Hypoperfusion in the Renal outer Medulla after Injection of Contrast Media in Rats

Abstract

Iso-osmolar and high-osmolar contrast media (CM), at normal and high doses, decrease OMBF, while an extremely high dose of iothalamate may result in an increase. The depression of outer medullary perfusion may have implications for CM-induced acute renal failure in view of the vulnerability of this region to a decrease in oxygen tension.

Renal Parenchymal Hypoxia, Hypoxia Adaptation, and the Pathogenesis of Radiocontrast Nephropathy

“…This group of researchers (24) noted a similar decline in outer medullary regional blood flow, using both laser Doppler needle probes and hydrogen washout techniques; however, at very high volumes of injected radiocontrast, outer medullary regional microcirculation markedly increased (25)(26)(27), as long as NO or prostaglandin synthesis remained intact (25). Thus, so far, the impact of radiocontrast on outer medullary perfusion remains a matter of debate, with the different patterns of response possibly related to the type, volume, and route of administration of the dye.…”

Clinical and Experimental Evidence for Prevention of Acute Renal Failure Induced by Radiographic Contrast Media

“…The RCM-induced decrease in partial oxygen pressure (PaO 2 ) is marked in the outer medulla where thick ascending limbs of Henle's loop exist and PaO 2 depends largely on the activities of electrolytes transport systems located on renal tubular membranes (8,51). It has been demonstrated that several loop diuretics, including furosemide, reduce oxygen consumption by inhibiting Na…”

“…Although little is known about cellular mechanisms underlying radiocontrast nephropathy, direct toxic action on renal tubular cells (renal mechanism) (4 -7) and / or decrease in renal blood flow (pre-renal mechanism) (8,9) have been considered to be involved in the pathogenesis of radiocontrast nephropathy. A number of compounds that improve renal blood flow have been clinically tested for prevention of radiocontrast nephropathy, but most of them were not effective.…”

Estudio epidemiológico prospectivo sobre la nefropatía por contraste en pacientes críticos

“…Algunos estudios con animales han documentado una constricción de los vasos rectos que irrigan la médula externa debida al contraste, y un descenso en el flujo sanguíneo medular, ratio de filtración glomerular, velocidad de los hematíes y de la tensión de oxígeno, junto a un incremento en la agregación de los hematíes (32)(33)(34)(35) . En otro estudio animal, la administración intra-arterial de contraste causa una respuesta bifásica, con un período corto de tiempo de hiperperfusión seguido de vasoconstricción con la consecuente hipoperfusión y, finalmente, restauración del flujo normal en unos minutos (36) .…”

“…En nuestra serie, obtenemos una incidencia de NAC del 13.7% en aquellos pacientes que presentan al menos un factor de riesgo, frente al 8.4% de pacientes que no presentaban ninguno. La administración de diuréticos se relacionó con una mayor incidencia de NAC, probablemente por favorecer la hipoperfusión renal secundaria a hipovolemia, que podría contribuir, junto con la hipoperfusión renal generada por el contraste, al desarrollo de esta entidad (32)(33)(34)(35)(36) . Debemos recordar que la disminución de la perfusión renal ha sido postulada, en el estudio de Nash et al como el principal factor de riesgo de lesión renal aguda en pacientes hospitalizados (52) .…”