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Results 201 - 250 of 1579
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Ogata Hisayoshi - - 2010
We report a case of an individual with cervical spinal cord injury who showed a unique blood pressure response during passive standing and passive walking-like leg movement, i.e., hypertension with standing and hypotension with leg movement.
Thijs Roland D - - 2010
In autonomic failure (AF), blood pressure (BP) falls upon standing which is commonly ascribed to defective vasoconstriction and excessive pooling. Observations on the amount of pooling in AF are contradictory. We evaluated pooling using strain-gauge plethysmography (SGP) during head-up tilt (HUT) with a parachute harness fixed to the tilt table ...
Kai Tatsuya - - 2009
The current study was conducted to examine the effects of cilnidipine, a dual L/N-type calcium channel blocker, on blood pressure, pulse rate, and autonomic functions in patients with mild-to-moderate hypertension. Sixteen patients with mild-to-moderate hypertension (8 males and 8 females; 44-72 years of age) were treated with cilnidipine (10 mg/day) ...
Kiviniemi Antti M - - 2010
Altered frequency of slow (0.04-0.15Hz) arterial pressure and R-R interval oscillations has been observed in various diseases but the mechanisms for this frequency shift are unclear. The median (Med) frequencies of slow R-R interval and blood pressure (BP) oscillations were recorded in 11 healthy subjects with paced breathing (0.25Hz) during ...
Ziemssen Tjalf - - 2010
Symptoms of cardiovascular dysautonomia are a common occurrence in Parkinson's disease (PD). In addition to this dysautonomia as part of PD itself, dysfunction of the autonomic nervous system (ANS) can be triggered as a side-effect of drug treatment interacting with the ANS or - if prominent and early - an ...
Notarius Catherine F - - 2009
Many heart failure (HF) patients exhibit paradoxical forearm vasodilation when central blood volume is reduced by lower body negative pressure (LBNP). We tested the hypothesis that this response results from reflex sympathetic withdrawal. We recorded simultaneously forearm blood flow, muscle sympathetic nerve activity (MSNA), and plasma norepinephrine (PNE) during four ...
Cooke William H - - 2009
Activation of sympathetic efferent traffic is essential to maintaining adequate arterial pressures during reductions of central blood volume. Sympathetic baroreflex gain may be reduced, and muscle sympathetic firing characteristics altered with head-up tilt just before presyncope in humans. Volume redistributions with lower body negative pressure (LBNP) are similar to those ...
Fan Xiao-han - - 2009
AIM: The genetic background of orthostatic blood pressure dysregulation remains poorly understood. Since the renin-angiotensin system plays an important role in blood pressure regulation and response to position change, we hypothesized that angiotensin-converting enzyme (ACE) and ACE2 genetic polymorphisms might contribute, at least partially, to orthostatic blood pressure dysregulation in ...
Ogata Hisayoshi - - 2009
OBJECTIVE: To determine whether arterial hypotension is related to hyperventilation during standing in individuals with complete spinal cord injury (SCI). METHODS: Sixteen individuals with SCI (thoracic 1 to thoracic level 12, ASIA grade: A) and 18 able-bodied individuals participated in this study. Individuals with SCI were divided into a group ...
Hindes Mariah - - 2009
The purpose of this study was to investigate the functional relationship between subsyndromal orthostatic blood pressure regulation and motor skills in 3-5 year old children. It is known that the efficiency of orthostatic blood pressure regulation is affected by a variety of processes, most especially neurohumoral as well as sympathetic ...
Newman David G - - 2009
INTRODUCTION: Fighter pilots report G tolerance increases with regular exposure. Our previous work has shown that the cardiovascular system of +Gz-adapted fighter pilots responds differently to orthostatic challenges than that of non-pilots. A +Gz training effect in pilots after repetitive +Gz exposure has also been shown. Individual pilot factors such ...
Zaar M - - 2009
We considered that a moderate reduction of the central blood volume (CBV) may activate the coagulation system. Lower body negative pressure (LBNP) is a non-invasive means of reducing CBV and, thereby, simulates haemorrhage. We tested the hypothesis that coagulation markers would increase following moderate hypovolemia by exposing 10 healthy male ...
