Pathophysiologie und Diagnostik

Zusammenfassung

Künstliche Beatmung kann das Lungengewebe in Abhängigkeit von Beatmungseinstellungen (Druckamplitude, endexspiratorischer Druck, Frequenz) und Beatmungsdauer schädigen. Insbesondere in den inhomogen geschädigten Lungen von ARDS–Patienten führt alveoläre Überdehnung zum Volutrauma, zyklisches Öffnen und Schließen der Alveolen zum Atelektotrauma. Von besonderer Bedeutung ist wohl, dass diese Vorgänge auch zum Biotrauma, das heißt zu einer beatmungsinduzierten Überaktivierung der pulmonalen Entzündungsantwort führen können. Diese Probleme sind bei der derzeit empfohlenen Beatmung mit 6ml/kg idealisiertes Körpergewicht vermindert, aber nicht eliminiert. Eine Beatmungsoptimierung mit dem Ziel der Reduktion beatmungsassoziierter Lungenschäden kann in Zukunft hoffentlich erzielt werden durch die Überwachung atemmechanischer Messgrößen, wie Stress–Index und Slice–Methode, und durch die bettseitige Anwendung neuer echtzeitfähiger bildgebender Verfahren wie der elektrischen Impedanztomographie.

Summary

Mechanical ventilation may lead to lung injury depending on the ventilatory settings (e.g. pressure amplitudes, endexpiratory pressures, frequency) and the length of mechanical ventilation. Particularly in the inhomogeneously injured lungs of ARDS patients, alveolar overextension results in volutrauma, cyclic opening and closure of alveolar units in atelectrauma. Particularly important appears to be the fact that these processes may also cause biotrauma, i.e. the ventilator–induced hyperactivation of inflammatory responses in the lung. These side effects are reduced, but not eliminated with the currently recommended ventilation strategy with a tidal volume of 6ml/kg idealized body weight. It is our hope that in the future optimization of ventilator settings will be facilated by bedside monitoring of novel indices of respiratory mechanics such as the stress index or the Slice technique, and by innovative real–time imaging technologies such as electrical impedance tomography.

Lungenprotektive Beatmung - beatmungsbedingte Lungenschädigung - Biotrauma - Monitoring

Lung protective ventilation - ventilator–induced lung injury - biotrauma - monitoring

Kernaussagen

• Beatmungsinduzierte Lungenschädigung ist bei der derzeit empfohlenen Beatmung mit 6ml/kg idealisiertes Körpergewicht vermindert, aber nicht eliminiert.

• Alveoläre Überdehnung kann zum Volutrauma, zyklisches Öffnen und Schließen der Alveolen zum Alektotrauma führen. Ein Biotrauma kann infolge beatmungsinduzierter Überaktivierung der pulmonären Entzündungsantwort entstehen.

• Überwachung von beatmeten Patienten ist z.Zt. nicht optimal.

• Beatmungseinstellungen müssen individuell anhand von Messgrößen unterschiedlicher Monitoringverfahren definiert werden.

• Zu den Standardverfahren zählen die Ermittlung von respiratorischen und atemmechanischen Messgrößen sowie klassische bildgebende Verfahren.

• Neue Methoden (z.B. EIT, Stress–Index– und Slice–Methode) könnten in der Zukunft bettseitig und kontinuierlich Informationen liefern, mit denen die Beatmungseinstellungen optimiert werden können.

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