ACUTE RENAL FAILURE DUE TO TUBULAR NECROSIS, IMMEDIATE PROGNOSIS AND COMPLICATIONS

Acute renal failure due to intrinsic renal diseases: review of 1122 cases

In this study we have analyzed incidence, causes and clinical course of ARF due to primary intrarenal disease other than acute tubular necrosis. Thousand hundred and twenty two cases of ARF of diverse etiology were studied over a period of 16 years; July 1984 to Dec, 1999. Surgical ARF 231 (20.6%) were not included in the present study. Intrinsic renal diseases were responsible for ARF in 891 (79.4%) of cases. The most common intrinsic renal diseases 705 (79.4%) causing ARF were ischemic/toxic acute tubular necrosis, but not included in this study. Acute renal failure was related to acute glomerulonephritis (9.3%), acute interstitial nephritis (7%), and renal cortical necrosis in (4.6%) of cases. Therefore intrinsic renal diseases other than ATN were the causative factor for acute renal failure in 186 (20.8%) patients in our study. Crescentic (51.8%) and endocapillary proliferative glomerulonephritis (34.9%), were the main glomerular diseases responsible for ARF and 75.9% of GN was related to infectious etiology. Fifty three percent of acute interstitial nephritis was drug induced and in 25 (40%) patients it was related to an infectious etiology. Renal cortical necrosis due to HUS was observed in 16 (39%) children and majority (76.47%) of the cases had a diarrhoeal prodrome. Obstetrical complications were the main causes (61%) of cortical necrosis in adults with acute renal failure. Thus, intrinsic renal diseases other than ATN were responsible for ARF in 186 (20.8%) cases. Post-infectious glomerulonephritis, acute interstitial nephritis and renal cortical necrosis (complicating HUS in children and obstetrical complications in adult) are the main causes of acute renal failure in our study. Both acute GN and interstitial nephritis had excellent prognosis, however renal cortical necrosis was associated with a very high mortality.

Changes in renal medullary pO2 during water diuresis as evaluated by blood oxygenation level-dependent magnetic resonance imaging: effects of aging and cyclooxygenase inhibition

BACKGROUND

Hypoxia of the renal medulla has been implicated in the development of renal injury, particularly acute renal failure, and its regulation in humans may therefore be relevant to certain renal disorders. Changes in oxygenation of the renal medulla can now be monitored noninvasively with blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI). Using this method, water diuresis has been shown to improve medullary oxygenation in young persons. Urinary excretion of prostaglandin E2 (PGE2) likewise increases during water diuresis in younger but not in older people. We used BOLD MRI to measure the effects of aging and of inhibiting prostaglandin synthetase on the renal response to water diuresis in healthy human subjects.

METHODS

Nine younger (25 to 31 years) and nine older (59 to 79 years) female volunteers were studied with BOLD MRI during antidiuresis in the postabsorptive state and during water diuresis. Simultaneously, urinary excretion of PGE2 was determined. PG synthetase was inhibited by administering ibuprofen.

RESULTS

Renal medullary oxygenation, initially low, greatly improved during diuresis in younger subjects, whereas PGE2 excretion increased. In older women, however, water diuresis elicited no change in oxygenation of renal medulla or PGE2 excretion. Ibuprofen inhibited excretion of PGE2 and blocked the increase in medullary oxygenation normally produced by water diuresis in the young.

CONCLUSIONS

The increase in oxygenation of the renal medulla accompanying water diuresis depends on PGE2 synthesis. Attenuation of renal PGE2 synthesis in older people is probably responsible, at least in part, for the loss of the ability to improve medullary oxygenation that younger subjects possess. Inability to improve renal medullary oxygenation might predispose to hypoxic renal injury in older patients.

Epidemiology of acute renal failure: a prospective, multicenter, community-based study. Madrid Acute Renal Failure Study Group

There are very limited data on overall epidemiology of ARF. It is crucial to know the incidence, etiology and clinical feature of ARF to promote prevention strategies and to implement adequate resources for the management of this entity. During a nine month period, a collaborative prospective protocol with 98 variables was developed to assess all ARF episodes encountered in the 13 tertiary-care hospitals in Madrid, Spain (covering 4.2 million people of over 14 years of age). ARF was considered when a sudden rise in serum creatinine concentration (SCr) to more than 177 mumol/liter was found in patients with normal renal function, or when the sudden rise (50% or more) was observed in patients with previous mild-to-moderate chronic renal failure (SCr < 264 mumol/liter). Of the 748 cases of ARF studied, 665 episodes presented in inhabitants from the Madrid area. This gives an overall incidence of ARF of 209 cases per million population (p.m.p.; 95% CJ 195 to 223). The incidence of acute tubular necrosis (ATN) was 88 cases p.m.p. (95% CI 79 to 97), prerenal ARF 46 p.m.p (95% CI 40 to 52), acute-onset chronic ARF 29 p.m.p. (95% CI 24 to 34), and obstructive ARF 23 p.m.p. (95% CI 19 to 27). The mean age was 63 +/- 17 years. The most frequent causes of ARF were ATN (45%), prerenal (21%), acute-onset chronic renal failure (12.7%) and obstructive ARF (10%). Renal function was normal at admission in 48% of patients who later developed ARF. Mortality (45%) was much higher than that of the other patients admitted (5.4%, P < 0.001). This real outcome correlated extremely well with the expected outcome calculated through out the severity index of ARF (SI) 0.433 +/- 0.246 (mean +/- SD). In 187 cases, mortality was attributed to underlying disease, thus corrected mortality due to ARF was 26.7%. Dialysis was required in 36% of patients, and was associated with a significantly higher SI of ARF (0.57 +/- 0.23 vs. 0.35 +/- 0.19, P < 0.001) and mortality (65.9 vs. 33.2%, P < 0.001). Mortality in patients hemodialyzed with biocompatible synthetic membranes (N = 50) was similar to that observed with cellulosic ones (N = 84; 66% vs. 59.5%, NS). Mortality was higher in patients with coma, assisted respiration, hypotension, jaundice (all P < 0.001) and oliguria (P < 0.02). This study gives, for the first time, the incidence of all forms of ARF in a developed country. ARF is iatrogenically induced at a high rate by modern medicine. Prevention strategies, particularly in the perioperative period, are needed to decrease its impact.

