Extremes of Respiratory Effort in Weaning Failure From Mechanical Ventilation: a Prospective Observational Study

Introduction: The presence of high levels of respiratory effort in patients under mechanical ventilation may worsen the adjacent lung injury even after adapting protective ventilation, potentially prolonging the MV period. Primary outcome: To evaluate the failure rate of weaning from IMV and its relationship with the lower and upper extremes of respiratory effort and the upper extreme of dynamic lung stress during the first 7 days of spontaneous ventilation. Secondary outcomes: Analyze the influence of these extremes based on the thresholds of Pocc, P0.1 and their derivatives Pmus, Ptp, din and MP: in relation to days off MV (in the 28-day interval); Total weaning time; Rate and time for tracheostomy; Length of stay in the ICU and hospital; evaluate the variation in ventilation distribution through electrical impedance tomography with the extremes of Pocc and Pmus; analyze the fraction of diaphragmatic thickening and diaphragmatic excursion through diaphragmatic ultrasound at the upper and lower levels of Pocc and Pmus; In-hospital mortality rate. Methodology: CAAE: 78185823.4.0000.5249; Prospective multicenter observational study, carried out in the ICUs of Glória D'or and Niteroi D'or Hospitals, from January 2024 to July 2026, in patients over 18 years old, undergoing orotracheal intubation and IMV, in their first 7 days on spontaneous ventilation, excluding if patients with neuromuscular disease; Phrenic nerve injury; MV for less than 24 hours; Previously tracheostomized patient; Age under 18; Use of neuromuscular blocker > 72h; COPD sufferer; Pregnancy; Patient under palliative care; COVID-19 pneumonia; Patients reintubated after extubation in this hospitalization for less than 3 weeks. Statistical analysis: the sample calculation showed an estimated value of 50 patients for two candidate predictor variables; variables will be reported as mean (SD), median (IQ 25 - 75%) or absolute and relative frequencies. The estimate of any association between variables of upper and lower extremes of effort and dynamic pulmonary stress, as well as the ventilatory parameters used will be evaluated with preliminary univariate analysis (chi-square test with Yates' correction or Fisher's exact test), followed by a model multivariate logistic regression analysis adjusted for all clinical variables at hospital admission. Survival time, as well as hospital admission time until the event, will be analyzed using Kaplan-Meier estimates; the log-rank test will be used to compare groups. Values of p < 0.05 will be considered statistically significant. Hypothesis: Extremes of respiratory effort and dynamic pulmonary stress would be associated with a higher rate of weaning from IMV, as well as longer time on IMV and subsequent longer hospital stay.

Inclusion criteria

• Patients over 18 years old, admitted to the Glória D'or hospital, undergoing orotracheal intubation and invasive mechanical ventilation, in their first 7 years on spontaneous ventilation, who accept to participate in the study by signing the free and informed consent form (or by their legal responsible).

Exclusion criteria

• • Neuromuscular disease;

• Phrenic nerve injury;
• MV for less than 24 hours;
• Previously tracheostomized patient;
• Age under 18;
• Use of neuromuscular blocker > 72h;
• COPD;
• Patients with pulmonary fibrosis;
• Pregnancy;
• Patient under palliative care;
• COVID-19 pneumonia;
• Patients reintubated after extubation in this hospitalization for less than 3 weeks.