Pathophysiology of hemodynamically mediated acute renal failure in man

Pathophysiology of hemodynamically mediated acute renal failure in man. A tubular injury characterized by intraluminal obstruction and transtubular backleak of glomerular filtrate occurs in experimental acute renal failure (ARF) in animals. To determine whether these alterations also occur in human ARF, we studied 44 patients developing nonoliguric ARF following cardiac surgery. The delay in appearance of i.v. administered inulin in urine (Tu) was used as a measure of tubular fluid flow rate. Tu was not longer in 13 ARF patients than it was in control subjects (7.2 vs. 9.0min), suggesting that at least a subpopulation of tubules was widely patent. The fractional urinary dextran clearance profile (θD; radii, 20 to 40 Å) was then determined in 20 patients with sustained ARF in whom inulin clearance averaged 11 ± 1ml/min/1.73m2. A mass conservation model, which assumes that θD in Bowman's space in ARF is the same as that measured in controls, when applied to the experimental observations revealed that, on the average, 42% of filtered inulin was lost by transtubular backleak. A similar fractional inulin backleak (38%) persisted in 11 additional patients in whom ARF had begun to recover and in whom inulin clearance averaged 26 ± 3ml/min/ 1.73m2. These findings suggest that in hemodynamically-mediated and nonoliguric ARF, (1) tubular obstruction is not homogeneous, and (2) backleak of glomerular filtrate contributes to but does not fully account for depression of inulin clearance. Physiopathologie de l'insuffisance rénale aiguë à médiation hémodynamique chez l'homme. Une lésion tubulaire caractérisée par l'obstruction intraluminale et la fuite trans-tubulaire de filtrat glomérulaire survient au cours de l'insuffisance rénale aiguë (ARF) expérimentale chez l'animal. Afin de savoir si ces modifications surviennent aussi au cours de l'ARF humaine, 44 malades atteints d'ARF non oligurique au décours de la chirurgie cardiaque ont été étudiés. Le délai d'apparition dans l'urine de l'inuline injectée par voie intraveineuse (Tu) a été utilisé comme mesure du débit tubulaire. Tu n'était pas supérieur chez 13 malades en ARF aux valeurs des contrôles (7,2 vs. 9,0min) ce qui suggère qu'au moins une sous-population de tubules était largement perméable. Le profil d'excrétion fractionnelle de dextran (θD; rayons, 20 à 40 Å) a été déterminé chez 20 malades atteints d'ARF chez lesquels la clearance de l'inuline était en moyenne de 11 ± 1ml · min/1,73m2. Un modèle de conservation