Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study
Abstract Background The multiple-breath washout (MBW) is able to provide information about the distribution of ventilation-to-volume (v/V) ratios in the lungs. However, the classical, all-parallel model may return skewed results due to the mixing effect of a common dead space. The aim of this work i...
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| Format: | Article |
| Language: | English |
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BMC
2018-01-01
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| Series: | BioMedical Engineering OnLine |
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| Online Access: | http://link.springer.com/article/10.1186/s12938-018-0442-3 |
| _version_ | 1818407353335152640 |
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| author | Gabriel Casulari Motta-Ribeiro Frederico Caetano Jandre Hermann Wrigge Antonio Giannella-Neto |
| author_facet | Gabriel Casulari Motta-Ribeiro Frederico Caetano Jandre Hermann Wrigge Antonio Giannella-Neto |
| author_sort | Gabriel Casulari Motta-Ribeiro |
| collection | DOAJ |
| description | Abstract Background The multiple-breath washout (MBW) is able to provide information about the distribution of ventilation-to-volume (v/V) ratios in the lungs. However, the classical, all-parallel model may return skewed results due to the mixing effect of a common dead space. The aim of this work is to examine whether a novel mathematical model and algorithm is able to estimate v/V of a physical model, and to compare its results with those of the classical model. The novel model takes into account a dead space in series with the parallel ventilated compartments, allows for variable tidal volume (VT) and end-expiratory lung volume (EELV), and does not require a ideal step change of the inert gas concentration. Methods Two physical models with preset v/V units and a common series dead space (vd) were built and mechanically ventilated. The models underwent MBW with N2 as inert gas, throughout which flow and N2 concentration signals were acquired. Distribution of v/V was estimated—via nonnegative least squares, with Tikhonov regularization—with the classical, all-parallel model (with and without correction for non-ideal inspiratory N2 step) and with the new, generalized model including breath-by-breath vd estimates given by the Fowler method (with and without constrained VT and EELV). Results The v/V distributions estimated with constrained EELV and VT by the generalized model were practically coincident with the actual v/V distribution for both physical models. The v/V distributions calculated with the classical model were shifted leftwards and broader as compared to the reference. Conclusions The proposed model and algorithm provided better estimates of v/V than the classical model, particularly with constrained VT and EELV. |
| first_indexed | 2024-12-14T09:26:29Z |
| format | Article |
| id | doaj.art-7dde583df14e453fa1ab464068a7b1d6 |
| institution | Directory Open Access Journal |
| issn | 1475-925X |
| language | English |
| last_indexed | 2024-12-14T09:26:29Z |
| publishDate | 2018-01-01 |
| publisher | BMC |
| record_format | Article |
| series | BioMedical Engineering OnLine |
| spelling | doaj.art-7dde583df14e453fa1ab464068a7b1d62022-12-21T23:08:10ZengBMCBioMedical Engineering OnLine1475-925X2018-01-0117111210.1186/s12938-018-0442-3Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation studyGabriel Casulari Motta-Ribeiro0Frederico Caetano Jandre1Hermann Wrigge2Antonio Giannella-Neto3Pulmonary Engineering Laboratory, Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de JaneiroPulmonary Engineering Laboratory, Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de JaneiroDepartment of Anesthesiology and Intensive Care Medicine, University of LeipzigPulmonary Engineering Laboratory, Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de JaneiroAbstract Background The multiple-breath washout (MBW) is able to provide information about the distribution of ventilation-to-volume (v/V) ratios in the lungs. However, the classical, all-parallel model may return skewed results due to the mixing effect of a common dead space. The aim of this work is to examine whether a novel mathematical model and algorithm is able to estimate v/V of a physical model, and to compare its results with those of the classical model. The novel model takes into account a dead space in series with the parallel ventilated compartments, allows for variable tidal volume (VT) and end-expiratory lung volume (EELV), and does not require a ideal step change of the inert gas concentration. Methods Two physical models with preset v/V units and a common series dead space (vd) were built and mechanically ventilated. The models underwent MBW with N2 as inert gas, throughout which flow and N2 concentration signals were acquired. Distribution of v/V was estimated—via nonnegative least squares, with Tikhonov regularization—with the classical, all-parallel model (with and without correction for non-ideal inspiratory N2 step) and with the new, generalized model including breath-by-breath vd estimates given by the Fowler method (with and without constrained VT and EELV). Results The v/V distributions estimated with constrained EELV and VT by the generalized model were practically coincident with the actual v/V distribution for both physical models. The v/V distributions calculated with the classical model were shifted leftwards and broader as compared to the reference. Conclusions The proposed model and algorithm provided better estimates of v/V than the classical model, particularly with constrained VT and EELV.http://link.springer.com/article/10.1186/s12938-018-0442-3Pulmonary function testsVentilatory distributionsMultiple-breath washoutEnd-expiratory lung volumeFunctional residual capacityDead space |
| spellingShingle | Gabriel Casulari Motta-Ribeiro Frederico Caetano Jandre Hermann Wrigge Antonio Giannella-Neto Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study BioMedical Engineering OnLine Pulmonary function tests Ventilatory distributions Multiple-breath washout End-expiratory lung volume Functional residual capacity Dead space |
| title | Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study |
| title_full | Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study |
| title_fullStr | Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study |
| title_full_unstemmed | Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study |
| title_short | Generalized estimation of the ventilatory distribution from the multiple-breath washout: a bench evaluation study |
| title_sort | generalized estimation of the ventilatory distribution from the multiple breath washout a bench evaluation study |
| topic | Pulmonary function tests Ventilatory distributions Multiple-breath washout End-expiratory lung volume Functional residual capacity Dead space |
| url | http://link.springer.com/article/10.1186/s12938-018-0442-3 |
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