External Validation of the BREF Models

Introduction High-flow oxygen therapy is increasingly used to treat acute respiratory failure (ARF). It can reduce intubation rates without increasing mortality. Moreover, it is better tolerated than other non-invasive respiratory support therapies. However, patients with ARF often make strong breathing efforts, which may cause several harm. They can fatigue the respiratory muscles. They can increase whole-body oxygen consumption and carbon dioxide production. They can cause pulmonary edema. They might also injure the diaphragm and the lungs. For all these reasons, strong breathing efforts should be recognized and treated. During spontaneous breathing, inspiratory muscle contractions produce parallel deflections of the pleural and esophageal pressure (ΔPes), which reflect the magnitude of the effort. Unlike changes in pleural pressure, ΔPes can be easily measured at the bedside using a