THE ASSESSMENT OF NEURO-MECHANICS OF INSPIRATORY MUSCLES DURING MECHANICAL VENTILATION

Abstract

ABSTRACT The decline in inspiratory muscles function for patients undergoing mechanical ventilation may further extend the duration of mechanical ventilation leading to lethal complications. Thus, the assessment of neuro-mechanics of inspiratory muscles may help us understand the pathophysiology for mechanical ventilation failure to avoid its complications. In this dissertation, we assessed the characteristics of inspiratory neuro-mechanics under different conditions. This dissertation is reported in three different papers. In the first paper, we sought to assess the quality of the available literate that used surface EMG of extra-diaphragmatic muscles during invasive mechanical ventilation. We demonstrated that the use of sEMG of extra-diaphragmatic muscle is a valid tool to assess mechanical loading/unloading of respiratory muscles and respiratory drive or sensation. However, the quality of literature was considered to have a high and unclear risk of bias. In the second paper, we investigated the neuro-mechanics of inspiratory muscles after progressive airway resistance in healthy adults. Neuromechanical efficiency of the diaphragm increased while neuro- was not different. The restoration of mechanical output was immediate and was accompanied with improved neuro-mechanical efficiency of the diaphragm while extra-diaphragmatic muscles were not major players in inspiratory force production under conditions where diaphragmatic capacity is maintained. In the third paper, we assessed neuromechanical characteristics of inspiratory muscles in patients undergoing mechanical ventilation. Diaphragmatic neuromechanical efficiency was significantly lower in the mechanical ventilation liberation failure group. However, neuromechanical efficiency of extra-diaphragmatic muscles was not significantly different between the two groups. We concluded that reduced neuromechanical efficiency of the diaphragm is a major characteristic of mechanical ventilation liberation failure. Future research should focus on the benefits of assessing respiratory neuro-mechanics to determine mechanical ventilation status in patients with high risk of weaning failure. Researchers should test the accuracy of sEMG for evaluating respiratory neuro-mechanics as an assessment tool during mechanical ventilation and when the diaphragm is severely dysfunctional or injured. mechanical efficiency of extra-diaphragmatic muscles