[The open lung concept. Clinical application in severe thoracic trauma]

Abstract

Introduction: The pathomorphological substratum of the pulmonary contusion is a parenchymatous hemorrhage followed by interstitial and alveolar edema, finally resulting in a severe damage of the surfactant system. The pathophysiological consequence is an imbalance between ventilation and perfusion, which causes the clinical finding of hypoxia.

Methods: Between December 1997 and December 2000, we treated 32 polytraumatized patients (ISS 43, PTS 32) additionally suffering from severe chest contusion (AIS 5, PTST 14), by ventilation according to the Open Lung Concept (OLC). The initial disturbance of oxygenation was shown by a mean paO2/FIO2-ratio of 134 (96;181) mmHg. The OLC recruits atelectatic lung areas by the application of a defined temporary positive inspiratory pressure (PIP), which is called the "opening pressure". The recruited lung areas were kept open by high total-PEEP.

Results: For the recruitment procedure, a mean PIP of 65 (51;65) mbar was required. Recruited alveoli were kept open by a total-PEEP of 22 (20;23) mbar. The paO2/FIO2-ratio increased significantly (P < 0.001) from 134 (96;181) to 522 (433;587) mmHg. After the recruitment procedure, we could reduce PIP and FIO2. In spite of the minimal tidal volumes of 3.5 (3.0;3.9) ml per kg bodyweight by which our patients were ventilated, the levels of oxygenation and normocapnia could be maintained. There were no evidences for side-effects like perfusion impairment. Two patients (6.25%) died of extrapulmonary causes.

Conclusion: Ventilation according to the OLC seems to be a highly effective treatment of ventilation-perfusion-impairment following pulmonary contusion. Minimal tidal volumes and the low PIP-levels after the recruitment procedure meet the demands of a lung-protective Low-Tidalvolume-Ventilation.