Search results for " blood flow"
showing 10 items of 305 documents
Non invasive blood flow measurement in cerebellum detects minimal hepatic encephalopathy earlier than psychometric tests
2013
AIM: To assess whether non invasive blood flow measurement by arterial spin labeling in several brain regions detects minimal hepatic encephalopathy. METHODS: Blood flow (BF) was analyzed by arterial spin labeling (ASL) in different brain areas of 14 controls, 24 cirrhotic patients without and 16 cirrhotic patients with minimal hepatic encephalopathy (MHE). Images were collected using a 3 Tesla MR scanner (Achieva 3T-TX, Philips, Netherlands). Pulsed ASL was performed. Patients showing MHE were detected using the battery Psychometric Hepatic Encephalopathy Score (PHES) consisting of five tests. Different cognitive and motor functions were also assessed: alterations in selective attention we…
Influence of PEEP on cerebral blood flow and cerebrovascular autoregulation in patients with acute respiratory distress syndrome.
2013
High levels of positive end-expiratory pressure (PEEP), as part of the treatment in patients with acute respiratory distress syndrome (ARDS), may prevent alveolar collapse and maintain oxygenation. PEEP potentially reduces cerebral venous return, increases intracranial blood volume, and may, therefore, affect cerebral blood flow (CBF) and cerebrovascular autoregulation (AR). This study investigates the effect of PEEP on CBF and AR in patients with respiratory failure.CBF velocity was measured using transcranial doppler and correlated with the invasive arterial blood pressure curve to calculate the index of AR Mx (Mx0.3 indicates impaired AR). Mx was measured at lower PEEP levels and after i…
Quantification of fluorescent dyes in organ tissue samples via HPLC analysis
2017
Abstract The determination of regional blood flow via the accumulation of fluorescent microspheres is a concept regularly used in medical research. Typically, the microbeads get extracted from the tissue of interest and are then quantified by measuring the absorption or fluorescence of the incorporated dyes without further separation from the medium. However, in that case the absorption spectra of different dyes can overlap when used simultaneously, leading to an overestimation of the concentration. Additionally, background absorption from the medium can be problematic. Therefore, a high performance liquid chromatography method for the simultaneous detection of four dyes (orange, crimson, y…
Changes of arterial hemodynamics in patients with type 2 diabetes mellitus or impaired glucose tolerance
2006
Aim: The aim of our study was to evaluate the arterial hemodynamics in patients with type 2 diabetes mellitus or impaired glucose tolerance without clinical or Doppler evidence of peripheral arterial disease, in order to early detect vascular damage. Methods. We studied 20 subjects (12 men and 8 women, aged between 48 and 62 years) with type 2 diabetes mellitus (Group 1), 20 subjects (11 men and 9 women, aged between 49 and 61 years) with reduced glucose tolerance (Group 2), and 20 normal subjects (10 men and 10 women, aged between 48 and 62 years) (Group 3). Each subject underwent strain-gauge plethysmography and the following parameters were evaluated: rest flow (RF); peak flow (PF); PF/R…
Transpulmonary cardiac output measurement in a rat model of cardiac arrest and CPR: Impact of vascular access
2009
Objective: The present study investigated the impact of the vascular access site for cardiac output (CO) measurement by thermodilution on survival and neurohistopathological injury in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Secondary the influence of the vascular access site on cardiac output measurements was examined. Methods: Rats underwent asphyxial CA and CPR. Thermocouple probes were either placed via the femoral artery into the bifurcation of abdominal aorta/iliac artery (Femoral) or via the carotid artery into the aortic arch (Carotid). CPR was initiated after 9 min CA. Local cerebral blood flow (lCBF) and CO were assessed for 120 min after restora…
Nitric oxide modulates cerebral blood flow stimulation by acetazolamide in the rat cortex: a laser Doppler scanning study
2001
Abstract The involvement of nitric oxide (NO) in cerebral blood flow (CBF) stimulation by acetazolamide was studied in anaesthetised, mechanically ventilated Wistar rats. CBF was monitored by laser Doppler scanning. Acetazolamide induced a long-lasting significant rCBF-increase. Application of N G -Nitro- l -arginine (L-NNA), an inhibitor of all NO synthetases (NOS), prevented CBF stimulation by acetazolamide. Continuous infusion of the exogenous NO donor SIN-1 (3-morpholinosydnonimine) suppressed L-NNA induced increases of mean arterial blood pressure without effect on rCBF in comparison to baseline. Additional acetazolamide injection then again caused a significant increase of rCBF in spi…
Nifedipine improves blood flow and oxygen supply, but not steady-state oxygenation of tumours in perfusion pressure-controlled isolated limb perfusio…
2002
Isolated limb perfusion allows the direct application of therapeutic agents to a tumour-bearing extremity. The present study investigated whether the dihydropyridine-type Ca2+-channel blocker nifedipine could improve blood flow and oxygenation status of experimental tumours during isolated limb perfusion. Perfusion was performed by cannulation of the femoral artery and vein in rats bearing DS-sarcoma on the hind foot dorsum. Perfusion rate was adjusted to maintain a perfusion pressure of 100–140 mmHg throughout the experiment. Following equilibration, nifedipine was continuously infused for 30 min (8.3 μg min−1 kg−1 BW). During constant-pressure isolated limb perfusion, nifedipine can signi…
Regional perfusion and oxygenation of tumors upon methylxanthine derivative administration
1998
Abstract Purpose: The use of methylxanthine derivatives has been postulated as a means of increasing tumor perfusion and thus ameliorating tumor hypoxia. The aim of this study was to quantify and compare the effects of three methylxanthine derivatives: pentoxifylline (PX), torbafylline (TB), and HWA 138 (HW) on tumor perfusion and oxygenation. Methods and Materials: Anesthetized Sprague Dawley rats with DS-sarcomas implanted subcutaneously onto the hind foot dorsum were used in this study. Mean arterial blood pressure (MABP) was measured throughout experiments. Regional red blood cell (RBC) flux was monitored using a multichannel laser Doppler device and tumor oxygenation on a more global l…
The Hemodynamic Effects of Ephedrine on the Onset Time of Rocuronium in Pigs
2004
Several studies have found a correlation between the onset time of muscle relaxants, cardiac index, and muscle blood flow. Ephedrine increases these hemodynamic variables and shortens onset time of rocuronium in humans. Our aim in this animal study was to determine the effect of ephedrine on the onset time of rocuronium, cardiac index, and muscle blood flow after administration of thiopental. At predefined measuring points, mean arterial blood pressure and cardiac index were measured invasively and onset time was determined mechanomyographically. Twenty-four pigs were randomly assigned to three groups. Group I received etomidate and subsequently rocuronium (2 x 95% effective dose). Instead …
Local Cerebral Blood Flow in a Rat Cortical Vein Occlusion Model
1996
The symptoms following sinus and vein occlusion observed in patients and experimental animals display a considerable variability that so far remains largely unexplained. In a rat cortical vein occlusion model using a photochemical thrombotic technique, we examined changes in the cerebral venous flow pattern by fluorescence angiography and regional cerebral blood flow (rCBF) and cerebral blood volume fraction (CBVF) by a modern laser Doppler “scanning” technique. Brain damage was assessed histologically. Fluorescence angiographic findings fell into two groups: group A, rats with an altered venous flow pattern after occlusion (n = 12), and group B, rats with interruption of blood flow and/or…