Erhalt der Spontanatmung beim ARDS – Zwischen Muskelrelaxierung und Zwerchfellprotektion

The concept of lung protective ventilation is based on the application of low tidal volumes of 5 - 6 ml/kg predicted body weight and low inspiratory plateau pressures of ≤ 30 cmH2O. The aim of this strategy is not only to avoid lung injury induced by mechanical ventilation but also to minimise ventilation-induced diaphragmatic myotrauma which is associated with increased morbidity and mortality. Ventilation-induced diaphragmatic dysfunction is caused by a variety of pathogenetic mechanism such as atrophy of diaphragmatic myofibrils due to proteolytic pathways, load-induced muscle injury and oxidative stress with inflammatory reactions resulting in diaphragmatic weakness and consecutive prolonged weaning. These deleterious changes in the diaphragm are established within 2 - 3 days after initiating mechanical ventilation and the degree of diaphragm injury is correlated with the duration of mechanical ventilation. Low levels of muscle activity seem to be sufficient to prevent mitochondrial myofibrillar dysfunction. A diaphragmprotective mechanical ventilation strategy is a new concept based on targeting appropriate levels of respiratory effort, avoiding the harmful effects of both excessive and insufficient inspiratory effort. Oesophageal manometry by measuring the oesophageal pressure swing and diaphragm ultrasound by measuring the diaphragm thickening fraction are applicable tools to monitor the respiratory effort in mechanically ventilated patients.