Diaphragm Structure and Pathobiology in Patients Being Bridged to Lung Transplant

Mechanical ventilation has been linked to diaphragm injury and dysfunction. During mechanical ventilation, the amount of breathing work done by the diaphragm is unpredictable: the diaphragm could be completely rested, or it could be overworked. Either of these possibilities may cause injury to the diaphragm. Patients with an injured and dysfunctional diaphragm have greater difficulty weaning from mechanical ventilation - they become too weak to breathe. However, little is known about the relationship between changes in the diaphragm and the histological (structure of cells and tissue) basis of these changes. The investigators have developed a new technique employing beside ultrasound to measure diaphragm thickness. This allows them to observe changes in diaphragm muscle structure and function.

The goal of the study is to determine whether different forms of respiratory support (mechanical ventilation vs extracorporeal life support) lead to different degrees of diaphragm injury and to compare changes in the diaphragm seen on ultrasound to changes in the diaphragm tissues under a microscope. This will help the investigators to confirm the best way to avoid diaphragm injury and to understanding the meaning of diaphragm ultrasound images.