Daily Ards Research Analysis
A UK multicenter pragmatic RCT (REST) found no mortality or long-term benefit of extracorporeal CO2 removal (ECCO2R) for acute hypoxemic respiratory failure, with higher costs and potential complications. A prospective physiologic cohort showed that ARDS nonsurvivors spend substantially more time at high respiratory effort and high dynamic transpulmonary driving pressure during spontaneous breathing. A comprehensive scoping review found no conclusive advantage of spontaneous versus controlled ve
Summary
A UK multicenter pragmatic RCT (REST) found no mortality or long-term benefit of extracorporeal CO2 removal (ECCO2R) for acute hypoxemic respiratory failure, with higher costs and potential complications. A prospective physiologic cohort showed that ARDS nonsurvivors spend substantially more time at high respiratory effort and high dynamic transpulmonary driving pressure during spontaneous breathing. A comprehensive scoping review found no conclusive advantage of spontaneous versus controlled ventilation in ARDS and highlighted major evidence gaps, especially in long-term patient-reported outcomes.
Research Themes
- Ventilator strategy and patient effort in ARDS
- Extracorporeal support in acute hypoxemic respiratory failure
- Evidence synthesis and research gaps in ARDS management
Selected Articles
1. Extracorporeal carbon dioxide removal for the treatment of acute hypoxaemic respiratory failure: the REST RCT.
In this UK multicenter pragmatic RCT (n=412), ECCO2R-facilitated lower tidal volume ventilation did not reduce 90-day mortality versus standard care (41.5% vs 39.5%; RR 1.05, 95% CI 0.83–1.33) and conferred no short- or long-term benefits. The device increased costs and had potential complications; the trial was stopped early for futility, and routine use outside trials is discouraged.
Impact: A high-quality randomized trial provides definitive negative evidence against ECCO2R for hypoxemic respiratory failure/ARDS, guiding de-implementation and resource allocation.
Clinical Implications: Do not adopt ECCO2R in routine care for hypoxemic respiratory failure/ARDS; prioritize conventional lung-protective ventilation and consider ECCO2R only within clinical trials.
Key Findings
- No reduction in 90-day mortality with ECCO2R vs standard care (41.5% vs 39.5%; RR 1.05, 95% CI 0.83–1.33).
- No short- or long-term benefits in secondary outcomes; higher costs and potential device-related complications.
- Trial stopped early for futility; only 6% of screened patients enrolled, and sites were largely intervention-naïve.
Methodological Strengths
- Multicenter, allocation-concealed, pragmatic RCT with health-economic and long-term outcomes.
- Clear primary endpoint (90-day mortality) and predefined stopping rules.
Limitations
- Early termination reduced power; open-label design and heterogeneity in usual care.
- Low enrollment proportion (6%) and site inexperience with the intervention may affect generalizability.
Future Directions: Explore targeted subgroups or higher 'dose' ECCO2R strategies within trials, adopt core outcome sets, and collect early patient-reported quality-of-life metrics.
BACKGROUND: In patients who require mechanical ventilation for acute hypoxaemic respiratory failure, further reduction in tidal volumes, compared with conventional low tidal volume ventilation, may improve outcomes. OBJECTIVE: To determine whether using extracorporeal carbon dioxide removal improves outcomes in patients with acute hypoxaemic respiratory failure and is cost-effective. DESIGN: A multicentre, randomised, allocation-concealed, open-label, pragmatic clinical trial. SETTING: Fifty-one intensive care units across the United Kingdom. PARTICIPANTS: Four hundred and tw
2. Association of Breathing Effort With Survival in Patients With Acute Respiratory Distress Syndrome.
In a prospective physiologic cohort with continuous monitoring over 7 days of spontaneous breathing, nonsurvivors (n=7) spent more time at high effort (12% vs 3%) and at high dynamic transpulmonary driving pressure (>25 cm H2O: 74% vs 32%) compared with survivors. Survivors spent more time in the moderate effort range.
Impact: Provides time-resolved evidence linking excessive respiratory effort and high transpulmonary driving pressure exposure to mortality, reinforcing the concept of patient self-inflicted lung injury.
Clinical Implications: Consider monitoring respiratory effort (e.g., esophageal pressure) and minimizing prolonged high-effort exposure through sedation titration, ventilator adjustments, and mode selection to limit dynamic transpulmonary driving pressure.
Key Findings
- Analyzed 1,485,405 respiratory cycles from 26 ARDS patients over 7 days of spontaneous breathing.
- Nonsurvivors spent more time in high effort (12% vs 3%; p=0.006) and less in moderate effort (5% vs 50%; p<0.001).
- Exposure to high dynamic transpulmonary driving pressure (>25 cm H2O) was greater in nonsurvivors (74% vs 32%; p=0.001).
Methodological Strengths
- Prospective continuous physiological monitoring with esophageal and gastric pressure measurements.
- Pre-registered study and variance-weighted analyses accounting for cycle-level variability.
Limitations
- Small sample size (n=26) limits generalizability and precision.
- Observational design cannot establish causality; specialized monitoring may limit feasibility.
Future Directions: Randomized trials targeting effort reduction thresholds and pragmatic strategies to limit high dynamic transpulmonary driving pressure; develop feasible bedside surrogates of effort.
