Assessment of regional lung recruitment and derecruitment during a PEEP trial based on electrical impedance tomography
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To investigate whether electrical impedance tomography (EIT) is capable of monitoring regional lung recruitment and lung collapse during a positive end-expiratory pressure (PEEP) trial.
Experimental animal study of acute lung injury.
Six pigs with saline-lavage-induced acute lung injury.
An incremental and decremental PEEP trial at ten pressure levels was performed. Ventilatory, gas exchange, and hemodynamic parameters were automatically recorded. EIT and computed tomography (CT) scans of the same slice were simultaneously taken at each PEEP level.
Measurements and results
A significant correlation between EIT and CT analyses of end-expiratory gas volumes (r = 0.98 up to 0.99) and tidal volumes (r = 0.55 up to r = 0.88) could be demonstrated. Changes in global and regional tidal volumes and arterial oxygenation (PaO2/FiO2) demonstrated recruitment/derecruitment during the trial, but at different onsets. During the decremental trial, derecruitment first occurred in dependent lung areas. This was indicated by lowered regional tidal volumes measured in this area and by a decrease of PaO2/FiO2. At the same time, the global tidal volume still continued to increase, because the increase of ventilation of the non-dependent areas was higher than the loss in the dependent areas. This indicates that opposing regional changes might cancel each other out when combined in a global parameter.
EIT is suitable for monitoring the dynamic effects of PEEP variations on the regional change of tidal volume. It is superior to global ventilation parameters in assessing the beginning of alveolar recruitment and lung collapse.
KeywordsElectrical impedance tomography Computed tomography Acute lung injury Lung recruitment Positive end-expiratory pressure
The support of Eckhard Teschner, Dräger Medical AG, is gratefully acknowledged.
- 14.Victorino JA, Borges JB, Okamoto VN, Matos GF, Tucci MR, Caramez MP, Tanaka H, Sipmann FS, Santos DC, Barbas CS, Carvalho CR, Amato MB (2004) Imbalances in regional lung ventilation: a validation study on electrical impedance tomography. Am J Respir Crit Care Med 169:791–800PubMedCrossRefGoogle Scholar
- 17.Odenstedt H, Lindgren S, Olegard C, Erlandsson K, Lethvall S, Aneman A, Stenqvist O, Lundin S (2005) Slow moderate pressure recruitment maneuver minimizes negative circulatory and lung mechanic side effects: evaluation of recruitment maneuvers using electric impedance tomography. Intensive Care Med 31:1706–1714PubMedCrossRefGoogle Scholar
- 20.Meier T, Luepschen H, Karsten J, Großherr M, Leibecke T, Gehring H, Leonhardt S (2006) Impact of different PEEP levels on regional compliance measured by electrical impedance tomography. Intensive Care Med [Suppl] 32(13):S221Google Scholar