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Renal Perfusion (renal + perfusion)
Selected AbstractsDopamine increases renal oxygenation: a clinical study in post-cardiac surgery patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2010BENGT REDFORS Background: Imbalance of the renal medullary oxygen supply/demand relationship can cause ischaemic acute renal failure (ARF). The use of dopamine for prevention/treatment of ischaemic ARF has been questioned. It has been suggested that dopamine may increase renal oxygen consumption (RVO2) due to increased solute delivery to tubular cells, which may jeopardise renal oxygenation. Information on the effects of dopamine on renal perfusion, filtration and oxygenation in man is, however, lacking. We evaluated the effects of dopamine on renal blood flow (RBF), glomerular filtration rate (GFR), RVO2 and renal O2 demand/supply relationship, i.e. renal oxygen extraction (RO2Ex). Methods: Twelve uncomplicated, mechanically ventilated and sedated post-cardiac surgery patients with pre-operatively normal renal function were studied. Dopamine was sequentially infused at 2 and 4 ug/kg/min. Systemic haemodynamics were evaluated by a pulmonary artery catheter. Absolute RBF was measured using two independent techniques: by the renal vein thermodilution technique and by infusion clearance of paraaminohippuric acid (PAH), with a correction for renal extraction of PAH. The filtration fraction (FF) was measured by the renal extraction of 51Cr-EDTA. Results: Neither GFR, tubular sodium reabsorption nor RVO2 was affected by dopamine, which increased RBF (45,55%) with both methods, decreased renal vascular resistance (30,35%), FF (21,26%) and RO2Ex (28,34%). The RBF/CI ratio increased with dopamine. Dopamine decreased renal PAH extraction, suggestive of a flow distribution to the medulla. Conclusions: In post-cardiac surgery patients, dopamine increases the renal oxygenation by a pronounced renal pre-and post-glomerular vasodilation with no increases in GFR, tubular sodium reabsorption or renal oxygen consumption. [source] Low-dose vasopressin increases glomerular filtration rate, but impairs renal oxygenation in post-cardiac surgery patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2009G. BRAGADOTTIR Background: The beneficial effects of vasopressin on diuresis and creatinine clearance have been demonstrated when used as an additional/alternative therapy in catecholamine-dependent vasodilatory shock. A detailed analysis of the effects of vasopressin on renal perfusion, glomerular filtration, excretory function and oxygenation in man is, however, lacking. The objective of this pharmacodynamic study was to evaluate the effects of low to moderate doses of vasopressin on renal blood flow (RBF), glomerular filtration rate (GFR), renal oxygen consumption (RVO2) and renal oxygen extraction (RO2Ex) in post-cardiac surgery patients. Methods: Twelve patients were studied during sedation and mechanical ventilation after cardiac surgery. Vasopressin was sequentially infused at 1.2, 2.4 and 4.8 U/h. At each infusion rate, systemic haemodynamics were evaluated by a pulmonary artery catheter, and RBF and GFR were measured by the renal vein thermodilution technique and by renal extraction of 51chromium,ethylenediaminetetraacetic acid, respectively. RVO2 and RO2Ex were calculated by arterial and renal vein blood samples. Results: The mean arterial pressure was not affected by vasopressin while cardiac output and heart rate decreased. RBF decreased and GFR, filtration fraction, sodium reabsorption, RVO2, RO2Ex and renal vascular resistance increased dose-dependently with vasopressin. Vasopressin exerted direct antidiuretic and antinatriuretic effects. Conclusions: Short-term infusion of low to moderate, non-hypertensive doses of vasopressin induced a post-glomerular renal vasoconstriction with a decrease in RBF and an increase in GFR in post-cardiac surgery patients. This was accompanied by an increase in RVO2, as a consequence of the increases in the filtered tubular load of sodium. Finally, vasopressin impaired the renal oxygen demand/supply relationship. [source] Power Doppler sonography of the kidney: Effect of Valsalva's maneuverJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2001Ryuichi Takano MD Abstract Purpose It has been reported that an intra-abdominal pressure (IAP) above 15 mm Hg may cause oliguria and that an IAP above 25 mm Hg may cause anuria. Because Valsalva's maneuver yields an IAP exceeding 180 mm Hg, it is presumed to affect renal perfusion. We evaluated the ability of power Doppler sonography to depict the changes in renal blood flow during Valsalva's maneuver. Methods Seven healthy men aged 21,24 years and 1 50-year-old man with massive