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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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Regional differences in respiratory system compliance.Differences in regional respiratory system compliance (ΔCRS) in 32 regions of interest in the chest cross-section in five patients with ARDS between ventilation at high and low tidal volume (VT) at three levels of positive end-expiratory pressure set according to the lower inflection point (LIP) of the quasistatic pressure-volume curve. ΔCRS are presented as ventrodorsal profiles. Values are means ±SD.
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pone-0072675-g006: Regional differences in respiratory system compliance.Differences in regional respiratory system compliance (ΔCRS) in 32 regions of interest in the chest cross-section in five patients with ARDS between ventilation at high and low tidal volume (VT) at three levels of positive end-expiratory pressure set according to the lower inflection point (LIP) of the quasistatic pressure-volume curve. ΔCRS are presented as ventrodorsal profiles. Values are means ±SD.

Mentions: Respiratory and hemodynamic data are given in Table 3. LIP was identified at 8±2 cm H2O. Regional CRS differences at the respective PEEP levels are shown in Figure 6. At the lowest PEEP of 3±1 cm H2O we found a pronounced increase in CRS in the dorsal regions and a small decrease in the ventral regions with high VT. At PEEP of 10±1 cm H2O, high VT led to a smaller increase in CRS in the dorsal regions and more pronounced reduction in the ventral parts than at the lowest PEEP. At PEEP of 15±2 cm H2O, the CRS difference between high and low VT was even smaller.


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)

Regional differences in respiratory system compliance.Differences in regional respiratory system compliance (ΔCRS) in 32 regions of interest in the chest cross-section in five patients with ARDS between ventilation at high and low tidal volume (VT) at three levels of positive end-expiratory pressure set according to the lower inflection point (LIP) of the quasistatic pressure-volume curve. ΔCRS are presented as ventrodorsal profiles. Values are means ±SD.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0072675-g006: Regional differences in respiratory system compliance.Differences in regional respiratory system compliance (ΔCRS) in 32 regions of interest in the chest cross-section in five patients with ARDS between ventilation at high and low tidal volume (VT) at three levels of positive end-expiratory pressure set according to the lower inflection point (LIP) of the quasistatic pressure-volume curve. ΔCRS are presented as ventrodorsal profiles. Values are means ±SD.
Mentions: Respiratory and hemodynamic data are given in Table 3. LIP was identified at 8±2 cm H2O. Regional CRS differences at the respective PEEP levels are shown in Figure 6. At the lowest PEEP of 3±1 cm H2O we found a pronounced increase in CRS in the dorsal regions and a small decrease in the ventral regions with high VT. At PEEP of 10±1 cm H2O, high VT led to a smaller increase in CRS in the dorsal regions and more pronounced reduction in the ventral parts than at the lowest PEEP. At PEEP of 15±2 cm H2O, the CRS difference between high and low VT was even smaller.

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