Visualizing pursed lips breathing of patients with chronic obstructive pulmonary disease through evaluation of global and regional ventilation using electrical impedance tomography

Abstract

Objective:
This study aims to explore the possibility of using electrical impedance tomography (EIT) to assess PLB performance of patients with COPD.
Methods:
32 patients with COPD were assigned equally to either the conventional group or the EIT guided group. All patients were taught to perform PLB by a physiotherapist without EIT in the conventional group or with EIT in the EIT guided group for 10 min. The ventilation of all patients in the final test were continuously monitored using EIT and the PLB performances were rated by another physiotherapist before and after reviewing EIT. The global and regional ventilation between two groups as well as between quite breathing (QB) and PLB were compared and rating scores with and without EIT were also compared.
Results:
For global ventilation, the inspiratory depth and the ratio of expiratory-to-inspiratory time during PLB was significantly larger than those during QB for both group (P<0.001). The inspiratory depth and the ratio of expiratory-to-inspiratory time during PLB in the EIT guided group were higher compared to those in the conventional group (P<0.001), as well as expiratory flow expiratory uniformity and respiratory stability were better (P<0.001). For regional ventilation, center of ventilation significantly decreased during PLB (P<0.05). The expiratory time constant during PLB in the EIT guided group was greater than that in the conventional group (P<0.001). Additionally, Bland-Altman plots analysis suggested a high concordance between subjective rating and rating with the help of EIT, but the score rated after EIT observation significantly lower than that rated subjectively in both groups (score drop of -2.68±1.1 in the conventional group and -1.19±0.72 in the EIT guided group, P<0.01).
Conclusion:
EIT could capture the details of PLB maneuver, which might be a potential tool to quantitatively evaluate PLB performance and thus assist physiotherapists to teach PLB maneuver to patients.