Christopher J Worsnop

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A common clinical dilemma faced by sleep physicians is in deciding the level of severity at which patients with obstructive sleep apnea (OSA) should be treated. There is particular uncertainty about the need for, and the effectiveness of, treatment in mild cases. To help define the role of nasal continuous positive airway pressure (CPAP) treatment in mild(More)
Ventilation decreases at sleep onset. This change is initiated abruptly at alpha-theta electroencephalographic transitions. The aim of this study was to determine the contributions of reduced activity in respiratory pump muscles and upper airway dilator muscles to this change. Surface electromyograms over the diaphragm (Di) and intercostal muscles and(More)
BACKGROUND Reduced upper airway muscle activity during sleep is fundamental to obstructive sleep apnea (OSA) pathogenesis. Hypoglossal nerve stimulation (HGNS) counteracts this problem, with potential to reduce OSA severity. STUDY OBJECTIVES To examine safety and efficacy of a novel HGNS system (HGNS, Apnex Medical, Inc.) in treating OSA. PARTICIPANTS(More)
Arousal from sleep is associated with elevated cardiac and respiratory activity. It is unclear whether this occurs because of homeostatic mechanisms or a reflex activation response associated with arousal. Cardiorespiratory activity was measured during spontaneous arousals from sleep in subjects breathing passively on a ventilator. Under such conditions,(More)
STUDY OBJECTIVES Multiunit electromyogram recordings of genioglossus have demonstrated an abrupt reduction in the muscle's activity at sleep onset. Recent evidence from single motor unit recordings indicates that the human genioglossus muscle consists of motor units with a variety of discharge patterns. The aim of the present study was to determine the(More)
In normal young men, there is an abrupt fall in ventilation (VE), a rise in upper airway resistance (UAR), and falls in the activities of the diaphragm (Di), intercostals (IC), genioglossus (GG), and tensor palatini (TP) at sleep onset. On waking, there is an abrupt increase in VE and fall in UAR and an increase in the activities of Di, IC, GG, and TP. The(More)
1. The upper airway not only provides a passage for air to be breathed in and out of the lungs, but it also heats, humidifies and filters the air and is involved in cough, swallowing and speech. 2. The complex muscle structure of the upper airway that produces speech and swallowing in humans also modulates respiratory airflow throughout the respiratory(More)
Ginseng alone or combined with other herbs has been increasingly used for chronic obstructive pulmonary disease (COPD). This review aims to evaluate the effectiveness and safety of oral Ginseng formulae for stable COPD. Four English databases and three Chinese databases were searched to identify randomized controlled trials. Methodological quality was(More)
BACKGROUND AND OBJECTIVE Topical lidocaine is often administered through the flexible bronchoscope in an attempt to reduce excessive coughing and patient discomfort. With the increasing use of sedation, including opiates that possess central cough suppressant effects, and the potential for serious clinical toxicity, the need for evidence regarding the(More)
OBJECTIVE To determine if topical 4% amethocaine gel can reduce the pain associated with arterial punctures. DESIGN Randomized, placebo-controlled, double-blinded trial with parallel groups. SETTING Teaching hospital. PATIENTS Adults requiring arterial punctures for blood gas estimation as part of routine care. INTERVENTIONS Four percent amethocaine(More)