Lung- and Respiratory Muscle-Protective Mechanical Ventilation: From Physiology to Clinical Applications

The respiratory muscles are of critical importance for the recovery of critically ill patients after recieving mechanical ventilation in the Intensive Care unit. Sadly, many patients will develop respiratory muscle dysfunction during their admittance. In this thesis, we focus on techniques to monitor activity of the respiratory muscles during mechanical ventilation, with a long-term aim of preventing both underuse and overactivity of the respiratory muscles. This has to be balanced with lung-protective ventilation, which aims to prevent harm to the lungs by lowering the energy transmitted to the lung tissue. Part one of this thesis focusses on monitoring and controlling lung stress and diaphragm effort in critically ill patients. The general hypothesis of this part of thesis was that respiratory drive and respiratory muscle effort can be measured and controlled in critically ill patients by understanding respiratory physiology. Part two of this thesis focusses on the expiratory muscles, the often-neglected part of the respiratory muscle pump, and on the expiratory phase of respiration. The general aim of this part of the thesis was to evaluate how critically ill patients use their expiratory muscles, and whether the function of the expiratory muscles change during their ICU admission. The general hypothesis was that the expiratory muscles should not be ignored when considering a new approach to ventilation aimed at protecting the respiratory muscle pump.