Diaphragm Pacing during Mechanical Ventilation: Development of a Control Algorithm and Analysis of Respiratory Mechanics

Prolonged totally controlled mechanical ventilation results in the complete absence of mechanical activity of the diaphragm leading to rapid loses in diaphragmatic function, a syndrome known as Ventilator-Induced Diaphragmatic Dysfunction VIDD. Electrical activation of the diaphragm by phrenic nerve stimulation may prevent diaphragm atrophy in sedated patients undergoing Controlled Mechanical Ventilation CMV. The aims of this thesis were to develop a control algorithm to pace the diaphragm in-synchrony with a ventilator during controlled mechanical ventilation in critically-ill patients and analyze the respiratory mechanics resulting from such co-ordinated inspiratory action of the diaphragm and the mechanical ventilator. The algorithm was verified through bench tests and evaluated in an animal model. In the animal study, the respiratory mechanics were also analyzed to better understand the effects of synchronous diaphragm pacing during mechanical ventilation and to identify an optimal level of pacing support during mechanical ventilation for clinical applications.