Michael J . Brennick

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To better understand pharyngeal airway mechanics as it relates to the pathogenesis and treatment of obstructive sleep apnoea, we have developed a novel application of magnetic resonance imaging (MRI) with non-invasive tissue tagging to measure pharyngeal wall tissue motion during active dilatation of the airway. Eleven anaesthetized Sprague-Dawley rats were(More)
RATIONALE Although obstructive sleep apnea is strongly associated with obesity, we have little understanding of how obesity may alter the mechanical properties of the pharynx and the role of obesity in the pathogenesis of sleep apnea. OBJECTIVES The overall objective of this study was to determine the effect of obesity on pharyngeal airway size and(More)
To examine the regional mechanical effects of selective genioglossus muscle activation on pharyngeal airway size and function, magnetic resonance images of the pharyngeal airway were obtained in five paralyzed, anesthetized cats over a range of positive and negative pressures in an isolated, sealed upper airway. When all results across pressure levels and(More)
Upper airway compliance indicates the potential of the airway to collapse and is relevant to the pathogenesis of obstructive sleep apnea. We hypothesized that compliance would vary over the rostral-to-caudal extent of the pharyngeal airway. In a paralyzed isolated upper airway preparation in cats, we controlled static upper airway pressure during magnetic(More)
RATIONALE The effect of obesity on upper airway soft tissue structure and size was examined in the New Zealand Obese (NZO) mouse and in a control lean mouse, the New Zealand White (NZW). OBJECTIVES We hypothesized that the NZO mouse has increased volume of neck fat and upper airway soft tissues and decreased pharyngeal airway caliber. METHODS Pharyngeal(More)
Fiberoptic imaging in an isolated, sealed upper airway was performed in 10 decerebrate cats to determine the effect of pharyngeal muscle activation on airway pressure-area relationships. Bilateral cuff electrodes stimulated the distal cut ends of the following nerves: medial and lateral hypoglossus, glossopharyngeus, and pharyngeal branch of vagus. At given(More)
UNLABELLED Obesity is an important risk factor for pharyngeal airway collapse in obstructive sleep apnea (OSA). To examine the effect of obesity on pharyngeal airway size on inspiration and expiration, respiratory-gated MRI of the pharynx was compared in New Zealand obese (NZO) and New Zealand white (NZW) mice (weights: 50.4g vs. 34.7g, p<0.0001). RESULTS(More)
The medial branch (Med) of the hypoglossal nerve innervates the tongue protrudor muscles, whereas the lateral branch (Lat) innervates tongue retractor muscles. Our previous finding that pharyngeal airflow increased during either selective Med stimulation or whole hypoglossal nerve (WHL) stimulation (coactivation of protrudor and retractor muscles) led us to(More)
The genioglossus is an upper airway dilator muscle, the length of which is directly related to patency in the oropharyngeal region. We hypothesized that genioglossal length (Lgg) is dynamically influenced by the afterload exerted by negative upper airway pressure during inspiration and by the intrinsic length-tension characteristics of the muscle (preload).(More)
This study presents a new computational system for modeling the upper airway in rats that combines tagged magnetic resonance imaging (MRI) with tissue material properties to predict three-dimensional (3D) airway motion. The model is capable of predicting airway wall and tissue deformation under airway pressure loading up to airway collapse. The model(More)