OBJECTIVES: Invasive mechanical ventilation (IMV) is crucial for acute respiratory distress syndrome (ARDS) management, but mortality remains high. While spontaneous breathing is key to weaning, excessive respiratory effort may injure the lung and diaphragm. Most existing data on respiratory effort during IMV are based on brief periods of observation, potentially underestimating the burden of inappropriate efforts. This study aims to characterize the evolution of respiratory effort over time in ARDS patients and its relation to survival. We hypothesized that nonsurvivors would spend a greater proportion of time in the high-effort range during the active breathing phase compared with survivors. DESIGN, SETTING, AND PATIENTS: In this prospective cohort study, we continuously recorded airway pressure, flow, esophageal, and gastric pressures in ARDS patients on mechanical ventilation during 7 days after the onset of spontaneous breathing. We analyzed physiologic respiratory effort variables, focusing on the proportion of time spent within defined effort ranges, and compared these data between ICU survivors and nonsurvivors. Statistical analysis was conducted using variance weighted methods to account for variability in the number of respiratory cycles analyzed per patient. This study is registered at ClinicalTrials.gov under identifier NCT06490523. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 1,485,405 respiratory cycles were analyzed from 26 ARDS patients (19 survivors, seven nonsurvivors). Nonsurvivors spent significantly more time in high effort (12% vs. 3%; p = 0.006). In contrast, survivors spent more time in the moderate-effort range (50% vs. 5%; p < 0.001). The time spend with high dynamic transpulmonary driving pressure (> 25 cm H 2 O) was also significantly different between groups (32% survivors vs. 74% nonsurvivors; p = 0.001). CONCLUSIONS: Patients who die of ARDS are more likely to be exposed to high respiratory effort for prolonged periods of time compared with survivors.
3. Spontaneous Versus Controlled Mechanical Ventilation in Patients With Acute Respiratory Distress Syndrome-A Scoping Review.
This PRISMA-compliant scoping review included 564 studies (114 trials, 267 observational) comparing assisted/spontaneous versus controlled ventilation in ARDS and found no conclusive advantage of either strategy. Long-term, patient-reported outcomes were rarely captured, underscoring key gaps for future trials.
Impact: Provides the most comprehensive mapping to date of spontaneous versus controlled ventilation in ARDS and highlights critical methodological and outcome-reporting gaps.
Clinical Implications: No ventilatory strategy is clearly superior; clinicians should individualize ventilation and consistently apply lung-protective principles while awaiting definitive trials that include patient-centered outcomes.
Key Findings
- Included 564 studies: 114 clinical trials and 267 observational studies across invasive and non-invasive ventilation.
- No conclusive evidence favoring spontaneous/assisted breathing over controlled ventilation, or vice versa.
- Long-term patient-reported outcomes were rarely reported, marking a major research gap.
Methodological Strengths
- PRISMA-ScR compliant methodology with broad database coverage (PubMed, CINAHL, Embase, Cochrane).
- Use of GRADE and meta-analyses when appropriate to summarize evidence.
Limitations
- Scoping design precludes definitive effect estimates; high heterogeneity across studies.
- Inclusion of abstracts and mixed-quality evidence may introduce bias; not focused on patient-reported outcomes.
Future Directions: Design adequately powered RCTs comparing ventilatory strategies with standardized protocols, incorporate patient-reported long-term outcomes, and define effort/pressure thresholds.
BACKGROUND: Mechanically ventilated patients with acute respiratory distress syndrome (ARDS) can be managed using either controlled or spontaneous (assisted) breathing modes. While both approaches are used in clinical practice, the proportion of patients receiving mechanical ventilation that allows for spontaneous breaths and the impact of this strategy on patient outcomes remain unclear. This scoping review aimed to map and summarise the scope, range and nature of the evidence for assisted versus controlled breathing in mechanically ventilated patients with ARDS, including identification of research gaps. METHODS: We conducted a scoping review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews. We searched PubMed, CINAHL, Embase and the Cochrane Library for literature on controlled versus spontaneous breathing in mechanically ventilated patients with ARDS, irrespective of severity. Studies reporting qualitative and/or quantitative data from any world region were included. Where relevant, we performed meta-analyses to summarise data, and we assessed the overall quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. RESULTS: Our search was completed on May 13, 2025. We identified 6827 titles, with 1193 studies assessed in full text. A total of 564 studies were included in the final review, comprising 114 clinical trials, 267 observational studies, as well as case reports, conference abstracts and surveys. Both invasive and non-invasive ventilation techniques were described. Patient-important outcomes were limited to short- and long-term survival, duration of mechanical ventilation, length of stay and complications (e.g., pneumothorax). Patient-reported long-term outcomes were rarely reported. The evidence does not conclusively favour either spontaneous or controlled mechanical ventilation. CONCLUSION: Our scoping review identifies extensive documentation of widespread use of spontaneous breathing techniques, with both invasive and non-invasive ventilation, in patients with ARDS. Despite data from several large observational studies and one large randomised clinical trial, the benefits and harms of spontaneous versus controlled ventilation remain unclear. The near absence of long-term, patient-reported outcomes defines an important research gap. EDITORIAL COMMENT: This systematic review addresses current evidence concerning whether or not spontaneous ventilation with support or assistance is more advantageous for critically ill ventilator-dependent ARDS cases versus passive positive pressure ventilatory support. To distinguish and separate these 2 approaches in critical care treatment is challenging, and this review nicely presents the current state of evidence for this field, including knowledge gaps.