Lung perfusion estimation by saline-contrast EIT without breath hold: a randomized cross-over trial

Area of Science:

• Medical Imaging
• Pulmonary Physiology
• Critical Care Medicine

Background:

• Assessing regional lung perfusion in mechanically ventilated ICU patients is crucial.
• Conventional contrast-enhanced electrical impedance tomography (EIT) requires breath-holding, limiting its use.
• Developing a non-breath-holding method is essential for broader clinical application.

Purpose of the Study:

• To develop and validate a non-breath-holding contrast-enhanced EIT method.
• To assess regional lung perfusion at the bedside in mechanically ventilated patients.
• To utilize low-pass filtering to mitigate respiratory interference.

Main Methods:

• A randomized cross-over trial involving 20 mechanically ventilated ICU patients.
• Comparison of contrast-EIT during end-expiratory pause (apnea) versus ongoing mechanical ventilation (non-apnea).
• A 0.17 Hz low-pass filter was applied for the non-apnea method; pixel-wise correlation assessed using Spearman analysis.

Main Results:

• High overall consistency between apnea and non-apnea methods (median r = 0.94).
• Comparable global V/Q match%, dead space%, and shunt% between both methods.
• Significantly shorter impedance drop duration in the non-apnea method (5.3 s vs. 6.1 s).

Conclusions:

• The non-apnea contrast-EIT method yields consistent lung perfusion images compared to the apnea method.
• This technique expands EIT applicability to patients unable to tolerate apnea.
• The non-apnea approach may provide more physiologically realistic perfusion results.