Pathophysiology of hemodynamically mediated acute renal failure in man

Abstract

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 9.0 min), suggesting that at least a subpopulation of tubules was widely patent. The fractional urinary dextran clearance profile (thetaD; radii, 20 to 40 A) was then determined in 20 patients with sustained ARF in whom inulin clearance averaged 11 +/- 1 ml/min/1.73 m2. A mass conservation model, which assumes that thetaD 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 +/- 3 ml/min/1.73 m2. 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.

Pathophysiology and prevention of acute renal failure: the role of the anaesthetist

“…As intra-tubular pressure rises the balance of Starling forces determining GFR are altered such that the hydrostatic pressure across the glomerulus is balanced and ultra-filtration eventually will cease (Figure 3). 33 After obstruction, the damaged tubular wall is exposed to higher intra-tubular pressures and "backleak" of ultrafiltrate out of the tubule into the oedematous interstitium has been documented. 34-35 The ultra-filtrate that leaks into the interstitium is reabsorbed into the circulation.…”

Endothelin induces an increase in renal vascular resistance and a fall in glomerular filtration rate in the rabbit isolated perfused kidney

“…and ventilated with air following surgical tracheal intubation. Frusemide (4 mg), which exerts a protective effect against hypoxic damage to the kidney (Myers & Moran, 1986) (Edwards, 1983) was added to the KHB/AA and urine was collected over 5 min intervals, volume being measured gravimetrically. Urine and perfusate counts were determined and GFR calculated (Ross et al, 1973).…”

Alprostadil attenuates inflammatory aspects and leucocytes adhesion on renal ischemia and reperfusion injury in rats

“…3 Renal insult is mostly related to the magnitude and duration of ischemia, leading to edema and tubule obstruction, mainly after reperfusion, and impaired glomerular filtration. 4 Oxigen free radicals play an important role in the metabolic events involved on ischemic reperfusion insult [5][6][7] , as well as neutrophil recruitment and tubular adhesion, all of them intimately related in the early inflammatory phase 8,9 .…”