Limits...
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
The shape of intra-tidal dynamic compliance calculated with the SLICE method in the same patient as in Figures 1 and 2. An upward slope indicates recruitment, a downward slope indicates overdistension and a quasi-horizontal shape indicates that neither the recruitment nor the overdistension effect is dominant. Positive end-expiratory pressure (PEEP) is optimized at 14 mbar in this patient according to the shape of the compliance (C)-volume curve.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2875520&req=5

Figure 4: The shape of intra-tidal dynamic compliance calculated with the SLICE method in the same patient as in Figures 1 and 2. An upward slope indicates recruitment, a downward slope indicates overdistension and a quasi-horizontal shape indicates that neither the recruitment nor the overdistension effect is dominant. Positive end-expiratory pressure (PEEP) is optimized at 14 mbar in this patient according to the shape of the compliance (C)-volume curve.

Mentions: According to the intra-tidal compliance-volume curves calculated with the SLICE method, another optimal PEEP level with respect to lung mechanics was obtained for every patient. Figure 4 shows typical intra-tidal compliance-volume curves in the same patient as in Figures 2 and 3. Positive slope (upwards direction) of the compliance-volume curves at a low PEEP indicates ongoing recruitment in inflation, while a negative slope (downwards direction) indicates overdistension of alveoli. PEEP is optimized when quasi-constant compliance within tidal breath is obtained [12].


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)

The shape of intra-tidal dynamic compliance calculated with the SLICE method in the same patient as in Figures 1 and 2. An upward slope indicates recruitment, a downward slope indicates overdistension and a quasi-horizontal shape indicates that neither the recruitment nor the overdistension effect is dominant. Positive end-expiratory pressure (PEEP) is optimized at 14 mbar in this patient according to the shape of the compliance (C)-volume curve.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: The shape of intra-tidal dynamic compliance calculated with the SLICE method in the same patient as in Figures 1 and 2. An upward slope indicates recruitment, a downward slope indicates overdistension and a quasi-horizontal shape indicates that neither the recruitment nor the overdistension effect is dominant. Positive end-expiratory pressure (PEEP) is optimized at 14 mbar in this patient according to the shape of the compliance (C)-volume curve.
Mentions: According to the intra-tidal compliance-volume curves calculated with the SLICE method, another optimal PEEP level with respect to lung mechanics was obtained for every patient. Figure 4 shows typical intra-tidal compliance-volume curves in the same patient as in Figures 2 and 3. Positive slope (upwards direction) of the compliance-volume curves at a low PEEP indicates ongoing recruitment in inflation, while a negative slope (downwards direction) indicates overdistension of alveoli. PEEP is optimized when quasi-constant compliance within tidal breath is obtained [12].

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