Estimation of changes in cyclic lung strain by electrical impedance tomography: Proof‐of‐concept study

Abstract

Rationale: Cyclic strain may be a determinant of ventilator-induced lung injury. The standard for strain assessment is the computed tomography (CT), which does not allow continuous monitoring and exposes to radiation. Electrical impedance tomography (EIT) is able to monitor changes in regional lung ventilation. In addition, there is a correlation between mechanical deformation of materials and detectable changes in its electrical impedance, making EIT a potential surrogate for cyclic lung strain measured by CT (Strain CT ).Objectives: To compare the global Strain CT with the change in electrical impedance (ΔZ).Methods: Acute respiratory distress syndrome patients under mechanical ventilation (V T 6 mL/kg ideal body weight with positive end-expiratory pressure 5 [PEEP 5] and best PEEP according to EIT) underwent whole-lung CT at end-inspiration and end-expiration. Biomechanical analysis was used to construct 3D maps and determine Strain CT at different levels of PEEP. CT and EIT acquisitions were performed simultaneously. Multilevel analysis was employed to determine the causal association between Strain CT and ΔZ. Linear regression models were used to predict the change in lung Strain CT between different PEEP levels based on the change in ΔZ.Main results: Strain CT was positively and independently associated with ΔZ at global level (P < .01). Furthermore, the change in Strain CT (between PEEP 5 and Best PEEP) was accurately predicted by the change in ΔZ (R 2 0.855, P < .001 at global level) with a high agreement between predicted and measured Strain CT . Conclusions:The change in electrical impedance may provide a noninvasive assessment of global cyclic strain, without radiation at bedside. | 229 CORNEJO Et al.

Electrical impedance tomography-guided positive end-expiratory pressure titration in ARDS: a systematic review and meta-analysis

“…As such, the capacity of EIT to visualize ventilation distribution within distinct lung regions facilitates data-driven insights into PEEP titration and ventilator management. Specifically, EIT enables quantification of lung inhomogeneity, analysis of regional and global ventilation patterns, and identification of potentially recruitable lung areas [ 31 , 51 , 52 ].…”

Pendelluft in hypoxemic patients resuming spontaneous breathing: proportional modes versus pressure support ventilation

“…This was a clinical–physiological crossover study and we compared pendelluft magnitude in NAVA and PAV + versus PSV. An individualized level of positive end-expiratory pressure (PEEP) was set considering the lowest combination of collapse and overdistension according to EIT monitoring [ 14 , 15 ].…”

Involvement of the Lung Parenchyma Analyzed by Frequency Components of the Tidal Volume Assessed by Electrical Bioimpedance

“…EIT frames are reconstructed from a set of impedance measurements obtained by an arrangement of 16 electrodes placed around the thorax at the level of the sixth intercostal space [9][10] [11] , registering impedance changes that allow the characterization of internal movements produced by the human body. Some EIT applications in pneumology include: 1) estimation of regional lung perfusion [12] [13] , 2) regional lung ventilation characterization in patients with pulmonary fibrosis [14] and pulmonary hypertension [15] , 3) detection of bronchopulmonary dysplasia in neonates at early stages [16] , 4) ventilatory pattern monitoring in patients diagnosed with sudden onset of respiratory distress syndrome (ARDS) [17] , 5) evaluation of an effect of pleural effusion drainage in patients submitted to mechanical ventilation [18] , among others.…”