Search results for "blood pressure"
showing 10 items of 1254 documents
Beta-adrenergic stimulation enhances left ventricular diastolic performance in normal subjects.
1997
To determine the effects of beta-adrenergic stimulation on transmitral Doppler echocardiography flow characteristics of left ventricular diastolic filling, we studied 10 healthy volunteers aged 23-31 years (mean age, 26.6 years) during intravenous infusion of isoprenaline in consecutive steps of 0.1, 0.2, 0.4, 0.75, and 1.5 micrograms/min (each for 15 min). Saline control infusion was given in the same manner in a crossover and blinded protocol. Compared with the infusion of placebo, stepwise increasing doses of isoprenaline caused a dose-related increase in early and late diastolic filling velocities and velocity-time integrals, a lengthening of the acceleration time, and a shortening of t…
Mechanisms of causal interaction between short-term RR interval and systolic arterial pressure oscillations during orthostatic challenge
2013
The transition from the supine to the upright position requires a reorganization of the mechanisms of cardiovascular control that, if not properly accomplished, may lead to neurally mediated syncope. We investigated how the patterns of causality between systolic arterial pressure (SAP) and cardiac RR interval were modified by prolonged head-up tilt using a novel nonlinear approach based on corrected conditional entropy (CCE) compared with the standard approach exploiting the cross-correlation function (CCF). Measures of coupling strength and delay of the causal interactions from SAP to RR and from RR to SAP were obtained in 10 patients with recurrent, neurally mediated syncope (RNMS) and 10…
Night-Time Shift Work and Related Stress Responses: A Study on Security Guards
2020
Work-related stress can induce a break in homeostasis by placing demands on the body that are met by the activation of two different systems, the hypothalamic&ndash
Blood pressure changes after automatic and fixed CPAP in obstructive sleep apnea. Relationship with nocturnal sympathetic activity.
2011
Treatment of obstructive sleep apnea (OSA) by continuous positive airway pressure (CPAP) usually causes a reduction in blood pressure (BP), but several factors may interfere with its effects. In addition, although a high sympathetic activity is considered a major contributor to increased BP in OSA, a relationship between changes in BP and in sympathetic nervous system activity after OSA treatment is uncertain. This study was undertaken to assess if, in OSA subjects under no pharmacologic treatment, treatment by CPAP applied at variable levels by an automatic device (APAP) may be followed by a BP reduction, and if that treatment is associated with parallel changes in BP and catecholamine exc…
Interaction of atenolol with furosemide and calcium and aluminum salts
1981
Six healthy subjects were treated with 100 mg atenolol. After a therapy-free interval of 4 wk the same subjects received the same dose of atenolol with furosemide, 40 mg, with calcium (as the lactate gluconate and carbonate), 500 mg, or with aluminum hydroxide, 5.6 gm. Atenolol alone and in combination was administered first as a single oral dose; a long-term 6-day treatment began 48 hr later. Addition of furosemide did not influence atenolol kinetics, but aluminum hydroxide led to an insignificant reduction (P greater than 0.05) of mean peak plasma levels of about 20% and of the area under the plasma concentration-time curve (AUC -infinity) from 5818 to 4353 ng ml-1 hr (P greater than 0.05…
Antiplatelet effects of intravenous iloprost in patients with peripheral arterial obliterative disease
1986
The dose-dependent inhibition of platelet aggregation by the chemically stable, prostacyclin-mimetic, iloprost, was studied in patients suffering from stage II-III peripheral arterial obliterative disease (PAOD). The study was designed as a randomized placebo-controlled cross-over trial. Iloprost was administered i.v. to six patients at doses of 0.5, 1.0, 2.0 or 3.0 ng/kg X min for 4 h, with an interval of 2-3 days between the infusions. During iloprost infusion, systolic and diastolic arterial blood pressure, heart rate and blood flow in the affected limb remained unchanged. In contrast, there was a considerable, dose-dependent inhibition of ADP- and thrombin-induced platelet aggregation a…
Statement of severe trauma management in France; teachings of the FIRST study
2013
Abstract Introduction The blunt trauma victim management is still a matter of debate and comparing studies involving different emergency medical services and health care organization remains fictitious. Hence, the French Intensive care Recorded in Severe Trauma (FIRST) was conducted in order to describe the severe blunt trauma management in France. The present paper aimed at recalling the main results of FIRST study. Methods The FIRST study was based on a multicenter prospective cohort of patients aged 18 or over with severe exclusive blunt trauma requiring admission to university hospital care unit within the first 72 h and/or managed by medical-Staffed Emergency Mobile Unit (SMUR). Multip…
Serial Measurement of Static and Dynamic Cerebrovascular Autoregulation After Brain Injury
2011
In patients with neuronal injury, the knowledge of the status of cerebrovascular autoregulation can help to optimize the management of the cerebral perfusion pressure. This study characterizes dynamic and static cerebrovascular autoregulation during the first 7 days after severe traumatic brain injury or intracranial hemorrhage.After approval from the IRB, 16 patients were studied. Cerebral blood flow velocity (CBFV) was measured daily for the assessment of dynamic (10 patients) and static (16 patients) cerebrovascular autoregulation in both the middle cerebral arteries using the transcranial Doppler sonography. Dynamic cerebrovascular autoregulation (dAR) was measured using the cuff-deflat…
Exploring metrics for the characterization of the cerebral autoregulation during head-up tilt and propofol general anesthesia
2022
Techniques grounded on the simultaneous utilization of Tiecks' second order differential equations and spontaneous variability of mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV), recorded from middle cerebral arteries through a transcranial Doppler device, provide a characterization of cerebral autoregulation (CA) via the autoregulation index (ARI). These methods exploit two metrics for comparing the measured MCBFV series with the version predicted by Tiecks' model: normalized mean square prediction error (NMSPE) and normalized correlation rho. The aim of this study is to assess the two metrics for ARI computation in 13 healthy subjects (age: 27 & PLUSMN; 8 yr…
Relaxin in Obstructive Sleep Apnea: Relationship with Blood Pressure and Inflammatory Mediators
2015
<b><i>Background:</i></b> Obstructive sleep apnea (OSA) is associated with nocturnal intermittent hypoxia, which may be responsible for increased circulating levels of vascular endothelial growth factor (VEGF) and inflammatory mediators, such as metalloproteinases (MMPs), and which contributes to the pathogenesis of systemic hypertension. Why some OSA patients remain normotensive is poorly understood. Relaxin-2, a pregnancy hormone, may sometimes circulate in men and could increase in hypoxic conditions. It exerts a vasodilatory activity and can modulate the release of molecules, such as MMPs and VEGF. <b><i>Objectives:</i></b> The objective o…