ascites participated in the study. With each healthy subject lying in a supine position, longitudinal power Doppler sonograms of the kidney were obtained and analyzed semiquantitatively during Valsalva's maneuver. Also, in the patient with massive ascites, power Doppler sonography was performed before and after paracentesis. Results Along with an increase in IAP, monitored as expiratory pressure during Valsalva's maneuver, power Doppler signals decreased as indicated by both visual impression and computer scores. In the patient with massive ascites, signal intensity increased after paracentesis. Conclusions Our results demonstrated that an increase in IAP within the physiologic range affects renal perfusion and that power Doppler sonography depicts semiquantitatively the change in renal blood flow. © 2001 John Wiley & Sons, Inc. J Clin Ultra- 29:384,388, 2001. [source] Effects of Norepinephrine and Combined Norepinephrine and Fenoldopam Infusion on Systemic Hemodynamics and Indices of Renal Function in Normotensive Neonatal FoalsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2008A.R. Hollis Background: Norepinephrine increases arterial blood pressure but may have adverse effects on renal blood flow. Fenoldopam, a dopamine-1 receptor agonist, increases urine output in normotensive foals. The combination of norepinephrine and fenoldopam may lead to improved renal perfusion compared with an infusion of norepinephrine alone. The combined effects of these drugs have not been reported in the horse. Hypothesis: Norepinephrine will alter the hemodynamic profile of foals without affecting renal function. Addition of fenoldopam will change the renal profile during the infusions without changing the hemodynamic profile. Animals: Five conscious pony foals. Methods: Each foal received norepinephrine (0.3 ,g/kg/min), combined norepinephrine (0.3 ,g/kg/min) and fenoldopam (0.04 ,g/kg/min), and a control dose of saline in a masked, placebo-controlled study. Heart rate (HR), arterial blood pressure (direct), and cardiac output (lithium dilution) were measured, and systemic vascular resistance (SVR), stroke volume, cardiac index (CI), and stroke volume index were calculated. Urine output, creatinine clearance, and fractional excretion of electrolytes were measured. Results: Norepinephrine and a combined norepinephrine and fenoldopam infusion increased arterial blood pressure, SVR, urine output, and creatinine clearance and decreased HR and CI compared with saline. The combination resulted in higher HR and lower arterial blood pressure than norepinephrine alone. Conclusions and Clinical Importance: Norepinephrine might be useful for hypotensive foals, because in normal foals, this infusion rate increases SVR without negatively affecting renal function (creatinine clearance increased). Fenoldopam does not provide additional benefit to renal function. These findings warrant further investigation. [source] Fluid resuscitation from severe hemorrhagic shock using diaspirin cross-linked hemoglobin fails to improve pancreatic and renal perfusionACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2004A. Pape Background:, Fluid resuscitation from hemorrhagic shock is intended to abolish microcirculatory disorders and to restore adequate tissue oxygenation. Diaspirin cross-linked hemoglobin (DCLHb) is a hemoglobin-based oxygen carrier (HBOC) with vasoconstrictive properties. Therefore, fluid resuscitation from severe hemorrhagic shock using DCLHb was expected to improve perfusion pressure and tissue perfusion of kidneys and pancreas. Methods:, In 20 anesthetized domestic pigs with an experimentally induced coronary stenosis, shock (mean arterial pressure 45 mmHg) was induced by controlled withdrawal of blood and maintained for 60 min. Fluid resuscitation (replacement of the plasma volume withdrawn during hemorrhage) was performed with either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). Completion of resuscitation was followed by a 60-min observation period. Regional blood flow to the kidneys and the pancreas was measured by use of the radioactive microspheres method at baseline, after shock and 60 min after fluid resuscitation. Results:, All animals (10/10) resuscitated with DCLHb survived the 60-min observation period, while 5/10 control animals died within 20 min due to persisting subendocardial ischemia. In contrast to HSA survivors, pancreas and kidneys of DCLHb-treated animals revealed lower total and regional organ perfusion and regional oxygen delivery. Renal and pancreatic blood flow heterogeneity was higher in the DCLHb group. Conclusion:, DCLHb-induced vasoconstriction afforded superior myocardial perfusion, but impaired regional perfusion of the kidneys and the pancreas. [source] | ||||||||||