Spontaneous Versus Controlled Mechanical Ventilation in Patients With Acute Respiratory Distress Syndrome-A Scoping Review

Abstract

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.