Venous Circulation

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Carl P Herbort - One of the best experts on this subject based on the ideXlab platform.

  • Prolonged retinal arterio-Venous Circulation time by fluorescein but not by indocyanine green angiography in birdshot chorioretinopathy
    Ocular Immunology and Inflammation, 1997
    Co-Authors: Yan Guex-crosier, Carl P Herbort
    Abstract:

    Purpose: To compare retinal arterio-Venous Circulation time by fluorescein (FA) and indocyanine green angiography (ICGA) in birdshot chorioretinopathy. Methods: We analyzed prolonged retinal arterio-Venous fluorescein transit time, a known feature in birdshot chorioretinopathy and correlated it with ICGA findings in four consecutive patients. Results: Mean retinal arterio-Venous fluorescein Circulation time was 31.1 ± 5.2 seconds, a transit time significantly longer than in a group of ten patients with sarcoid-osis (9.45 ± 3.36 sec., p

  • prolonged retinal arterio Venous Circulation time by fluorescein but not by indocyanine green angiography in birdshot chorioretinopathy
    Ocular Immunology and Inflammation, 1997
    Co-Authors: Yan Guexcrosier, Carl P Herbort
    Abstract:

    Purpose: To compare retinal arterio-Venous Circulation time by fluorescein (FA) and indocyanine green angiography (ICGA) in birdshot chorioretinopathy. Methods: We analyzed prolonged retinal arterio-Venous fluorescein transit time, a known feature in birdshot chorioretinopathy and correlated it with ICGA findings in four consecutive patients. Results: Mean retinal arterio-Venous fluorescein Circulation time was 31.1 ± 5.2 seconds, a transit time significantly longer than in a group of ten patients with sarcoid-osis (9.45 ± 3.36 sec., p<0.0001) and in a group of three cases with Vogt-Koyanagi-Harada disease (7.0 ± 1,i sec., p<0.0001). Conclusion: Prolonged fluorescein arterio-Venous transit time seems to be a characteristic feature of birdshot chorioretinopathy that does however not reflect the actual intravas-cular hemodynamic situation but diffuse blood-retinal barrier damage allow-ing exudation, slow gradual tissue impregnation and delayed Venous reab-sorption of small molecules like fluorescein.

Elisabet U.m. Blix - One of the best experts on this subject based on the ideXlab platform.

  • direct connections between the spinal epidural space and the Venous Circulation in humans
    Regional Anesthesia and Pain Medicine, 2011
    Co-Authors: Charles W. Buffington, Larry Nichols, Pauline L Moran, Elisabet U.m. Blix
    Abstract:

    Background and Objectives: Our previous studies in pigs indicate that direct connections exist between the spinal epidural space and the Venous Circulation. We wondered if similar connections occur in humans and have extended our investigations to human cadavers awaiting autopsy. Methods: We studied 10 recently dead human bodies. We inserted 2 Tuohy needles into the epidural space of the lower thoracic spine at adjacent interspaces. We infused saline with a constant-flow pump into 1 needle and measured the resulting pressure through the other. Epidural pressure increased to a steady plateau during fluid infusion, and this value was recorded at several flow rates. The pressure decay after flow stopped was also recorded. Then we infused radiopaque contrast, removed the needles, and obtained a computed tomographic scan of the spine from the foramen magnum to the coccyx. Results: Pressure in the epidural space increased to a plateau during saline infusion. Higher flow rates produced higher plateau pressures. Plots of plateau pressure versus infusion rate were linear in all bodies. The slope of the flow-pressure plot gave a steady-state resistance (543 ± 638 mm Hg·s/mL). The time constant of the pressure decay curve allowed calculation of initial capacitance (0.090 ± 0.062 mL/mm Hg). Contrast could be identified in veins around the spinal column in all bodies. Contrast was found most commonly in the deep veins of the neck (7 bodies) and in veins originating in the area of the brachial plexus (7 bodies). Contrast was found less commonly and in smaller amounts in veins draining into the azygous system (5 bodies) and the lumbar veins (5 bodies). No contrast was found in veins in the sacral area. Conclusions: A direct connection between the spinal epidural space and the Venous Circulation has been demonstrated in human cadavers. The connection is most commonly found in the cervical and upper thoracic spine.

