Effects of mechanical ventilation on diaphragm function in patients and in different animal models.

In ventilated patients, difficulties in discontinuing ventilatory support are frequent, time consuming, and remain a serious problem. Data in animal studies have consistently shown that mechanical ventilation induced rapid reduction in diaphragm force and caused atrophy. The aims of the present project are: 1) to examine the effects of controlled mechanical vantilation in animals with already diseased diaphragms and to elucidate the time course of diaphragm function recovery after mechanical ventilation in healthy and diseased diaphragms; 2) to examine the effects of neurally adjusted ventilatory assist (NAVA) on loss and recovery of diaphragmatic function in critically ill patients. The first issue will be addressed in septic rats and COPD-like rats using our animal model of mechanical ventilation. The second issue will be addressed in critically ill patients receiving conventional ventilation or NAVA. Evolution of diaphragm force will be measured while assessing twitch transdiaphragmatic pressure using bilateral anterior magnetic phrenic nerve stimulation. This project will allow us 1) to determine whether mechanical ventilation is more detrimental in a weak diaphragm and how long it takes for the diaphragm to recover normal function; 2) to unravel whether NAVA in critically ill patients may better preserve diaphragmatic force compared with conventional ventilation.

Keywords:Mechanical ventilation, Phrenic nerve stimulation, Recovery, COPD, Sepsis, NAVA, Diaphragm function

Disciplines:Physiology, Respiratory medicine, Orthopaedics