Analysis of Advanced Physiological Ventilatory Parameters During Spontaneous Breathing Effort in Patients with Acute Hypoxemic Respiratory Failure

The aim of this prospective physiological cohort study conducted in a medical intensive care unit (ICU) at Hospital del Mar in Barcelona, Spain, was to analyze the proportion of time spent within the "safe" range of respiratory effort (including esophageal pressure swing (ΔPes), respiratory muscular pressure (Pmus), and transdiaphragmatic pressure swing (ΔPdi)) in patients with acute hypoxemic respiratory failure (AHRF) undergoing invasive mechanical ventilation (IMV), during the active breathing phase in relation to ICU survival. The investigators hypothesized that AHRF patients on IMV with better outcome (i.e., ICU survivors) spend more time within the "safe" range of respiratory effort during the active breathing phase compared to non-survivors. AHRF patients on IMV were continuously monitored with esophageal and gastric manometry from the detection of the onset of respiratory effort for up to 7 days, or until extubation, or until death, whichever occurred first.

To characterize in detail the evolution of respiratory effort over time, the investigators conducted a prospective observational cohort study with continuous recordings of airway pressure, flow, esophageal and gastric pressures for up to 7 days after the onset of respiratory effort in AHRF patients on IMV. Patients were classified into two groups: ICU survivors and ICU non-survivors. The primary objective of the study was to analyze the proportion of time spent within a specified "safe" range for Pmus, ΔPes, and ΔPdi (respiratory effort physiological variables), during spontaneous breathing, comparing both groups during the first 7 days after the initiation of respiratory effort. The secondary objective was to analyze the median values of ΔPes, Pmus, and ΔPdi during the monitorization period (active breathing phase) between the two groups.