Browsing by Author "Leguillette, Renaud"
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- ItemOpen AccessEvaluation of suitable reference genes for gene expression studies in bronchoalveolar lavage cells from horses with inflammatory airway disease(BioMed Central, 2011-01-28) Beekman, Laura; Tohver, Triin; Dardari, Rkia; Leguillette, Renaud
- ItemOpen AccessNeural Respiratory Drive and Respiratory Muscle Function During CO2 Stimulation(2022-06-15) Tagliabue, Giovanni; Easton, Paul Alexander; Zuege, Danny J.; Leguillette, Renaud; Day, TrevorBackground. The use of EMG of the respiratory muscles as a surrogate of the central neural respiratory drive is gaining clinical popularity. Currently, the clinical EMG recording of the crural diaphragm by an esophageal electrodes probe (EAdi) is promoted as a “gold standard”. Additionally, other inspiratory muscles have been investigated as a less invasive alternative, especially the surface EMG of parasternal intercostal. Now there is major clinical interest focusing on the EMG of abdominal muscle as indicator of diaphragm weakness. However, all these clinical applications rely on physiological and technical assumptions that are not fully elucidated. Theme. The focus of this thesis is to address the following questions: 1) do crural and costal diaphragm share an identical neural-mechanical profile during inspiration? 2) does crural and costal diaphragm activity extend into, and contribute identically, during expiration? 3) does the parasternal intercostal share a similar neural activation with the diaphragm during inspiration? 4) is the current clinical technique, recording the surface EMG of parasternal intercostal? 5) is the expiratory phase a passive physiologic process, so that the activation of the abdominal muscles is a pathological indicator? Projects. This thesis is organized as a series of related projects, corresponding to individual chapters addressing each physiological question. The successful execution of this thesis work relied upon a model of a large, normal, intact mammals group, with intact airways, awake without anesthetic, at rest during spontaneous breathing. And, we did further measurements during progressive chemical stimulation by hypercapnia. Summary. We found that the crural and costal diaphragm each exhibit a distinct neural mechanical profile during inspiration, and the differentiation in their operational role extends into the early phase of expiration. Therefore, the clinical assumption that the crural diaphragm is representative of the whole diaphragm is not supported. Our results support the use of parasternal intercostal as a surrogate of neural respiratory drive. However, we confirmed that the current technique based on surface EMG is not reliable due to intrinsic physiologic limitations. Finally, our findings reinforce the concept that expiration is not a passive process but actively contributes to inspiration.
- ItemOpen AccessRespiratory Muscle Function with Agonists(2016-01-29) Suneby Jagers, Jenny Vannessa; Easton, Paul ALexander; Giles, Wayne; Hussain, Sabah; Leguillette, RenaudRespiratory muscle agonists of pharmaceutical or chemical nature can be used to alter breathing. Pharmaceutical respiratory agonists can be significant to those suffering from pulmonary diseases such as chronic obstructive pulmonary disease (COPD). In this thesis pharmacological agonists such as aminophylline, salmeterol and vilanterol trifenatate/fluticasone furoate have been shown to work to improve respiration through improved respiratory muscle action. Measurements are made directly from the muscle, ushering in a new era of more direct and useable measurement techniques. Chemical agonists such as hypercapnia (high CO2) and hypoxia (low oxygen) can elicit changes in respiration and are used to elucidate and isolate the action of the pharmaceutical agonists. Respiratory measurements, like those taken in spirometery or pulmonary function tests, can tell us much about the condition of our respiratory system. It has long been assumed that functional residual capacity (FRC) is an “at rest” position for the respiratory system. A case study, included in this thesis, sheds light on this variable and challenges our views on “rest” within the respiratory system. The respiratory muscles may contain a basal level of tone, or foreshortening, shown after flaccid paralysis using sonomicrometry. Physiological data, both in its collection and analysis, requires skill and great care as to avoid bias and to maintain integrity and honesty in its reporting. The analysis process from beginning to end is a cornerstone of this research and mastery of its use is demonstrated throughout this thesis.