Effect of sternal electrode gap and belt rotation on the robustness of pulmonary electrical impedance tomography parameters

Abstract

Objective: Non-adhesive textile electrode belts offer several advantages over adhesive electrodes and are increasingly used in neonatal patients during continuous electrical impedance tomography (EIT) lung monitoring. However, non-adhesive belts may rotate in unsedated patients and discrepancies between chest circumference and belt sizes may result in a gap between electrodes near the sternum. This project aimed to determine the effects of belt rotation and sternal electrode gap on commonly used lung EIT parameters. Approach: We developed a simulation framework based on a three-dimensional finiteelement model and introduced lung regions with little or no ventilation that could be changed according to a decremental positive end-expiratory pressure (PEEP) trial. Four degrees of sternal gap and belt rotation were simulated and their effect on the EIT parameters silent spaces, centre of ventilation, global inhomogeneity index and overdistension/collapsed lung (OD/CL) analysed. Additionally, seven premature infants were examined to assess the influence of leftward and rightward belt rotations in a clinical setting. Main results: Small violations of the electrode equidistance criterion and rotations of the belts less than one electrode space exert only minor effects on the EIT parameters and do not impede the interpretation. Rotations of two and three electrode spaces induce nonnegligible effects that might lead to flawed interpretations. The "best PEEP" determined with the OD/CL approach was robust and identifiable with all studied sternal gaps and belt rotations.Significance: We revealed an important challenge for neonatal EIT applications related to a wide electrode gap at the sternum and belt rotation, which should be avoided in clinical application.

Regional ventilation characteristics during non-invasive respiratory support in preterm infants

“…[10,31,37] Current neonatal EIT systems now have real-time processing and simple non-adhesive belts that can be applied during multiple scenarios, and for prolonged periods. [16,38] EIT has already been proposed as a simple radiation-free method of determining endotracheal tube location and air-leaks. [11,39,40] The observation that gravity-dependent V T inhomogeneity differed between infants that developed BPD and those that did not is intriguing.…”

Model Selection Based Algorithm in Neonatal Chest EIT

“…The commercially available neonatal EIT belts are not equipped with any mechanism to keep them fixed in their initial position [7] [29]. Hence, in practice they are subject to possible rotation and sliding in the craniocaudal direction as the patient moves [30]. Slight movements of the belt may cause significant variations in internal organ distribution due to the considerably small dimensions of neonates, especially if born premature.…”

Lung Imaging Acquisition with Electrical Impedance Tomography: Tackling Common Pitfalls

“…However, none of the models are planned to account for overlapping electrodes or rotated belts. Belt rotation may happen, especially in the neonatal population, and Sophocleous et al 32 showed that a belt rotation higher than one electrode space significantly altered calculated electrical impedance tomography measurements.…”