Bedside imaging monitoring techniques in invasively ventilated patients

Invasive mechanical ventilation is a life-sustaining modality routinely used to support the respiratory function of critically ill patients. The positive pressure applied by mechanical ventilators to the conducting airways and alveoli can damage the lung tissue (‘barotrauma’) and can have significant hemodynamic effects by increasing intrathoracic pressures. Bedside imaging techniques can be used to visualize lung morphology and evaluate lung aeration and hemodynamic effects invasive ventilation. This thesis is a collection of investigations focusing on evaluating lung and heart function through bedside available imaging technics, including lung ultrasound, electrical impedance tomography and transthoracic echocardiography, in invasively ventilated critically ill patients. The results of this thesis show that these three commonly available bedside imaging technics can be used to identify patients with different lung morphologies, assess pulmonary edema, which is related to patient outcomes and can be used to evaluate lung overdistention and right ventricular failure during invasive ventilation. Each could earn a place in clinical practice when applied in the right patient category and combined with an easily applicable and consistent system of interpreting results. In patients with ARDS, LUS can be used to identify lung morphology and severity of lung aeration decrease. EIT is suitable for monitoring aeration changes and homogeneity of ventilation, particularly when patients are placed in prone position. Right ventricular myocardial performance index obtained through transthoracic echocardiography can be used for monitoring right heart function in invasively ventilated patients. Findings of this thesis can be used for the design of future studies related to invasive ventilation.