Management of the Critically Ill Patient

The medical management of the critically ill patient focuses predominantly on treatment of the underlying condition (e g, sepsis or respiratory failure). However, in the past decade, the importance of initiating early prophylactic treatment for complications arising from care in the intensive care unit setting has become increasingly apparent. As survival from critical illness has improved, there is an increased prevalence of postintensive care syndrome-defined as a decline in physical, cognitive, or psychologic function among survivors of critical illness. The Intensive Care Unit Liberation Bundle, a major initiative of the Society of Critical Care Medicine, is centered on facilitating the return to normal function as early as possible, with the intent of minimizing iatrogenic harm during necessary critical care. These concepts are universally applicable to patients seen by nephrologists in the intensive care unit and may have particular relevance for patients with kidney failure either on dialysis or after kidney transplant. In this article, we will briefly summarize some known organ-based consequences associated with critical illness, review the components of the ABCDEF bundle (the conceptual framework for Intensive Care Unit Liberation), highlight the role nephrologists can play in implementing and complying with the ABCDEF bundle, and briefly discuss areas for additional research.

Comparison of Clinical Characteristics and Predictors of Mortality between Direct and Indirect ARDS

Background and Objectives: Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous syndrome that encompasses lung injury from a direct pulmonary or indirect systemic insult. Studies have shown that direct and indirect ARDS differ in their pathophysiologic process. In this study, we aimed to compare the different clinical characteristics and predictors of 28-day mortality between direct and indirect ARDS. Materials and Methods: The data of 1291 ARDS patients from September 2012 to December 2021 at the Second Affiliated Hospital of Chongqing Medical University were reviewed. We enrolled 451 ARDS patients in our study through inclusion and exclusion criteria. According to the risk factors, each patient was divided into direct (n = 239) or indirect (n = 212) ARDS groups. The primary outcome was 28-day mortality. Results: The patients with direct ARDS were more likely to be older (p < 0.001) and male (p = 0.009) and have more comorbidity (p < 0.05) and higher 28-day mortality (p < 0.001) than those with indirect ARDS. Age and multiple organ dysfunction syndrome (MODS) were predictors of 28-day mortality in the direct ARDS group, while age, MODS, creatinine, prothrombin time (PT), and oxygenation index (OI) were independent predictors of 28-day mortality in the indirect ARDS group. Creatinine, PT, and OI have interactions with ARDS types (all p < 0.01). Conclusions: The patients with direct ARDS were more likely to be older and male and have worse conditions and prognoses than those with indirect ARDS. Creatinine, PT, and OI were predictors of 28-day mortality only in the indirect ARDS group. The differences between direct and indirect ARDS suggest the need for different management strategies of ARDS.