Acute renal failure following hemorrhagic shock: protective and aggravating factors

Acute renal failure following hemorrhagic shock was studied in awake rats. The animals were bled to maintain the mean arterial blood pressure between 40 and 60 mm Hg during 180 min. After this period, the blood was reinfused and the rats were studied 24 h later. Hemorrhagic shock caused a less intensive renal injury than 60-min bilateral renal artery clamping. Renal function in the latter model was worse (p less than 0.05) as shown by serum creatinine (SCr) (0.75 +/- 0.10 vs 1.2 +/- 0.2 mg/dL), blood urea nitrogen (BUN) (26.0 +/- 2.8 vs 53.0 +/- 8.5 mg/dL), fractional excretion of sodium (FENa, %) (0.3 +/- 0.1 vs 1.8 +/- 1.0) and potassium (FEK, %) (41.4 +/- 5.7 vs 76.3 +/- 14.2) and urine/plasma creatine (U/PCr (86.4 +/- 15.7 vs 38.8 +/- 15.5). The rats which received verapamil (10 micrograms/kg/min) prior and during the HS did not show increase in SCr (0.5 +/- 0.06 vs 0.75 +/- 0.1 mg/dL, p less than 0.05). This effect was also observed in the rats which received intravenous allopurinol (40 mg/kg) before HS, SCr did not increase (0.5 +/- 0.04 vs 0.75 +/- 0.1 mg/dL, p = 0.05), suggesting a protective effect of those substances in HS.(ABSTRACT TRUNCATED AT 250 WORDS)

Dialytic therapy of acute renal failure

On the basis of experience with dialysis therapy of 1000 patients with acute renal failure in the years from 1955 to 1985 the most important aspects of the treatment were discussed. The precise incidence of acute renal failure is not known. It seems that a number of patients die without being diagnosed. Dialysis therapy is indicated when blood urea concentration exceeds 30 mmol/L and/or serum potassium concentration is higher than 6.5 mmol/L, when patients are over-hydrated or show first signs of uremia. Hemodialysis remains the gold standard among all methods of blood purification. Catheterization of subclavian veins is the most advantageous access to circulation for hemodialysis. Majority of medical complications due to renal failure as well as technical ones may be avoided. Mortality is still high and has not changed in 30 years in spite of medical and technical improvement of treatment because of higher proportion of patients with uncurable underlying disease and higher age. Therapy of patients with acute renal failure should be centralized. No patient, should die of renal failure and its complications.

Gentamicin and gram-negative bacteremia. A synergism for the development of experimental nephrotoxic acute renal failure

To explore whether bacteremia potentiates gentamicin nephrotoxicity, we injected rats with either 1 X 10(9) Escherichia coli (E. coli), Pseudomonas aeruginosa, or Staphylococcus aureus, and then gave them gentamicin, 100 mg/kg. Renal injury was assessed over the next 24-48 h. Staphylococcus/gentamicin or gentamicin alone induced no renal injury. However, E. coli/gentamicin and Pseudomonas/gentamicin caused acute renal failure (severe azotemia; tubular necrosis; cast formation). This effect was not due to acute reductions in arterial blood pressure or renal blood flow, it could be reproduced by substituting nonviable for viable gram-negative organisms, and it was associated with increased renal gentamicin uptake. E. coli without gentamicin induced only mild azotemia and no tubular necrosis. Endotoxin-tolerant rats were significantly protected against the E. coli/gentamicin nephrotoxic interaction. We conclude that gram-negative bacteremia and gentamicin exert synergistic nephrotoxicities; and that this effect is mediated, at least in part, by endotoxin and in part by increased renal gentamicin uptake.

The assessment of risk factors in 462 patients with acute renal failure

Risk factors associated with the mortality of patients with acute renal failure (ARF) were investigated. This was accomplished by a review of 462 patients with ARF and the utilization of a logistic regression analysis to develop a model that can be used to predict the mortality odds for an ARF patient. The significant risk factors were age, oliguria, pulmonary and cardiovascular complications, jaundice, and hypercatabolism. Based on these factors, our model was able to account for 77% of the mortality associated with ARF.

Acute renal failure

The diagnosis and therapy of acute renal failure should be approached in concert, bearing in mind that more than one cause may co-exist in a patient. Therapy includes reversing prerenal and postrenal failure, removing any nephrotoxins, adjusting drug dosages, correcting acidemia, maintaining good nutritional status, and using dialysis when necessary.