  • A macromolecular tracer indicates that the spinal epidural space connects directly to the Venous Circulation in pigs.
    Regional Anesthesia and Pain Medicine, 2010
    Co-Authors: Charles W. Buffington, Elisabet U.m. Blix
    Abstract:

    Background and Objectives: Air injected into the epidural space of the spine reaches the heart within 15 secs, suggesting easy access to the bloodstream. We wished to quantify the washout of a macromolecular tracer (albumin labeled with Evans blue) from the thoracic epidural space. Methods: Eleven juvenile pigs were anesthetized with isoflurane and positioned on their sides. We injected a bolus of the tracer into the thoracic epidural space followed by serial saline infusions (total, 50-70 mL). We measured plasma concentrations of the tracer during washout. Finally, we injected Microfil (a liquid rubber compound that hardens on standing) into the epidural space and later inspected with a dissecting microscope the nerve roots and veins draining the spine. Results: More than half (60% ± 12%; range, 31%-79%) of the tracer injected in the epidural space was detected in the bloodstream. Microfil was detected in the veins draining the cervical or high thoracic spine, but never in veins draining the lumbar spine or sacrum. Conclusions: Because the macromolecular tracer cannot enter the bloodstream by absorption, these results indicate that pathways capable of handling bulk flow connect the spinal epidural space to the Venous Circulation. These pathways are located in the cervical and high thoracic spine of the pig.

Charles W. Buffington - One of the best experts on this subject based on the ideXlab platform.

  • direct connections between the spinal epidural space and the Venous Circulation in humans
    Regional Anesthesia and Pain Medicine, 2011
    Co-Authors: Charles W. Buffington, Larry Nichols, Pauline L Moran, Elisabet U.m. Blix
    Abstract:

    Background and Objectives: Our previous studies in pigs indicate that direct connections exist between the spinal epidural space and the Venous Circulation. We wondered if similar connections occur in humans and have extended our investigations to human cadavers awaiting autopsy. Methods: We studied 10 recently dead human bodies. We inserted 2 Tuohy needles into the epidural space of the lower thoracic spine at adjacent interspaces. We infused saline with a constant-flow pump into 1 needle and measured the resulting pressure through the other. Epidural pressure increased to a steady plateau during fluid infusion, and this value was recorded at several flow rates. The pressure decay after flow stopped was also recorded. Then we infused radiopaque contrast, removed the needles, and obtained a computed tomographic scan of the spine from the foramen magnum to the coccyx. Results: Pressure in the epidural space increased to a plateau during saline infusion. Higher flow rates produced higher plateau pressures. Plots of plateau pressure versus infusion rate were linear in all bodies. The slope of the flow-pressure plot gave a steady-state resistance (543 ± 638 mm Hg·s/mL). The time constant of the pressure decay curve allowed calculation of initial capacitance (0.090 ± 0.062 mL/mm Hg). Contrast could be identified in veins around the spinal column in all bodies. Contrast was found most commonly in the deep veins of the neck (7 bodies) and in veins originating in the area of the brachial plexus (7 bodies). Contrast was found less commonly and in smaller amounts in veins draining into the azygous system (5 bodies) and the lumbar veins (5 bodies). No contrast was found in veins in the sacral area. Conclusions: A direct connection between the spinal epidural space and the Venous Circulation has been demonstrated in human cadavers. The connection is most commonly found in the cervical and upper thoracic spine.

  • A macromolecular tracer indicates that the spinal epidural space connects directly to the Venous Circulation in pigs.
    Regional Anesthesia and Pain Medicine, 2010
    Co-Authors: Charles W. Buffington, Elisabet U.m. Blix
    Abstract:

    Background and Objectives: Air injected into the epidural space of the spine reaches the heart within 15 secs, suggesting easy access to the bloodstream. We wished to quantify the washout of a macromolecular tracer (albumin labeled with Evans blue) from the thoracic epidural space. Methods: Eleven juvenile pigs were anesthetized with isoflurane and positioned on their sides. We injected a bolus of the tracer into the thoracic epidural space followed by serial saline infusions (total, 50-70 mL). We measured plasma concentrations of the tracer during washout. Finally, we injected Microfil (a liquid rubber compound that hardens on standing) into the epidural space and later inspected with a dissecting microscope the nerve roots and veins draining the spine. Results: More than half (60% ± 12%; range, 31%-79%) of the tracer injected in the epidural space was detected in the bloodstream. Microfil was detected in the veins draining the cervical or high thoracic spine, but never in veins draining the lumbar spine or sacrum. Conclusions: Because the macromolecular tracer cannot enter the bloodstream by absorption, these results indicate that pathways capable of handling bulk flow connect the spinal epidural space to the Venous Circulation. These pathways are located in the cervical and high thoracic spine of the pig.

