This study evaluates changes in regional lung ventilation using thoracic electrical impedance tomography (EIT) during the weaning process from mechanical ventilation in ICU patients with acute brain injury. It aims to identify predictive EIT patterns related to extubation outcomes.
This is a prospective, single-center pilot study conducted in the intensive care unit. The study focuses on adult patients with acute brain injury requiring invasive mechanical ventilation for more than 48 hours. The aim is to assess regional alveolar ventilation using thoracic electrical impedance tomography (EIT) during different stages of ventilator weaning, including changes in ventilatory mode, spontaneous breathing trials, and, when feasible, around extubation or decannulation. EIT provides dynamic, non-invasive real-time imaging of regional pulmonary ventilation. Data will be collected using a 16-electrode thoracic belt and analyzed retrospectively with dedicated software. The primary outcome measure is the Absolute Ventral-to-Dorsal Ventilation Difference, calculated from predefined regions of interest. Secondary outcomes include correlations with traditional ventilatory parameters (tidal volume, respiratory rate, oxygen saturation), end-expiratory impedance variation (ΔEELI), compliance changes, and extubation or decannulation failure defined by the need for reintubation within 7 days. This study aims to improve understanding of regional ventilation patterns in brain-injured patients and assess the potential of EIT to predict weaning outcomes and guide personalized ventilatory strategies.
Study Type
OBSERVATIONAL
Enrollment
60
Internal Thoracic Impedance is a non-invasive an imaging technique which use low alternative current through electrodes placed on a belt positioned at the level of the patient's rib cage. Images are constructed according to conductivity measured.
Hôpital Lariboisière - APHP
Paris, France, France
Absolute ventral-to-dorsal ventilation difference
The Absolute V-D Difference will be calculated as the average of the ventilation in the ventral regions (ROI1 and ROI2) minus the average of the ventilation in the dorsal regions (ROI3 and ROI4) during mechanical ventilation weaning. This outcome will provide insights into regional pulmonary ventilation distribution and its correlation with extubation outcomes. This difference is calculated as follows: (ROI\_Value1 + ROI\_Value2)/2 - (ROI\_Value3 + ROI\_Value4)/2 expressed as a percentage.
Time frame: From the start of the ventilator mode change or spontaneous breathing trial until 30 minutes after.
Correlation between Absolute V-D Difference and Conventional Ventilatory Parameters
This outcome will evaluate how the Absolute V-D Difference correlates with other monitoring parameters, such as tidal volume, respiratory rate, SpO₂, and end-tidal CO₂ (EtCO₂), throughout the weaning process.
Time frame: From the start of the ventilator mode change or spontaneous breathing trial until 30 minutes after
End-Expiratory Lung Impedance (ΔEELI)
The monitoring of ΔEELI will be continuous throughout the spontaneous breathing trial, which lasts 30 minutes. Monitoring will begin at a stable baseline 5 minutes prior to the start of the trial and will continue until 5 minutes after its completion. Three specific time points will be collected and analyzed: 1. EELI before the trial (baseline, 5 minutes prior), 2. EELI at the end of the trial (30 minutes), 3. EELI 5 minutes after resumption of mechanical ventilation
Time frame: From 5 minutes before to 5 minutes after the 30-minute spontaneous breathing trial (i.e., total duration of 40 minutes)
Correlation between ΔEELI and Extubation/Decannulation Failure
This secondary outcome assesses the relationship between changes in end-expiratory impedance (ΔEELI) and extubation or decannulation failure, defined as reintubation or need for reventilation within 7 days.
Time frame: 7 days post-extubation or post-deventilation.
Pulmonary Compliance Variation during Ventilator Changes and Spontaneous Breathing Trials
This measure will track the changes in regional pulmonary compliance in response to adjustments in ventilator parameters (e.g., PEEP, tidal volume) and spontaneous breathing trials.
Time frame: From the start of ventilator mode change or spontaneous breathing trial until 30 minutes after.
Absolute V-D Difference and Extubation Failure
This outcome will examine the correlation between the Absolute V-D Difference and extubation failure, defined as reintubation or the need for reventilation within 7 days post-extubation or post-deventilation.
Time frame: 7 days post-extubation or post-deventilation.
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