Mechanisms of Regional Lung Expansion in Acute Respiratory Distress Syndrome

1999 ◽  
pp. 252-268
Author(s):  
M. Martynowicz ◽  
R. D. Hubmayr
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Lung Expansion ◽  
Regional Lung

Regional lung viscoelastic properties in supine and prone position in a porcine model of acute respiratory distress syndrome

2021 ◽  
Author(s):  
Claude Guerin ◽  
Sam Bayat ◽  
Norbert Noury ◽  
Martin Cour ◽  
Laurent Argaud ◽  
...  
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Chest Wall ◽  
Prone Position ◽  
Viscoelastic Properties ◽  
Airway Pressure ◽  
Distress Syndrome ◽  
Impedance Tomography ◽  
Regional Lung

Regional viscoelastic properties of thoracic tissues in acute respiratory distress syndrome (ARDS) and their change with position and positive end-expiratory pressure (PEEP) are unknown. In an experimental porcine ARDS, dorsal and ventral lung (R2,L and E2,L) and chest wall (R2,cw and E2,cw) viscoelastic resistive(R) and elastic(E) parameters were measured at 20, 15, 10 and 5 cmH2O PEEP in supine and prone position. E2 and R2 were obtained by fitting the decay of pressure after end-inspiratory occlusion to the equation: Pviscmax(t)=R2 e(-t/τ2), where t is length of occlusion and τ2 time constant. E2 was = R2/τ2. R2,cw and E2,cw were measured from esophageal, dorsal and ventral pleural pressures. Global R2,L and E2,L were obtained from the global trans-pulmonary pressure (airway pressure-esophageal pressure), and regional R2,L and E2,L from the dorsal and ventral airway pressure-pleural pressure difference. Lung ventilation was measured by electrical impedance tomography (EIT). Global R2,cw and E2,cw did not change with PEEP or position. Global R2,L (median(Q1-Q3)) was 37.1(11.0-65.1), 5.1(4.3-5.5), 12.1(8.4-19.5), and 41.0 (26.6-53.5) cmH2O/L/s in supine, and 15.3 (9.1-41.9), 7.9 (5.7-11.0), 8.0 (5.1-12.1) and 12.9 (6.4-19.4) cmH2O/L in prone from 20 to 5 cmH2O PEEP (P=0.06 for PEEP and P=0.06 for position). Dorsal R2,L significantly and positively correlated with amount of collapse measured with EIT. Global and regional lung and chest wall viscoelastic parameters can be described by a simple rheological model. Regional E2 and R2 were uninfluenced by PEEP and position except for PEEP on dorsal E2,L and position on dorsal E2,cw.

scholarly journals Dynamics of regional lung aeration determined by electrical impedance tomography in patients with acute respiratory distress syndrome

2012 ◽  
Vol 7 ◽  
Author(s):  
Sven Pulletz ◽  
Matthias Kott ◽  
Gunnar Elke ◽  
Dirk Schädler ◽  
Barbara Vogt ◽  
...  
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Distress Syndrome ◽  
Impedance Tomography ◽  
Time Constants ◽  
Lung Aeration ◽  
Regional Lung

Background: Lung tissue of patients with acute respiratory distress syndrome (ARDS) is heterogeneously damaged and prone to develop atelectasis. During inflation, atelectatic regions may exhibit alveolar recruitment accompanied by prolonged filling with air in contrast to regions with already open alveoli with a fast increase in regional aeration. During deflation, derecruitment of injured regions is possible with ongoing loss in regional aeration. The aim of our study was to assess the dynamics of regional lung aeration in mechanically ventilated patients with ARDS and its dependency on positive end-expiratory pressure (PEEP) using electrical impedance tomography (EIT). Methods: Twelve lung healthy and twenty ARDS patients were examined by EIT during sustained step increases in airway pressure from 0, 8 and 15 cm H2O to 35 cm H2O and during subsequent step decrease to the corresponding PEEP. Regional EIT waveforms in the ventral and dorsal lung regions were fitted to bi-exponential equations. Regional fast and slow respiratory time constants and the sizes of the fast and slow compartments were subsequently calculated. Results: ARDS patients exhibited significantly lower fast and slow time constants than the lung healthy patients in ventral and dorsal regions. The time constants were significantly affected by PEEP and differed between the regions. The size of the fast compartment was significantly lower in ARDS patients than in patients with healthy lung under all studied conditions. Conclusion: These results show that regional lung mechanics can be assessed by EIT. They reflect the lower respiratory system compliance of injured lungs and imply more pronounced regional recruitment and derecruitment in ARDS patients.

Regional lung volume changes in children with acute respiratory distress syndrome during a derecruitment maneuver*

2007 ◽  
Vol 35 (8) ◽  
pp. 1972-1978 ◽  
Author(s):  
Gerhard K. Wolf ◽  
Bartlomiej Grychtol ◽  
Inez Frerichs ◽  
Huibert R. van Genderingen ◽  
David Zurakowski ◽  
...  
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Lung Volume ◽  
Distress Syndrome ◽  
Volume Changes ◽  
Regional Lung
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