Electrical impedance tomography reveals pathophysiology of neonatal pneumothorax during NAVA

Abstract

Pneumothorax is a potentially life-threatening complication of neonatal respiratory distress syndrome (RDS). We describe a case of a tension pneumothorax that occurred during neurally adjusted ventilatory assist (NAVA) in a preterm infant suffering from RDS. The infant was included in a multicenter study examining the role of electrical impedance tomography (EIT) in intensive care and therefore continuously monitored with this imaging method. The attending physicians were blinded for EIT findings but offline analysis revealed the potential of EIT to clarify the underlying cause of this complication, which in this case was heterogeneous lung disease resulting in uneven ventilation distribution. Instantaneous increase in end-expiratory lung impedance on the affected side was observed at time of the air leak. Real-time bedside availability of EIT data could have modified the treatment decisions made.

Keywords: electrical impedance tomography (EIT); neonate; neurally adjusted ventilatory assist; pneumothorax; respiratory distress syndrome (RDS).

Figure 1

Chest X‐rays (CXR) taken during the case study with corresponding EIT findings at the same time points. A, Correct positions of the endotracheal tube and nasogastric tube were confirmed. B, Right‐sided tension pneumothorax was observed. C, Right‐sided pneumothorax remained until the end of EIT recording and insertion of a chest tube. D‐F, Relative distribution of ventilation between the right and left chest sides based on tidal impedance variation (ΔZ). G‐I, Changes in regional aeration at the right and left chest sides in arbitrary units (AU). The values show differences in end‐expiratory lung impedance (EELZ) compared with the respective values before intubation. Positive values imply aeration increase

Figure 2

Electrical impedance tomography data, oxygenation and ventilator parameters during the case study. A, Composite electrical impedance tomography (EIT) signal in arbitrary units (AU) for left (blue) and right (orange) chest sides are presented. The level of each curve reflects the regional aeration in terms of end‐expiratory lung impedance (EELZ) and the amplitude of the curve the regional tidal volumes in terms of tidal impedance variation (∆Z) at each point in time. Postnatal age of the patient is presented on the X axis. The exact time points of selected interventions are marked with arrows. Gray background highlights the time on NAVA, white on PCV. B, Changes in oxygenation over time. Fraction of inspired oxygen (FiO₂) in orange, peripheral oxygen saturation/fraction of inspired oxygen (SF) ratio in blue. C, Airway pressures over time. Peak inspiratory pressure (PIP) in blue, mean airway pressure (M_PAW) in orange and positive end‐expiratory pressure (PEEP) in yellow. D, Inspiratory (V_Ti) in blue and expiratory (V_Te) tidal volumes in red over time. E, Dynamic respiratory system compliance (C_rs) derived from the airway pressures and tidal volumes