Electrical impedance tomography for evaluating child respiratory rehabilitation

A 3-year-old girl had underlying spastic quadriplegia and severe neurological impairment following hypoxic–ischemic encephalopathy. She had severe scoliosis and was unable to turn over in bed, with a Gross Motor Function Classification System grade of Level V. She was treated at bedtime with nasal non-invasive positive pressure ventilation on 8cmH2O continuous positive airway pressure because she had sleep-disordering breathing caused by the narrowing upper and lower airway because of glossoptosis, scoliosis, and flattened thorax. She was hospitalized because of aspiration pneumonia. During her treatment, respiratory physiotherapy was necessary. Electrical impedance tomography (EIT; Enlight 2100, Timpel), which captures and visualizes local gas movement in the lungs, was used to assess rehabilitation effects. As shown by chest computed tomography (CT) (Figure 1a), her spine was convex to the right, compressing the right main bronchi. Additionally, her right lung was collapsed, presumably the result of the locational shift of intrathoracic organs. The patient was laid on her right side to recruit the left collapsed lung. Immediately after the position change, EIT showed that the left lung remained collapsed, but it was recruited gradually (Figure 1b,c). The findings suggested that the right lateral decubitus position was effective for left lung ventilation and also that the improvement of lung ventilation was time dependent. Supine positioning with her preferred neck position (left neck rotation instead of midline) recruited the left lung (Figure 1d). Results show that her preferred position was also beneficial for increasing ventilation in her collapsed left lung. Ventilation of the left ventral lung was not achieved In the sitting position. Good ventilation was obtained by reclining the trunk, such as in a stroller. Her left lung was also recruited in the prone position (Figure 1e). In the same prone position, left lung ventilation was improved further when her upper body was elevated about 10˚ (Figure 1f). However, the improvement in ventilation shown by EIT was presumed to be due to a lung recruitment effect. However, since CT or no other tests were performed to prove the improvement in air content, and EIT only looks at impedance changes, it was not strictly proven that recruitment was the reason for the improvement in ventilation. Moreover, tracheomalacia was not assessed. Therefore, no mechanism of improved ventilation can be stated with certainty. Based on these EIT assessments, we were able to provide the patient with personalized respiratory physiotherapy. We were also able to create an individualized support pad (supine pillow) for lung ventilation. Children with severe neurological impairments often have upper airway obstruction and spinal canal stenosis attributable to scoliosis, thereby making respiratory management difficult.1 By measuring impedance changes by electrodes attached to the chest, EIT functions as a non-invasive monitoring device that captures and visualizes local gas movement in the lungs.2 To date, EIT has been used in the pediatric field to evaluate ventilation when determining the effectiveness of recruitment maneuvers and to evaluate the distribution of ventilation in critically ill children.3 Additionally, EIT can be used for repeated bedside monitoring. It has been used for rehabilitation evaluation4 and has been shown to be useful for adult patients with scoliosis.5 No report in the literature has described the use of EIT for respiratory rehabilitation in children. However, this study revealed that EIT can provide useful information for children with severe neurological impairments and scoliosis. Additionally, EIT facilitated the sharing of ventilation distribution and on-the-spot quantitative evaluation of respiratory physiotherapy at the bedside, which was effective for unifying the entire team's perception of treatment efficacy. When EIT was used for rehabilitation evaluation, it was demonstrated as useful for the entire team to see that ventilation changes with minor positioning such as neck orientation and upper body elevation. Sho Kimura wrote the manuscript. Masahiko Sato and Kentaro Sano helped in drafting the manuscript. Kentaro Sano and Kyohei Shimoyama were responsible for treating the patient. Takafumi Honda, Kumi Yasukawa, and Jun-ichi Takanashi provided critical revision of the manuscript. All authors read and approved the final manuscript. The patient's parent provided written consent for the publication of this case report. We wish to thank the physical therapists, especially Ms. Ayaka Sakamoto, and the medical engineer teams for their attentive medical care. The authors declare no conflict of interest.