نتایج جستجو برای: impedance plethysmography
تعداد نتایج: 38515 فیلتر نتایج به سال:
BACKGROUND Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. METHOD The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity w...
INTRODUCTION Exposure to microgravity is associated with increased leg venous compliance and reductions in cardiac output, baroreflex functions, and tolerance to orthostatism. However, the effects of chronic exposure to high-G environments are unknown. In addition, there is evidence that females have lower orthostatic tolerance than males, although the underlying mechanisms are unclear. Therefo...
Stokes (1) reported that the colored substance in blood carries oxygen. This was followed by Hoppe-Seyler (2), who first crystallized this substance and coined the term hemoglobin. Additionally, it was shown that the pattern of light absorption changes when shaken with air (2). Hertzman (3) described using photoelectric plethysmography of fingers and toes as a dynamic analysis of the peripheral...
BACKGROUND Finger plethysmography and thermometry are objective measures used to assess the vascular aspect of hand-arm vibration syndrome (HAVS). Research to date shows poor correlation between these tests and Stockholm Workshop Scale (SWS) vascular stage. Clinicians, researchers and compensation boards require objective means to diagnose and quantify HAVS. AIMS To define the specificity and...
Electrical impedance myography (EIM) is a non-invasive technique for the evaluation of neuromuscular disease that relies upon the application and measurement of high-frequency, low-intensity electrical current. EIM assesses disease-induced changes to the normal composition and architecture of muscle, including myocyte atrophy and loss, edema, reinnervation, and deposition of endomysial connecti...
BACKGROUND The Fontan circulation is critically dependent on elevated venous pressures to sustain effective venous return. We hypothesized that chronically increased systemic venous pressures lead to adaptive changes in regional and peripheral vessels to maintain cardiac output, especially when patients are upright. METHODS AND RESULTS Nine post-Fontan procedure patients (aged 13 to 24 years)...
Our prior studies indicated that postural fainting relates to splanchnic hypervolemia and thoracic hypovolemia during orthostasis. We hypothesized that thoracic hypovolemia causes excessive sympathetic activation, increased respiratory tidal volume, and fainting involving the pulmonary stretch reflex. We studied 18 patients 13-21 yr old, 11 who fainted within 10 min of upright tilt (fainters) a...
Variants of postural tachycardia syndrome (POTS) are associated with increased ["high-flow" POTS (HFP)], decreased ["low-flow" POTS (LFP)], and normal ["normal-flow" POTS (NFP)] blood flow measured in the lower extremities while subjects were in the supine position. We propose that postural tachycardia is related to thoracic hypovolemia during orthostasis but that the patterns of peripheral blo...
Increased blood pressure (BP) and heart rate during exercise characterizes the exercise pressor reflex. When evoked by static handgrip, mechanoreceptors and metaboreceptors produce regional changes in blood volume and blood flow, which are incompletely characterized in humans. We studied 16 healthy subjects aged 20-27 yr using segmental impedance plethysmography validated against dye dilution a...
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