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Pharyngeal occlusion during obstructive apnea is thought to be an inspiratory-related event; however, occlusion also occurs in the absence of negative intrathoracic pressure. We hypothesized that inspiratory-related pharyngeal occlusion would be preceded by significant expiratory narrowing. Eight sleeping patients with obstructive apnea were studied.(More)
RATIONALE Although cognitive deficits are well documented in patients with sleep apnea, the impact on memory remains unclear. OBJECTIVES To test the hypotheses that (1) patients with obstructive sleep apnea have memory impairment and (2) memory impairment is commensurate with disease severity. METHODS Patients with obstructive sleep apnea and healthy(More)
RATIONALE Obesity increases the risk and severity of sleep-disordered breathing. The degree to which excess body weight contributes to blood oxygen desaturation during hypopneic and apneic events has not been comprehensively characterized. OBJECTIVES To quantify the association between excess body weight and oxygen desaturation during sleep-disordered(More)
BACKGROUND Congestive heart failure (CHF) patients often present with obstructive and central sleep apnea occurring concurrently within the same night. This study assessed the efficacy of, and improvements associated with, the use of adaptive servo-ventilation (ASV) in CHF patients with all types of sleep apnea. We hypothesized that ASV would be effective(More)
Control of breathing was studied in a patient with a lesion in the ventral pons; no volitional behaviour, including voluntary breathing acts, was possible (locked-in syndrome, LIS). Spontaneous breathing via a tracheostomy maintained a normal PETCO2 of 39-40 mmHg. Variability of ventilatory parameters awake was similar to that seen in five tracheostomized(More)
Inspiratory activation of the genioglossus (GG) may occur by central drive or as a reflex to negative airway pressure. To distinguish between these, we studied seven laryngectomy patients who breathe via tracheal stomas. Negative pressure stimuli (-15 and -25 cmH2O for 500 ms) were applied 1) at functional residual capacity and 2) during early inspiration(More)
We have studied post-hyperventilation breathing pattern in eight, awake, healthy, naive volunteers after 5 min voluntary or mechanical hyperventilation during normocapnia (PETCO2 = 38 mmHg) and 'hypocapnia (24 mmHg). Breathing was monitored for 10 min post-hyperventilation, 'non-invasively', using calibrated respiratory inductance plethysmography;(More)
OBJECTIVE Obstructive sleep apnea (OSA) causes hypoxemia and fragmented sleep, which lead to neurocognitive deficits. We hypothesised that focal loss of cortical gray matter generally within areas associated with memory processing and learning and specifically within the hippocampus would occur in OSA. METHODS Voxel-based morphometry, an automated(More)
The present study was designed to determine the effect of sleep on reflex pharyngeal dilator muscle activation by stimuli of negative airway pressure in human subjects. Intra-oral bipolar surface electrodes were used to record genioglossus electromyogram (EMG) responses to 500 ms duration pressure stimuli of 0 and -25 cmH2O applied, via a face-mask, in four(More)
The objective of this study was to determine the efficacy of gabapentin as adjunctive therapy in doses required to achieve the most effective seizure control. There were 2016 patients with partial seizures requiring adjunctive therapy who received gabapentin at doses up to 3600 mg/day in this open-label, multicenter, 16-week study. Of the 1055 patients(More)