Victor M, Melo J, Roldán R, Nakamura M, Tucci M, Costa E, Amato M, Yoneyama T, Tanaka H. Modelling approach to obtain regional respiratory mechanics using electrical impedance tomography and volume-dependent elastance model.
Physiol Meas 2019;
40:045001. [PMID:
30921784 DOI:
10.1088/1361-6579/ab144a]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE
This paper presents a method for breath-by-breath estimation of regional respiratory mechanics without the need for special manoeuvres (such as inspiratory pause or low-flow inflation) using electrical impedance tomography (EIT) associated with pressure/airflow waveforms.
APPROACH
We developed a method to estimate regional parameters using the regional impedance fraction, by multiplying it by global flow and volume waveforms. A volume-dependent elastance model was used to obtain compliance, resistance, volume-independent (E 1), and volume-dependent (E 2) components. Three swine under invasive mechanical ventilation were used to assess internal consistency and illustrate potential applications of our method. One animal (case 1) was ventilated with a broad range of tidal volumes to compare the consistency between regional and global resistances and compliances. Two other animals (cases 2 and 3) had respiratory compliance decreased, respectively, by overdistension and collapse as quantified by x-ray computed tomography.
MAIN RESULTS
In case 1, derived global estimates obtained from the independent regional estimates were strongly associated with direct measurements of global mechanics (correlation coefficients of 0.9976 and 0.9981 for compliances and resistances, respectively), suggesting consistency of our modelling. In cases 2 and 3, the development of lung overdistension and collapse over time was captured by regional estimates.
CONCLUSIONS
Using EIT and pressure/airflow waveforms, regional respiratory parameters can be obtained cycle-by-cycle, refining lung function monitoring.
SIGNIFICANCE
The method allows real-time monitoring of regional parameters and their trends over time, which might be helpful to differentiate deterioration in lung compliance due to overdistension or collapse.
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