A simulation study of diffusion-convection interaction and its effect on multiple breath washout indices

Publication date: Available online 27 September 2018Source: Respiratory Physiology & NeurobiologyAuthor(s): Sylvia Verbanck, Manuel PaivaAbstractExperimental studies of peripheral ventilation heterogeneity via multiple breath washout derived index Sacin have shown its potential to pick up structural change in lung disease. Recent Sacin data suggest that even when intra-acinar structure is unaltered, the combination of convection, diffusion and number of acini fed by patent terminal bronchioles can modify Sacin. We show here how Sacin is affected by structural features such as the secondary alveolar septa, intra-acinar ramification and number of ventilated acini. The simulations also predict relationships between respective alterations in Sacin and washout indices such as lung clearance index (LCI) and alveolar mixing efficiency (AME). This was verified experimentally, with highly significant correlations between Sacin and LCI (r=+0.85;p < 0.001) and between Sacin and AME (r=-0.92;p < 0.001). We have shown how acinar ventilation heterogeneity can be affected by a reduction of number of ventilated acini, a change in overall alveolization or in intra-acinar alveolization pattern, via their impact on the balance between convection and diffusion at acinar level.Graphical abstract

Source: Respiratory Physiology and Neurobiology - October 5, 2018 Category: Respiratory Medicine Source Type: research