Robert P. Schnall

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BACKGROUND Abnormalities in pulse wave amplitude (PWA) have been described in subjects with atherosclerosis and may be a marker of future cardiac events. We evaluated the relationship between changes in PWA of the finger and peripheral endothelial function. METHODS We performed measurements of PWA with a novel finger plethysmograph (peripheral arterial(More)
BACKGROUND Diagnosis of obstructive sleep apnea syndrome (OSAS) by ambulatory systems is a growing practice in view of the large number of patients awaiting correct diagnosis. The Watch PAT100 (WP100) [Itamar Medical; Caesarea, Israel] is a portable device based on the peripheral arterial tone (PAT) signal, and is designed for unattended home sleep studies.(More)
OBJECTIVES The goal of this study was to examine the effect of enhanced external counterpulsation (EECP) on endothelial function. BACKGROUND Enhanced external counterpulsation improves symptoms and exercise tolerance in patients with symptomatic coronary artery disease (CAD). However, the exact mechanisms by which this technique exerts its clinical(More)
Arousals from sleep are associated with increased sympathetic activation and are therefore associated with peripheral vasoconstriction. We hypothesized that digital vasoconstrictions as measured by peripheral arterial tonometery (PAT), combined with an increase in pulse rate, would accurately reflect arousals from sleep, and can provide an autonomic arousal(More)
OBJECTIVES AND BACKGROUND Arousals from sleep are associated with increased sympathetic activation and therefore with peripheral vasoconstriction. Sleep fragmentation in the form of multiple arousals is associated with daytime somnolence and cognitive impairment; however, manual scoring of arousal is time consuming and problematic due to relatively high(More)
To the editor—Rapid-eye-movement (REM) sleep is associated with more sympathetic activation than is NONREM sleep. So far, there are no data regarding vascular tone during REM and NONREM sleep in humans. Using a new plethysmographic technique to measure peripheral arterial tone (PAT), we report here that REM sleep in humans is associated with considerable(More)
We report a novel approach to the determination of sleep apnea based on measuring the peripheral circulatory responses in a primary condition of disordered breathing. The apparatus is a finger plethysmograph coupled to a constant volume, variable pressure, pneumatic system. The plethysmograph's tip (measurement site) is composed of two parallel opposing(More)
The male predominance in obstructive sleep apnea (OSA) is currently poorly understood although differences in pharyngeal airway anatomy and physiology have been proposed. As the response to inspiratory resistive loading (IRL) provides important information on both airway collapsibility (mechanics) and ventilatory control, we compared this respiratory(More)
There is current controversy as to whether electrical stimulation of upper airway musculature can be used us a beneficial treatment modality in patients with obstructive sleep apnoea syndrome. Increased upper airway (UAW) muscle activity decreases UAW resistance (Ruaw) in isolated UAW of dogs. In the present study, we evaluated the effect of UAW muscle(More)