Hughson Richard L - - 2009
The cardiovascular system undergoes major changes in stress with space flight primarily related to the elimination of the head-to-foot gravitational force. A major observation has been that the central venous pressure is not elevated early in space flight yet stroke volume is increased at least early in flight. Recent observations ...
Immink Rogier V - - 2009
In the upright position, cerebral blood flow is reduced, maybe because arterial carbon dioxide partial pressure (Pa(CO(2))) decreases. We evaluated the time-dependent influence of a reduction in Pa(CO(2)), as indicated by the end-tidal Pco(2) tension (Pet(CO(2))), on cerebral perfusion during head-up tilt. Mean arterial pressure, cardiac output, middle cerebral artery ...
Sharma Pramod - - 2009
BACKGROUND: Heart rate variability is actually a misnomer for R to R variability in cardiac cycle. Variation in successive cycle length is called the heart rate variability (HRV). Head-up tilt is a model of studying cardiovascular haemodynamics, which reflects in heart rate variability (HRV). OBJECTIVES: To study the effect of ...
Tahvanainen Anna - - 2009
AIMS: To examine the effects of salbutamol and L-arginine, two compounds acting largely on the endothelium, and the endothelium-independent agent nitroglycerin on blood pressure, arterial compliance, cardiac function and vascular resistance. METHODS: Continuous radial pulse wave analysis, whole-body impedance cardiography, and plethysmographic blood pressure from fingers in the supine position ...
Goswami Nandu - - 2009
We studied individual stability of orthostatic tolerance as well as presyncopal signs and symptoms across four runs in subjects undergoing combined head-up tilt (HUT) and lower body negative pressure (LBNP). Ten healthy young males were subjected to HUT+ LBNP, to achieve a presyncopal end-point. Four test runs were separated by ...
Yi Chung-Hwi - - 2009
The damage caused by pressure in bedridden hospitalized patients is attributable to the body tissues becoming compressed against bony prominences, which results in poor capillary perfusion. Automated inclining beds were developed in this study to assist patients in repositioning, with the aim of quantifying the effects of 3 types of ...
Koyama Yu - - 2009
To assess heart rate (HR) regulation in Machado-Joseph disease (MJD), we evaluated HR variability at rest and the initial HR response to standing suddenly in 13 MJD patients and 26 normal control subjects. A head-up tilt (HUT) test involving the monitoring of blood pressure, HR, and cerebral oxy/deoxyhemoglobin concentration was ...
Wilson T E - - 2009
The Frank-Starling 'law of the heart' is implicated in certain types of orthostatic intolerance in humans. Environmental conditions have the capacity to modulate orthostatic tolerance, where heat stress decreases and cooling increases orthostatic tolerance. The objective of this project was to test the hypothesis that heat stress augments and cooling ...
Fedorowski Artur - - 2009
OBJECTIVES: Prevalence and determinants of orthostatic hypotension remain largely unexplored in younger individuals without significant burden of chronic diseases. METHODS: We investigated frequency and main associations of impaired orthostatic response in a cohort of 469 middle-aged hypertensive patients and 453 of their normotensive first-degree relatives. RESULTS: 13.4% of hypertensive and ...
Carter Jason R - - 2009
Sympathetic baroreflex sensitivity (BRS) and muscle sympathetic nerve activity (MSNA) responses during early follicular (EF) and midluteal (ML) phases of the menstrual cycle are controversial. We hypothesize an augmented sympathetic BRS and MSNA response to orthostatic stress during the ML phase of the menstrual cycle. MSNA, mean arterial pressure (MAP), ...
Goswami Nandu - - 2009
AIMS: Combined head up tilt (HUT) and lower body negative pressure (LBNP) can be used to exploit the full spectrum of cardiovascular control mechanisms and to reveal characteristics of individual blood pressure control. We studied whether the response to combined HUT and LBNP was reproducible within subjects and whether characteristic ...
Meyer Christian - - 2010
During the development of neurocardiogenic syncope (NCS) postural dependant venous blood pooling sets off a cascade of autonomic reflexes. This causes an initial rise in sympathetic tone, which is followed by an overshoot parasympathetic activation resulting in systemic vasodilatation and/or sinus bradycardia. However, other factors like associated hyperventilation or changes ...
