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PEEP titration guided by ventilation homogeneity: a feasibility study using electrical impedance tomography.

Zhao Z, Steinmann D, Frerichs I, Guttmann J, Möller K - Crit Care (2010)

Bottom Line: Ventilation distribution was monitored by EIT.No significant differences in the results were observed between the GI index method (12.2 +/- 4.6 mbar) and the dynamic compliance method (11.4 +/- 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume curve method (12.2 +/- 4.9 mbar, P > 0.6).The GI index may provide new insights into the relationship between lung mechanics and tidal volume distribution and may be used to guide ventilator settings.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Furtwangen University, Jakob-Kienzle-Strasse 17, D-78054 Villingen-Schwenningen, Germany. zhanqi.zhao@hs-furtwangen.de

ABSTRACT

Introduction: Lung protective ventilation requires low tidal volume and suitable positive end-expiratory pressure (PEEP). To date, few methods have been accepted for clinical use to set the appropriate PEEP. The aim of this study was to test the feasibility of PEEP titration guided by ventilation homogeneity using the global inhomogeneity (GI) index based on electrical impedance tomography (EIT) images.

Methods: In a retrospective study, 10 anesthetized patients with healthy lungs mechanically ventilated under volume-controlled mode were investigated. Ventilation distribution was monitored by EIT. A standardized incremental PEEP trial (PEEP from 0 to 28 mbar, 2 mbar per step) was conducted. During the PEEP trial, "optimal" PEEP level for each patient was determined when the air was most homogeneously distributed in the lung, indicated by the lowest GI index value. Two published methods for setting PEEP were included for comparison based on the maximum global dynamic compliance and the intra-tidal compliance-volume curve.

Results: No significant differences in the results were observed between the GI index method (12.2 +/- 4.6 mbar) and the dynamic compliance method (11.4 +/- 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume curve method (12.2 +/- 4.9 mbar, P > 0.6).

Conclusions: According to the results, it is feasible and reasonable to use the GI index to select the PEEP level with respect to ventilation homogeneity. The GI index may provide new insights into the relationship between lung mechanics and tidal volume distribution and may be used to guide ventilator settings.

Show MeSH
Comparison of the optimal PEEP determined with the GI index, dynamic compliance and compliance-volume curve method. Left = box plot. The boxes mark the quartiles while the whiskers extend from the box out to the most extreme data value within 1.5 times the interquartile range of the sample. Middle = Bland-Altman plot comparing global inhomogeneity (GI) and dynamic compliance method (Cdyn). Right = Bland-Altman plot comparing GI and the intra-tidal compliance-volume curve calculated by the SLICE method (C_V). The numbers above the * indicate the number of overlapping results. The dashed line at the middle depicts the mean value of the whole data set. The other two dashed lines represent mean ± 1.96 times standard deviation.
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Figure 5: Comparison of the optimal PEEP determined with the GI index, dynamic compliance and compliance-volume curve method. Left = box plot. The boxes mark the quartiles while the whiskers extend from the box out to the most extreme data value within 1.5 times the interquartile range of the sample. Middle = Bland-Altman plot comparing global inhomogeneity (GI) and dynamic compliance method (Cdyn). Right = Bland-Altman plot comparing GI and the intra-tidal compliance-volume curve calculated by the SLICE method (C_V). The numbers above the * indicate the number of overlapping results. The dashed line at the middle depicts the mean value of the whole data set. The other two dashed lines represent mean ± 1.96 times standard deviation.

Mentions: Figure 5 shows the comparison of these methods in a box plot and Bland-Altman plots (GI index vs. dynamic compliance; GI index vs. compliance-volume curve). No significant differences in the results were found between the GI index method (12.2 ± 4.6 mbar) and the dynamic compliance method (11.4 ± 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume method (12.2 ± 4.9 mbar, P > 0.6). Considering the quasi-plateau phases in compliance-pressure curves, the large differences between the results obtained with the GI index and the dynamic compliance method in some patients were explainable. No bias of results was observed in the Bland-Altman analysis.


