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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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Related in: MedlinePlus

Study flowchart.Ten animals were studied during volume-controlled ventilation during ventilation with 5 ml/kg (baseline) and 10 ml/kg tidal volume (VT) (measurement time point 1) in the normal lung (NL) as well as after induction of acute lung injury (ALI) (time point 2) at inspired fractions of oxygen of 0.5 and 1.0, respectively. Then a constant low-flow inflation maneuver (pressure-volume (PV) maneuver) was performed and positive end-expiratory pressure (PEEP) was set 2 cm H2O above the lower inflection point (LIP) identified in the PV curve. Using a crossover design, further measurements were performed 5 and 30 min after ventilation with low VT and active interventional lung assist (ILA) and after another 5 and 30 min with high VT and inactive ILA (no ILA) (time points 3–6). Five animals were randomly ventilated in the reversed chronological order. Ventilator settings of VT and PEEP at each measurement time point are shown in the lower part of the Figure. *, time elapsed after the change in ventilator and ILA settings.
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pone-0072675-g001: Study flowchart.Ten animals were studied during volume-controlled ventilation during ventilation with 5 ml/kg (baseline) and 10 ml/kg tidal volume (VT) (measurement time point 1) in the normal lung (NL) as well as after induction of acute lung injury (ALI) (time point 2) at inspired fractions of oxygen of 0.5 and 1.0, respectively. Then a constant low-flow inflation maneuver (pressure-volume (PV) maneuver) was performed and positive end-expiratory pressure (PEEP) was set 2 cm H2O above the lower inflection point (LIP) identified in the PV curve. Using a crossover design, further measurements were performed 5 and 30 min after ventilation with low VT and active interventional lung assist (ILA) and after another 5 and 30 min with high VT and inactive ILA (no ILA) (time points 3–6). Five animals were randomly ventilated in the reversed chronological order. Ventilator settings of VT and PEEP at each measurement time point are shown in the lower part of the Figure. *, time elapsed after the change in ventilator and ILA settings.

Mentions: A flowchart of the experimental protocol is provided in Figure 1. EIT scanning was performed during baseline conditions and at six subsequent measurement time points as described below:


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)

Study flowchart.Ten animals were studied during volume-controlled ventilation during ventilation with 5 ml/kg (baseline) and 10 ml/kg tidal volume (VT) (measurement time point 1) in the normal lung (NL) as well as after induction of acute lung injury (ALI) (time point 2) at inspired fractions of oxygen of 0.5 and 1.0, respectively. Then a constant low-flow inflation maneuver (pressure-volume (PV) maneuver) was performed and positive end-expiratory pressure (PEEP) was set 2 cm H2O above the lower inflection point (LIP) identified in the PV curve. Using a crossover design, further measurements were performed 5 and 30 min after ventilation with low VT and active interventional lung assist (ILA) and after another 5 and 30 min with high VT and inactive ILA (no ILA) (time points 3–6). Five animals were randomly ventilated in the reversed chronological order. Ventilator settings of VT and PEEP at each measurement time point are shown in the lower part of the Figure. *, time elapsed after the change in ventilator and ILA settings.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0072675-g001: Study flowchart.Ten animals were studied during volume-controlled ventilation during ventilation with 5 ml/kg (baseline) and 10 ml/kg tidal volume (VT) (measurement time point 1) in the normal lung (NL) as well as after induction of acute lung injury (ALI) (time point 2) at inspired fractions of oxygen of 0.5 and 1.0, respectively. Then a constant low-flow inflation maneuver (pressure-volume (PV) maneuver) was performed and positive end-expiratory pressure (PEEP) was set 2 cm H2O above the lower inflection point (LIP) identified in the PV curve. Using a crossover design, further measurements were performed 5 and 30 min after ventilation with low VT and active interventional lung assist (ILA) and after another 5 and 30 min with high VT and inactive ILA (no ILA) (time points 3–6). Five animals were randomly ventilated in the reversed chronological order. Ventilator settings of VT and PEEP at each measurement time point are shown in the lower part of the Figure. *, time elapsed after the change in ventilator and ILA settings.
Mentions: A flowchart of the experimental protocol is provided in Figure 1. EIT scanning was performed during baseline conditions and at six subsequent measurement time points as described below:

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