Keller David M - - 2009
Whole-body heat stress reduces orthostatic tolerance via a yet to be identified mechanism(s). The reduction in central blood volume that accompanies heat stress may contribute to this phenomenon. The purpose of this study was to test the hypothesis that acute volume expansion prior to the application of an orthostatic challenge ...
Aletti Federico - - 2009
In this paper, the effects of bed rest-induced cardiovascular deconditioning were investigated by means of a previously developed multivariate model for the assessment of arterial control of circulation. The vascular response to exercise and tilt, before and after a 14-day head down tilt bed rest, was identified and disentangled from ...
Bezemer Rick - - 2009
INTRODUCTION: Hypovolemia and hypovolemic shock are life-threatening conditions that occur in numerous clinical scenarios. Near-infrared spectroscopy (NIRS) has been widely explored, successfully and unsuccessfully, in an attempt to use it as an early detector of hypovolemia by measuring tissue oxygen saturation (StO2). In order to investigate the measurement site dependence ...
MacDonald Blair - - 2009
To test the hypothesis that, in comparison with a heavier, larger and more expensive manual tilt-in-space wheelchair, a lightweight manual wheelchair equipped with new rear antitip devices provides comparable mean sitting pressures in the tilted position, each of eight able-bodied participants sat for 8 mins in each wheelchair, upright, and ...
Carew Sheila - - 2009
A 21-year-old female reports an 18-month history of light-headedness on standing. This is often associated with palpitations and a feeling of intense anxiety. She has had two black-outs in the past 12 months. She is not taking any regular medications. Her supine blood pressure was 126/84 mmHg with a heart ...
Kostopoulou Anna - - 2009
Neurocardiogenic syncope is one of the most common types of syncope, characterized by arterial vasodilatation with or without bradycardia. The regulation of blood pressure and heart rate is the result of a complex reaction between the central and peripheral nervous system with the circulatory system. Multiple therapies, pharmaceutical and interventional, ...
Tessendorf Bernd - - 2009
In recent years, the monitoring of sitting postures was discovered to be a promising measure of healthy sitting behavior, comfort, physical wellness and emotions. Most state-of-the-art systems for monitoring sitting behavior are based on supervised methods that are limited to a fixed set of classes. We present a method that ...
Madden Kenneth M - - 2009
Neurocardiogenic syncope (formerly vasovagal) accounts for large numbers of falls in older adults and the mechanisms are poorly understood. This study examined the differences in baseline arterial baroreflex function in older adults with and without a neruocardiovascular response to orthostatic stress. Subjects were divided into two groups based on the ...
Fu Qi - - 2009
Low levels (i.e., </=20 mmHg) of lower body negative pressure (LBNP) have been utilized to unload "selectively" cardiopulmonary baroreceptors in humans, since steady-state mean arterial pressure and heart rate (HR) have been found unchanged at such levels. However, transient reductions in blood pressure (BP), followed by reflex compensation, may occur ...
Pramanik T - - 2008
Postural syncope may be noticed in otherwise normal persons with defective postural reflexes. Vasoconstrictor reserve--the extent to which total peripheral resistance can be increased from baseline condition is an important determinant of orthostatic tolerance. Women showed low autonomic support of blood pressure. The case of neurally mediated syncope is known ...
Brown S J - - 2008
Cardiac vagal withdrawal when moving from supine to an upright posture may be independent of respiratory sinus arrhythmia. Further, ventilatory efficiency of an upright lung may improve with clustering of heart beats during inhalation. We studied healthy human subjects (n=8, 6 male) during supine rest (SUP) and 80 degrees head-up ...
Harkema Susan J - - 2008
Prospective assessment of cardiovascular control in individuals with spinal cord injury (SCI) in response to active stand training. Cardiovascular parameters were measured at rest and in response to orthostatic challenge before and after training in individuals with clinically complete SCI. The goal of this study was to evaluate the effect ...
Privett S E - - 2010
To investigate the regulation of blood pressure in response to an orthostatic challenge in athletes running a marathon. 10 experienced male runners (mean (SD) age 29 (4) years) were tested on the day prior to the 2004 London Marathon, and again immediately postrace (race time 210 (36) min). In addition, ...
Gemignani Tiago - - 2008
Atherosclerosis of peripheral arteries typically affects vessels of the lower limbs, suggesting that local hemodynamic stimuli play a role in this process. Our study evaluated the effects of body postural changes on carotid and popliteal blood pressure, circumferential wall tension (CWT) and arterial strain, and investigated the relationship between such ...