PEEP titration guided by ventilation homogeneity: a feasibility study using electrical impedance tomography.

Zhao Z, Steinmann D, Frerichs I, Guttmann J, Möller K - Crit Care (2010)

Comparison of the optimal PEEP determined with the GI index, dynamic compliance and compliance-volume curve method. Left = box plot. The boxes mark the quartiles while the whiskers extend from the box out to the most extreme data value within 1.5 times the interquartile range of the sample. Middle = Bland-Altman plot comparing global inhomogeneity (GI) and dynamic compliance method (Cdyn). Right = Bland-Altman plot comparing GI and the intra-tidal compliance-volume curve calculated by the SLICE method (C_V). The numbers above the * indicate the number of overlapping results. The dashed line at the middle depicts the mean value of the whole data set. The other two dashed lines represent mean ± 1.96 times standard deviation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2875520&req=5

Figure 5: Comparison of the optimal PEEP determined with the GI index, dynamic compliance and compliance-volume curve method. Left = box plot. The boxes mark the quartiles while the whiskers extend from the box out to the most extreme data value within 1.5 times the interquartile range of the sample. Middle = Bland-Altman plot comparing global inhomogeneity (GI) and dynamic compliance method (Cdyn). Right = Bland-Altman plot comparing GI and the intra-tidal compliance-volume curve calculated by the SLICE method (C_V). The numbers above the * indicate the number of overlapping results. The dashed line at the middle depicts the mean value of the whole data set. The other two dashed lines represent mean ± 1.96 times standard deviation.
Mentions: Figure 5 shows the comparison of these methods in a box plot and Bland-Altman plots (GI index vs. dynamic compliance; GI index vs. compliance-volume curve). No significant differences in the results were found between the GI index method (12.2 ± 4.6 mbar) and the dynamic compliance method (11.4 ± 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume method (12.2 ± 4.9 mbar, P > 0.6). Considering the quasi-plateau phases in compliance-pressure curves, the large differences between the results obtained with the GI index and the dynamic compliance method in some patients were explainable. No bias of results was observed in the Bland-Altman analysis.

Bottom Line: Ventilation distribution was monitored by EIT.No significant differences in the results were observed between the GI index method (12.2 +/- 4.6 mbar) and the dynamic compliance method (11.4 +/- 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume curve method (12.2 +/- 4.9 mbar, P > 0.6).The GI index may provide new insights into the relationship between lung mechanics and tidal volume distribution and may be used to guide ventilator settings.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Furtwangen University, Jakob-Kienzle-Strasse 17, D-78054 Villingen-Schwenningen, Germany. zhanqi.zhao@hs-furtwangen.de

ABSTRACT

Introduction: Lung protective ventilation requires low tidal volume and suitable positive end-expiratory pressure (PEEP). To date, few methods have been accepted for clinical use to set the appropriate PEEP. The aim of this study was to test the feasibility of PEEP titration guided by ventilation homogeneity using the global inhomogeneity (GI) index based on electrical impedance tomography (EIT) images.

Methods: In a retrospective study, 10 anesthetized patients with healthy lungs mechanically ventilated under volume-controlled mode were investigated. Ventilation distribution was monitored by EIT. A standardized incremental PEEP trial (PEEP from 0 to 28 mbar, 2 mbar per step) was conducted. During the PEEP trial, "optimal" PEEP level for each patient was determined when the air was most homogeneously distributed in the lung, indicated by the lowest GI index value. Two published methods for setting PEEP were included for comparison based on the maximum global dynamic compliance and the intra-tidal compliance-volume curve.

Results: No significant differences in the results were observed between the GI index method (12.2 +/- 4.6 mbar) and the dynamic compliance method (11.4 +/- 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume curve method (12.2 +/- 4.9 mbar, P > 0.6).

Conclusions: According to the results, it is feasible and reasonable to use the GI index to select the PEEP level with respect to ventilation homogeneity. The GI index may provide new insights into the relationship between lung mechanics and tidal volume distribution and may be used to guide ventilator settings.

Show MeSH