Chest physiotherapy improves regional lung volume in ventilated children

Dear Editor, Chest physiotherapy (CPT) is widely used to improve distribution of ventilation and gas exchange in the management of mechanically ventilated infants and children with lung disease [1]. The mechanism by which CPT works is not well understood due to the lack of appropriate outcome measures capable of quantifying changes in ventilation distribution. Electrical impedance tomography (EIT), a non-invasive means of measuring ventilation distribution, is a potential tool to measure CPT effects on lung function in ventilated infants and children [2]. We describe, using EIT, the effect of CPT compared with receiving endotracheal suction only on ventilation distribution and gas exchange in children. A secondary analysis of data previously collected within a prospective randomised controlled trial investigating the effect of recruitment manoeuvres on 60 ventilated children following endotracheal (ETT) suction was conducted in a tertiary paediatric intensive care unit [3]. Children who, based on clinical indication, had received CPT for intensive airway clearance were compared to children receiving suction only. CPT compromised any combination of manual techniques and manual hyperinflation followed by open ETT suctioning [1]. Ventilation distribution (amplitude, global ventilation inhomogeneity, geometric centre) and endexpiratory lung volume (EELV) were measured using EIT (Gottingen GoeMF II, VIASYS Healthcare, Hochberg, Germany) prior to CPT and suction, and then 30, 60 and 120 min post-intervention. Gas exchange (arterial blood gases and oxygen saturation) and physiological variables (heart rate and respiratory rate) were recorded. Linear mixed models were used to determine differences and interactions between those who did and did not receive CPT, over the four time points, for each dependent variable. As this was a secondary analysis of data, we also examined interactions with recruitment manoeuvres and found that the effects of CPT were independent of lung recruitment manoeuvres (p > 0.05). Seventeen participants (28%) received CPT (28.7 ± 49.3months), and forty-three participants (72%) received no CPT (47.8 ± 55.8months) (p = 0.22). Ventilator settings remained constant preand post-intervention. No differences were found at baseline between the two groups for all parameters except PaCO2, which was significantly higher in the CPT group (Table 1), indicative


Dear Editor,
Chest physiotherapy (CPT) is widely used to improve distribution of ventilation and gas exchange in the management of mechanically ventilated infants and children with lung disease [1]. The mechanism by which CPT works is not well understood due to the lack of appropriate outcome measures capable of quantifying changes in ventilation distribution. Electrical impedance tomography (EIT), a non-invasive means of measuring ventilation distribution, is a potential tool to measure CPT effects on lung function in ventilated infants and children [2]. We describe, using EIT, the effect of CPT compared with receiving endotracheal suction only on ventilation distribution and gas exchange in children.
A secondary analysis of data previously collected within a prospective randomised controlled trial investigating the effect of recruitment manoeuvres on 60 ventilated children following endotracheal (ETT) suction was conducted in a tertiary paediatric intensive care unit [3]. Children who, based on clinical indication, had received CPT for intensive airway clearance were compared to children receiving suction only. CPT compromised any combination of manual techniques and manual hyperinflation followed by open ETT suctioning [1].
Ventilation distribution (amplitude, global ventilation inhomogeneity, geometric centre) and endexpiratory lung volume (EELV) were measured using EIT (Gottingen GoeMF II, VIASYS Healthcare, Hochberg, Germany) prior to CPT and suction, and then 30, 60 and 120 min post-intervention. Gas exchange (arterial blood gases and oxygen saturation) and physiological variables (heart rate and respiratory rate) were recorded.
Linear mixed models were used to determine differences and interactions between those who did and did not receive CPT, over the four time points, for each dependent variable. As this was a secondary analysis of data, we also examined interactions with recruitment manoeuvres and found that the effects of CPT were independent of lung recruitment manoeuvres (p > 0.05).
Seventeen participants (28%) received CPT (28.7 ± 49.3 months), and forty-three participants (72%) received no CPT (47.8 ± 55.8 months) (p = 0.22). Ventilator settings remained constant pre-and post-intervention. No differences were found at baseline between the two groups for all parameters except PaCO 2 , which was significantly higher in the CPT group (Table 1), indicative © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. of ventilation maldistribution, more extensive lung disease and was a clinical trigger for CPT. Similar to previous studies, the differences we found in CO 2 between CPT and suction remained consistent after intervention [4,5].
In the CPT group, EELV changes at all measurement points were significantly greater (p < 0.001), indicative of either recruitment of atelectatic alveoli or further distention of already ventilated alveoli [6] ( Table 2). The increase in EELV as a result of lung recruitment secondary to secretion removal is supported by the finding of movement of the geometric centre toward the dependent lung in the children receiving CPT (p = 0.005), indicating improved ventilation posteriorly. CPT mobilises secretions from peripheral airways of the lung where the secretions can cause collapse of distal alveoli, whereas suction removes secretions from the proximal airways and has minimal effect on peripheral secretion clearance. A higher global inhomogeneity index after CPT (p = 0.017) reflected greater variations in ventilation distribution and regionally opening lung fields.
No differences for global amplitude (p = 0.74) between those receiving CPT and those who did not were found, which is not unexpected as all participants were fully volume-controlled ventilated.
Improvements in EELV, geometric centre and global inhomogeneity occurred within 30 min of receiving CPT (p < 0.01) suggesting that by facilitating secretion clearance, CPT can result in immediate changes in Stepwise recruitment 6 (35%) 14 (33%)
We have shown that EIT can detect regional changes in lung function as a result of CPT in ventilated infants and children, making it a potential clinical tool to measure the effects of CPT and for focusing CPT to areas of concern.