Hemodynamic factors in acute renal failure (ARF). Renal blood flow is not luxurious, it results from the metabolic demands of renal medulla and cortex. Within both areas, effective shuntdiffusion for blood gases is present. In the outer medulla, the oxygen supply of the thick ascending limb (TAL)-segments especially those of outer cortical nephrons is limited and tubular demands are regulated by the tubuloglomerular feedback. Thus inflowing tubular fluid into Henle´s loop can be adapted to the oxygen supply of the TAL-segment and its proximal tubule (PCT). This adaption works oscillating, experimentally in the rat with a frequency of

30 mHz (2/min) and can be measured by oscillating of proximal tubular pressures, with a phase lag of distal sodium concentration and by oscillating oxygen pressures measured at the renal surface. A change between aerobic supply to glycolysis at the TAL-segment led via a changed fluid sodium concentration at the macula dense to an adjustment of oxygen consumption considering also the fact, that proximal tubules practically have no anaerobic metabolic reserves. If under ischemic and hypoxic conditions reduction of transport capacity is inadequate, deterioration of proximal tubuli and of TAL-segments may be programmed as the kidney´s answer: acute renal failure (ARF).

Abstract in: Hämodynamische Faktoren beim akuten Nierenversagen (ANV)

H. J. Schurek und O. Johns

Nieren- und Hochdruckkrankheiten 20, 2/1991, p 56-60

There are a few different ways to define AKI. One approach centers around the kidney/renal system: pre-renal (essentially hemodynamic), renal (intrinsic renal injury, such as acute tubular necrosis), and post-renal (bladder outlet obstruction). Another emphasizes functional (reversible) vs histologic (less reversible with pathology shown on biopsy). Though several criteria exist to grade AKI, those from the Kidney Disease Improving Global Outcomes (KDIGO) group are often used as they describe AKI by either creatinine based measures or urine output measures and have prognostic value for development of CKD, ESKD and other important outcomes