 On the basis of this theory, any factor or disease that would increase pulmonary vascular pressures (e.g.hypervolaemia) or increase the magnitude of the negative pressures in the lung during inspiration (e.g.dynamic upper airway obstruction) would increase the severity of EIPH; however neither experimentally induced laryngeal hemiplegia nor dorsal displacement of the soft palate increase pulmonary capillary transmural pressure.