The missed side of breathing. The importance of monitoring and assisting expiration during mechanical ventilation to avoid ventilator induced lung injury.

Bakgrund:

Mechanical ventilation is a life-saving supportive therapy for patients admitted to intensive care. However, despite substantial technological progress, the risk for ventilator-induced lung injury remain high.

The assumption that expiration is passive and non-harmful led to almost completely disregard the expiratory phase during mechanical ventilation. However, patency of distal airways during expiration is of crucial importance in injured heterogeneous lungs. Lung collapse characterizing expiration lead to a gradual compression of peripheral airways throughout the expiration.

This phenomenon is known as expiratory flow limitation (EFL) and has been recognized as cause of major respiratory complications and increased mortality in critical care patients.

Our previous studies have showed that the diaphragm is an important regulator of expiration during spontaneous breathing and that the expiratory brake produced by an expiratory diaphragmatic contraction or by an external expiratory resistor can reduce work of breathing and improve lung mechanics in an experimental model of acute respiratory failure.

Målsättning:

Main purpose of the present research project will be to explore the effects of expiratory modulation in mechanically ventilated critically ill subjects. Arbetsplan:

We planned to perform clinical observational studies aiming at investigating potential factors interfering with the modulation of the expiratory phase in mechanically ventilated critical care patients. We will focus on the expiratory consequences of: - critical care acquired muscle weakness, - fluid overload,

- acute cerebrovascular events and - central hypoventilation caused by traumatic cervical spinal cord injury. At the same time, experimental studies will be also performed in order to: - access the inflammatory pathway characterizing mechanical ventilation with and without expiratory modulation;

- develop a closed-loop-modulation of the expiratory resistance, adjusted depending on the intrinsic characteristics of the respiratory mechanics. Betydelse:

The current research project is finalized to a more protective mechanical ventilation, a shorter time on the ventilator and fewer days in intensive care. In the long run, we expect to positively influence patients’ survival.