Abstract
Acute respiratory distress syndrome (ARDS) is a heterogeneous group of disease entities that are associated with acute hypoxic respiratory failure and significant morbidity and mortality. With a better understanding and phenotyping of lung injury, novel pathophysiologic mechanisms demonstrate the impact of a patient’s excessive spontaneous breathing effort on perpetuating lung injury. Patient self-inflicted lung injury (P-SILI) is a recently identified phenomenon that delves into the impact of spontaneous breathing on respiratory mechanics in patients with lung injury. While the studies are hypothesis-generating and have been demonstrated in animal and human studies, further clinical trials are needed to identify its impact on ARDS management. The purpose of this review article is to highlight the physiologic mechanisms of P-SILI, novel tools and methods to detect P-SILI, and to review the current literature on non-invasive and invasive respiratory management in patients with ARDS.
Key Points
- P-SILI and ARDS Progression: P-SILI occurs due to excessive spontaneous breathing efforts, increasing stress and strain on injured lungs, and exacerbating existing damage before mechanical ventilation is initiated.
- Stress, Strain, and Overdistension: High transpulmonary pressures (PL) and strain can lead to alveolar overdistension, which accelerates lung injury and contributes to the worsening of ARDS.
- Pendelluft and Heterogeneous Ventilation: Uneven pressure distribution during spontaneous breathing can result in pendelluft, where air shifts from non-dependent to dependent lung regions, causing regional overdistension and worsening lung injury.
- Microvascular Injury and Pulmonary Edema: High inspiratory effort can increase transvascular pressures, leading to microvascular injury and negative pressure pulmonary edema, further impairing oxygenation.
- Patient-Ventilator Dyssynchrony: Strong inspiratory efforts during mechanical ventilation can lead to breath stacking and excessive tidal volumes, increasing the risk of ventilator-induced lung injury (VILI).
- Novel Monitoring Techniques for P-SILI: Esophageal manometry, electrical impedance tomography (EIT), and diaphragm electrical activity (EAdi) monitoring are emerging tools to assess spontaneous breathing effort and lung stress.
- PEEP Optimization and ARDS Management: While higher PEEP can mitigate pendelluft and reduce inspiratory effort, it must be tailored to avoid overdistension and right ventricular strain.
- Non-Invasive Respiratory Support and P-SILI Prevention: High-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) may reduce the risk of P-SILI but require close monitoring using validated scoring tools such as the ROX index and HACOR score.
- Lung Protective Strategies in IMV: Driving pressure (DP) and transpulmonary pressure (PL) should be minimized to prevent P-SILI. Neuromuscular blockade (NMB) can be considered in patients with severe ARDS to limit excessive spontaneous effort.
- Future Directions in P-SILI Research: Further studies are needed to refine P-SILI identification, assess its prognostic implications, and develop personalized ventilation strategies based on real-time respiratory monitoring.
