In order to determine the ability of single-breath nitrogen closing volume (CV) to detect early airway obstruction, the CV was measured in patients with either minimal obstruction of spirometry or with increased residual volume (RV). A total of 39 subjects was included in this study. The mean CV was largest in patients who had reduced maximum mid-expiratory flow rates (MMF). There was no differ...

We evaluated the effects of the rate and volume of tidal ventilation on airway resistance (Raw) during intravenous methacholine (MCh) challenge in mechanically ventilated rabbits. Five rabbits were challenged at tidal volumes of 5, 10, and 20 ml/kg at a frequency of 15 breaths/min and also under static conditions (0 ml/kg tidal volume). Four rabbits were subjected to MCh challenge at frequencie...

INTRODUCTION I-gel is a relatively new supra-glotitc airway device which is claimed to be superior to laryngeal mask airway. It can be used ingeneral anesthesia with spontaneous ventilation as well as with positive pressure ventilation.This study was designed to assess whether I-gel creates adequate laryngeal seal during positive pressure ventilation in patients undergoing laparoscopic surgery....

BACKGROUND The mechanisms by which mandibular advancement splints (MAS) improve obstructive sleep apnoea (OSA) are not well understood. This study aimed to evaluate the mechanism of action of MAS by assessing their effect on upper airway structure in patients with OSA. METHODS Patients were recruited from a sleep disorders clinic for treatment with a custom-made MAS. MRI of the upper airway w...

THE PHARYNGEAL AIRWAY IS A complicated structure combining soft tissue and boney elements that make it prone to collapse when neuromuscular activity wanes during sleep. Anatomic structures form a pliable conduit capable of changing airway patency dynamically to support its respiratory, alimentary, and vocal functions. Respiratory function is supported by active neuromuscular and passive structu...

In this study, to clarify the influence of the maxillo-mandibular bones and cranium on airway morphology, maxillo-facial morphology in patients with jaw deformation was measured using cephalograms and X-ray CT imaging data. Subjects consisted of 25 adult women in whom cephalograms and X-ray CT were taken to diagnose jaw deformation. The data obtained were classified based on skeletal and facial...

BACKGROUND Lateral positioning decreases upper airway obstruction in paralyzed, anesthetized adults and in individuals with sleep apnea during sleep. The authors hypothesized that lateral positioning increases upper airway cross-sectional area and total upper airway volume when compared with the supine position in sedated, spontaneously breathing children. METHODS Children aged 2-12 yr requir...

Although airway patency is partially maintained by parenchymal tethering, this structural support is often ignored in many discussions of asthma. However, agonists that induce smooth muscle contraction also stiffen the parenchyma, so such parenchymal stiffening may serve as a defense mechanism to prevent airway narrowing or closure. To quantify this effect, specifically how changes in parenchym...

nasal mucosa has an extraordinary nerve supply with unique geometry that encompasses complex physiology. among these, side-specific predilections to the respiratory and autonomic centers are the interesting issues that have been raised about the consequences of the nasal irritations. the aim of the study was an evaluation of how intranasal stimulation influences lung mechanics and determines wh...

Increasing lung volume increases upper airway patency and decreases airway resistance and collapsibility. The role of diaphragm contraction in producing these changes remains unclear. This study was undertaken to determine the effect of selective diaphragm contraction, induced by phrenic nerve stimulation, on upper airway collapsibility and the extent to which any observed change was attributab...