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Effect of PEEP and tidal volume on ventilation distribution and end-expiratory lung volume: a prospective experimental animal and pilot clinical study.

Zick G, Elke G, Becher T, Schädler D, Pulletz S, Freitag-Wolf S, Weiler N, Frerichs I - PLoS ONE (2013)

Bottom Line: In healthy animals, high compared to low VT increased C(RS) and ventilation in dependent lung regions implying tidal recruitment.ALI reduced C(RS) and EELV in all regions without changing ventilation distribution.Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional C(RS).

View Article: PubMed Central - PubMed

Affiliation: University Medical Center Schleswig-Holstein, Campus Kiel, Department of Anesthesiology and Intensive Care Medicine, Kiel, Germany. guenther.zick@uksh.de

ABSTRACT

Introduction: Lung-protective ventilation aims at using low tidal volumes (VT) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of VT and PEEP on ventilation distribution, regional respiratory system compliance (C(RS)), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation.

Methods: EIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight VT and 5 cmH2O PEEP. After ALI induction, 10 ml/kg VT and 10 cmH2O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high VT ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional C(RS) and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high VT ventilation (6 and 10 (8) ml/kg) at three PEEP levels.

Results: In healthy animals, high compared to low VT increased C(RS) and ventilation in dependent lung regions implying tidal recruitment. ALI reduced C(RS) and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH2O (mean±SD) resulted in comparable increase in C(RS) in dependent and decrease in non-dependent regions at both VT. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of VT. In patients, regional C(RS) differences between low and high VT revealed high degree of tidal recruitment and low overinflation at 3±1 cmH2O PEEP. Tidal recruitment decreased at 10±1 cmH2O and was further reduced at 15±2 cmH(2)O PEEP.

Conclusions: Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional C(RS).

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Center of ventilation.Ventilation distribution during individual measurement time points represented by the geometrical center of ventilation. The center of ventilation is given in percent of the anteroposterior chest diameter. Values above 50 indicate a location in the dorsal half of the chest cross-section. The median, the 25th and the 75th percentile, minimum and maximum values of ten animals are shown. The gray areas in the diagram show the positive end-expiratory pressure (PEEP) values during the individual measurement time points. Significant differences between corresponding high VT and low VT are indicated. Every group with ALI and high PEEP is significantly different from normal lung and ALI with PEEP 10 cm H2O (Time point 2). Left Y axis: center of ventilation, right Y axis: PEEP. High VT, ventilation with 10 ml/kg BW, low VT, ventilation with 5 ml/kg BW.
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pone-0072675-g004: Center of ventilation.Ventilation distribution during individual measurement time points represented by the geometrical center of ventilation. The center of ventilation is given in percent of the anteroposterior chest diameter. Values above 50 indicate a location in the dorsal half of the chest cross-section. The median, the 25th and the 75th percentile, minimum and maximum values of ten animals are shown. The gray areas in the diagram show the positive end-expiratory pressure (PEEP) values during the individual measurement time points. Significant differences between corresponding high VT and low VT are indicated. Every group with ALI and high PEEP is significantly different from normal lung and ALI with PEEP 10 cm H2O (Time point 2). Left Y axis: center of ventilation, right Y axis: PEEP. High VT, ventilation with 10 ml/kg BW, low VT, ventilation with 5 ml/kg BW.

Mentions: Increasing VT in the healthy lung from 5 to 10 ml/kg BW led to a small but significant redistribution of ventilation in favor of the dependent lung regions. The geometrical center of ventilation moved slightly but significantly downwards (Figure 4). This went along with an increase in regional CRS in the dependent parts of the lung (Figure 3).


Effect of PEEP and tidal volume on ventilation distribution and end-expiratory lung volume: a prospective experimental animal and pilot clinical study.

Zick G, Elke G, Becher T, Schädler D, Pulletz S, Freitag-Wolf S, Weiler N, Frerichs I - PLoS ONE (2013)

Center of ventilation.Ventilation distribution during individual measurement time points represented by the geometrical center of ventilation. The center of ventilation is given in percent of the anteroposterior chest diameter. Values above 50 indicate a location in the dorsal half of the chest cross-section. The median, the 25th and the 75th percentile, minimum and maximum values of ten animals are shown. The gray areas in the diagram show the positive end-expiratory pressure (PEEP) values during the individual measurement time points. Significant differences between corresponding high VT and low VT are indicated. Every group with ALI and high PEEP is significantly different from normal lung and ALI with PEEP 10 cm H2O (Time point 2). Left Y axis: center of ventilation, right Y axis: PEEP. High VT, ventilation with 10 ml/kg BW, low VT, ventilation with 5 ml/kg BW.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3750001&req=5

pone-0072675-g004: Center of ventilation.Ventilation distribution during individual measurement time points represented by the geometrical center of ventilation. The center of ventilation is given in percent of the anteroposterior chest diameter. Values above 50 indicate a location in the dorsal half of the chest cross-section. The median, the 25th and the 75th percentile, minimum and maximum values of ten animals are shown. The gray areas in the diagram show the positive end-expiratory pressure (PEEP) values during the individual measurement time points. Significant differences between corresponding high VT and low VT are indicated. Every group with ALI and high PEEP is significantly different from normal lung and ALI with PEEP 10 cm H2O (Time point 2). Left Y axis: center of ventilation, right Y axis: PEEP. High VT, ventilation with 10 ml/kg BW, low VT, ventilation with 5 ml/kg BW.
Mentions: Increasing VT in the healthy lung from 5 to 10 ml/kg BW led to a small but significant redistribution of ventilation in favor of the dependent lung regions. The geometrical center of ventilation moved slightly but significantly downwards (Figure 4). This went along with an increase in regional CRS in the dependent parts of the lung (Figure 3).

Bottom Line: In healthy animals, high compared to low VT increased C(RS) and ventilation in dependent lung regions implying tidal recruitment.ALI reduced C(RS) and EELV in all regions without changing ventilation distribution.Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional C(RS).

View Article: PubMed Central - PubMed

Affiliation: University Medical Center Schleswig-Holstein, Campus Kiel, Department of Anesthesiology and Intensive Care Medicine, Kiel, Germany. guenther.zick@uksh.de

ABSTRACT

Introduction: Lung-protective ventilation aims at using low tidal volumes (VT) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of VT and PEEP on ventilation distribution, regional respiratory system compliance (C(RS)), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation.

Methods: EIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight VT and 5 cmH2O PEEP. After ALI induction, 10 ml/kg VT and 10 cmH2O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high VT ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional C(RS) and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high VT ventilation (6 and 10 (8) ml/kg) at three PEEP levels.

Results: In healthy animals, high compared to low VT increased C(RS) and ventilation in dependent lung regions implying tidal recruitment. ALI reduced C(RS) and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH2O (mean±SD) resulted in comparable increase in C(RS) in dependent and decrease in non-dependent regions at both VT. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of VT. In patients, regional C(RS) differences between low and high VT revealed high degree of tidal recruitment and low overinflation at 3±1 cmH2O PEEP. Tidal recruitment decreased at 10±1 cmH2O and was further reduced at 15±2 cmH(2)O PEEP.

Conclusions: Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional C(RS).

Show MeSH
Related in: MedlinePlus