Peterson M - - 2008
OBJECTIVE: Intensive care unit patients are at particular risk for pressure ulcers and ventilator-associated pneumonia. Current guidelines recommend that mechanically ventilated patients be kept in a semirecumbent position with the head of bed elevated 30 degrees -45 degrees to prevent aspiration and ventilator-associated pneumonia. We tested the effects of elevating ...
Lee Jangwoen - - 2008
We demonstrate noninvasive near-infrared diffuse optical spectroscopy (DOS) measurements of tissue hemoglobin contents that can track progressive reductions in central blood volume in human volunteers. Measurements of mean arterial blood pressure (MAP), heart rate (HR), stroke volume (SV), and cardiac output (Q) are obtained in ten healthy human subjects during ...
Fan C W - - 2008
BACKGROUND: Sleeping with the head of bed tilted upwards (SHU) is recommended as a treatment of orthostatic hypotension though the supporting evidence is weak. AIM: To investigate the physiological effects of SHU amongst a group of young healthy volunteers. METHODS: Twenty-nine volunteers, mean age 22 years, underwent 1-week of SHU ...
Wong Brett J - - 2008
The "push-pull" effect denotes the reduced tolerance to +G(z) (hypergravity) when +G(z) stress is preceded by exposure to hypogravity, i.e., fractional, zero, or negative G(z). The purpose of this study was to test the hypothesis that an exaggerated, myogenically mediated rise in leg vascular conductance contributes to the push-pull effect, ...
Chi Lorne - - 2008
Orthostatic hypotension is a common condition for individuals with stroke or spinal cord injury. The inability to regulate the central nervous system will result in pooling of blood in the lower extremities leading to orthostatic intolerance. This study compared the use of functional electrical stimulation (FES) and passive leg movements ...
Vara-González Luis - - 2008
OBJECTIVE: To describe the postural changes in blood pressure and correlates among the general population of Cantabria, a region in the north of Spain. METHODS: Between 2002 and 2004 blood pressure measurements were taken in a seated position and after 1 and 3 min standing on a random sample of ...
Vogel Elizabeth R - - 2008
Blood pressure changes in response to the Valsalva maneuver (VM), which reflect the integrity of the baroreflex that regulates blood pressure. Performing this maneuver in the standard supine position often prevents adequate venous preload reduction, resulting in a rise rather than a fall in blood pressure, the "flat-top" Valsalva response. ...
Hoad A - - 2008
BACKGROUND: It has been suggested that postural orthostatic tachycardia syndrome (POTS) be considered in the differential diagnosis of those with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). Currently, measurement of haemodynamic response to standing is not recommended in the UK NICE CFS/ME guidelines. OBJECTIVES: To determine prevalence of POTS in patients with ...
Stolz Erwin - - 2009
BACKGROUND: Although there exists a large body of knowledge on the regulation of arterial cerebral hemodynamics, little is known about the cerebral venous outflow (CVO). METHODS: In 19 healthy volunteers, the middle cerebral artery and the straight sinus were examined using transcranial Doppler sonography. Arterial and venous mean flow velocities ...
Ramirez-Marrero Farah A - - 2008
Orthostatic stress such as head-up tilt (HUT) elicits a wide range of heart rate (HR) and arterial pressure (AP) responses among healthy individuals. In this study, we evaluated cardiovascular dynamics in healthy subjects with different HR responses to HUT, but without autonomic dysfunction. We measured AP (brachial artery) and HR ...
Iacoviello Massimo - - 2008
AIMS: The aim of this study was to evaluate arterial baroreflex control of heart rate immediately before head-up tilt test (HUT)-induced vasovagal syncope (VVS). METHODS AND RESULTS: We enrolled 97 otherwise healthy subjects with recurrent unexplained syncope. After 10 min of rest in supine position, they underwent a passive HUT ...
Krabbendam Ineke - - 2008
Head-up tilt (HUT) induces a reduction in preload, which is thought to be restored through sympathetic venoconstriction, reducing unstressed volume (V(u)) and venous compliance (VeC). In this study, we assessed venous inflow and outflow responses and their reproducibility and determined the relation with autonomic function during HUT. Eight healthy non-pregnant ...
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