Comparing ventilation modes by electrical impedance segmentography in ventilated children

Abstract

Electrical impedance segmentography offers a new radiation-free possibility of continuous bedside ventilation monitoring. The aim of this study was to evaluate the efficacy and reproducibility of this bedside tool by comparing synchronized intermittent mandatory ventilation (SIMV) with neurally adjusted ventilatory assist (NAVA) in critically-ill children. In this prospective randomized case-control crossover trial in a pediatric intensive care unit of a tertiary center, including eight mechanically-ventilated children, four sequences of two different ventilation modes were consecutively applied. All children were randomized into two groups; starting on NAVA or SIMV. During ventilation, electric impedance segmentography measurements were recorded. The relative difference of vertical impedance between both ventilatory modes was measured (median 0.52, IQR 0-0.87). These differences in left apical lung segments were present during the first (median 0.58, IQR 0-0.89, p = 0.04) and second crossover (median 0.50, IQR 0-0.88, p = 0.05) as well as across total impedance (0.52 IQR 0-0.87; p = 0.002). During NAVA children showed a shift of impedance towards caudal lung segments, compared to SIMV. Electrical impedance segmentography enables dynamic monitoring of transthoracic impedance. The immediate benefit of personalized ventilatory strategies can be seen when using this simple-to-apply bedside tool for measuring lung impedance.

Keywords: Bedside monitoring; Dependent lung area; Electrical Impedance Segmentography; NAVA; Pediatric ventilation; Personalized ventilation.

Fig. 1

Measuring area of butterfly and single electrodes. On the left, a butterfly electrode placed over the sternum is depicted. The measuring area of single electrodes is depicted on the right. Both depictions are subdivided into the respective four quadrants of measurement. Since single electrodes were used in recently-thoracotomized children, the central electrode was placed on the left side of the thoracotomy site

Fig. 2

Cumulative and singular total impedance shift depending on the applied breathing method. Median ± IQR of the relative difference between measured impedance during NAVA and SIMV (PC) PS

Fig. 3

Cumulative and singular impedance shift of the percentage of the left segments depending on the applied ventilatory mode. Median ± IQR of the relative difference between NAVA and SIMV (PC) PS

Fig. 4

Cumulative and singular impedance shift of the percentage of the upper segments depending on the applied ventilatory mode