Mapping regional strain in anesthetised healthy subjects during spontaneous ventilation
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Fecha
2019
Autores
Cruces, Pablo
Erranz, Benjamin
Lillo, Felipe
Sarabia-Vallejos, Mauricio A.
Iturrieta, Pablo
Morales, Felipe
Blaha, Katherine
Medina, Tania
Diaz, Franco
Hurtado, Daniel E.
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
BMJ Open Respiratory Research
Nombre de Curso
Licencia CC
Attribution-Non Commercial 4.0 International (CC BY-NC 4.0)
Licencia CC
https://creativecommons.org/licenses/by-nc/4.0/
Resumen
Introduction Breathing produces a phenomenon of cyclic deformation throughout life. Biomechanically, deformation of the lung is measured as strain. Regional strain recently started to be recognised as a tool in the study of lung pathophysiology, but regional lung strain has not been studied in healthy subjects breathing spontaneously without voluntary or pharmacological control of ventilation. Our aim is to generate three-dimensional (3D) regional strain and heterogeneity maps of healthy rat lungs and describe their changes over time. Methods Micro-CT and image-based biomechanical analysis by finite element approach were carried out in six anaesthetised rats under spontaneous breathing in two different states, at the beginning of the experiment and after 3 hours of observation. 3D regional strain maps were constructed and divided into 10 isovolumetric region-of-interest (ROI) in three directions (apex to base, dorsal to ventral and costal to mediastinal), allowing to regionally analyse the volumetric strain, the strain progression and the strain heterogeneity. To describe in depth these parameters, and systematise their report, we defined regional strain heterogeneity index [1+strain SD ROI(x)]/[1+strain mean ROI(x)] and regional strain progression index [ROI(x)-mean of final strain/ROI(x)-mean of initial strain]. Results We were able to generate 3D regional strain maps of the lung in subjects without respiratory support, showing significant differences among the three analysed axes. We observed a significantly lower regional volumetric strain in the apex sector compared with the base, with no significant anatomical systematic differences in the other directions. This heterogeneity could not be identified with physiological or standard CT methods. There was no progression of the analysed regional volumetric strain when the two time-points were compared. Discussion It is possible to map the regional volumetric strain in the lung for healthy subjects during spontaneous breathing. Regional strain heterogeneity and changes over time can be measured using a CT image-based numerical analysis applying a finite element approach. These results support that healthy lung might have significant regional strain and its spatial distribution is highly heterogeneous. This protocol for CT image acquisition and analysis could be a useful tool for helping to understand the mechanobiology of the lung in many diseases.
Notas
Indexación Scopus
Palabras clave
image-based biomechanical analysis, lung heterogeneity, lung physiology, lung strain, spontaneous breathing
Citación
BMJ Open Respiratory Research Volume 6, Issue 1 2019 Article number e000423
DOI
10.1136/bmjresp-2019-000423