Takayuki Sahata - One of the best experts on this subject based on the ideXlab platform.

  • Effects of endothelin-induced nitric oxide on Venous Circulation and renal water-electrolyte handling.
    Journal of Cardiovascular Pharmacology, 1998
    Co-Authors: Kozo Ota, Tokihisa Kimura, Masaru Shoji, Masahiro Ota, Takeharu Funyu, Takefumi Mori, Takayuki Sahata
    Abstract:

    To assess the interaction of endothelin (ET) with nitric oxide (NO) and the effects on Venous Circulation and handling of renal water and electrolytes, ET (1.0 ng/kg/min) or saline was administered with or without three doses (0.27, 2.7 and 27 ng/kg/min for 40 min) of N ω -nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor, in anesthetized dogs. ET increased total peripheral resistance (TPR), pulmonary capillary wedge pressure (PCWP), urine flow (UF), and urinary K excretion (UKV), and decreased cardiac output (CO), urinary osmolality (Uosm), renal plasma flow (RPF), and glomerular filtration rate (GFR). L-NAME increased blood pressure (BP). TPR, PCWP, right atrial pressure (RAP), and mean circulatory filling pressure (MCFP). and decreased CO, RPF, and GFR. ET plus L-NAME markedly increased TPR, resistance to Venous return, and plasma atrial natriuretic peptide (ANP), but not BP and MCFP, and curtailed the ET-induced responses in UF, UKV, and Uosm. Plasma aldosterone (ALD) was decreased in all groups, but plasma vasopressin (AVP) and renin activity (PRA) were not altered in any group. These results indicate that ET-induced NO formation might mitigate increases in Venous as well as arterial vascular resistance and changes in renal handling of water and electrolytes, and might also play an inhibitory role in ANP release but not in PRA or AVP and ALD release.

  • Effects of endothelin-induced nitric oxide on Venous Circulation and renal water-electrolyte handling.
    Journal of cardiovascular pharmacology, 1998
    Co-Authors: Kozo Ota, Tokihisa Kimura, Masaru Shoji, Masahiro Ota, Takeharu Funyu, Takefumi Mori, Takayuki Sahata
    Abstract:

    To assess the interaction of endothelin (ET) with nitric oxide (NO) and the effects on Venous Circulation and handling of renal water and electrolytes, ET (1.0 ng/kg/min) or saline was administered with or without three doses (0.27, 2.7 and 27 ng/kg/min for 40 min) of N omega-nitro-L-arginine methyl ester (L-NAME), and NO synthase inhibitor, in anesthetized dogs. ET increased total peripheral resistance (TPR), pulmonary capillary wedge pressure (PCWP), urine flow (UF), and urinary K excretion (UKV), and decreased cardiac output (CO), urinary osmolality (Uosm), renal plasma flow (RPF), and glomerular filtration rate (GFR). L-NAME increased blood pressure (BP), TPR, PCWP, right atrial pressure (RAP), and mean circulatory filling pressure (MCFP), and decreased CO, RPF, and GFR, ET plus L-NAME markedly increased TPR, resistance to Venous return, and plasma atrial natriuretic peptide (ANP), but not BP and MCFP, and curtailed the ET-induced responses in UF, UKV, and Uosm. Plasma aldosterone (ALD) was decreased in all groups, but plasma vasopressin (AVP) and renin activity (PRA) were not altered in any group. These results indicate that ET-induced NO formation might mitigate increases in Venous as well as arterial vascular resistance and changes in renal handling of water and electrolytes, and might also play an inhibitory role in ANP release but not in PRA or AVP and ALD release.

Yan Guex-crosier - One of the best experts on this subject based on the ideXlab platform.

Related terms

  • retinal arterio venous circulation
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