Severe post‐renal acute kidney injury, post‐obstructive diuresis and renal recovery

Abstract

E 1 0 2 7What ' s known on the subject? and What does the study add?The pathophysiology of post-renal acute kidney injury (PR-AKI), i.e. caused by urinary tract obstruction, has been extensively studied in animal models but clinical studies on this subject are outdated, and/or have focused on the mechanisms of ' post-obstructive diuresis ' (POD), a potentially life-threatening polyuria that can develop after the release of obstruction.In severe PR-AKI, the risk of occurrence of POD is high. POD occurrence predicts renal recovery without the persistence of severe chronic kidney failure. In the present study, the occurrence of POD and the persistence of chronic renal sequelae could be predicted early from clinical variables at admission before the release of obstruction. OBJECTIVE• To identify predictors of post-obstructive diuresis (POD) occurrence or severe chronic renal failure (CRF) persistence after the release of urinary tract obstruction in the setting of post-renal acute kidney injury (PR-AKI). PATIENTS AND METHODS• Bi-centre retrospective observational study of all patients with PR-AKI treated in two intensive care units (ICUs) from 1998 to 2010.• Clinical, biological and imaging characteristics on admission and after the release of obstruction were analysed with univariate and, if possible, multivariate analysis to search for predictors of (i) occurrence of POD (diuresis > 4 L/day) after the release of obstruction; (ii) persistence of severe CRF (estimated glomerular fi ltration rate < 30 mL/ min/1.73 m 2 , including end-stage CRF) at 3 months. RESULTS• On admission, median (range) serum creatinine was 866 (247 -3119) μ mol/L.• POD occurred in 34 (63%) of the 54 analysable patients. On admission, higher serum creatinine (Odds ratio [ OR ] 1.002 per 1 μ mol/L, 95% confi dence interval [ CI ] 1.000 -1.004, P = 0.004), higher serum bicarbonate (OR 1.36 per 1 mmol/L, 95% CI 1.13 -1.65, P < 0.001), and urinary retention (OR 6.96, 95% CI 1.34 -36.23, P = 0.01) independently predicted POD occurrence.• Severe CRF persisted in seven (21%) of the 34 analysable patients, including two (6%) cases of end-stage CRF. Predictors of severe CRF persistence after univariate analysis were: lower blood haemoglobin ( P < 0.001) and lower serum bicarbonate ( P = 0.03) on admission, longer time from admission to the release of obstruction ( P = 0.01) and absence of POD ( P = 0.04) after the release of obstruction. CONCLUSIONS• In severe PR-AKI treated in ICU, POD occurrence was a frequent event that predicted renal recovery without severe CRF.• POD occurrence or severe CRF persistence could be predicted early from clinical and biological variables at admission before the release of obstruction. KEYWORDSacute kidney failure , chronic kidney failure , ureteric obstruction , critical illness , polyuria Study Type -Therapy (case series) Level of Evidence 4

1024 Impact of retrograde flexible ureteroscopy and intracorporeal lithotripsy on kidney functional outcomes

“…Alteration of the tubular cells associated with macrophages and myoblasts infiltration lead to the production of cytokines and growth factors which are responsible for renal tubular cell apoptosis. This results in chronic obstructive nephropathy with tubular atrophy and loss of nephrons which are replaced by interstitial fibrosis (11)(12)(13).…”

Renal Impairment in Cirrhosis Unrelated to Hepatorenal Syndrome

“…Close monitoring is required during this stage because excessive urinary losses can lead to hypovolemia and electrolyte disturbance. Hamdi et al (53) reported that 63% of intensive care patients with severe postrenal AKI had POD following release of urinary obstruction. The authors found that POD occurrence was predictive of renal recovery while the absence of POD was predictive of CKD.…”

“…Postrenal impairment due to urinary tract obstruction is an uncommon cause of renal dysfunction, accounting for <1% of AKI cases in cirrhosis and 5% to 10% of AKI cases in the general population (5,(53)(54)(55). The presence of hydronephrosis on imaging differentiates postrenal from prerenal or intrinsic renal causes of kidney dysfunction.…”

“…Urinary tract obstruction has many causes. In a retrospective study of 888 patients admitted to intensive care from 1998 to 2010, Hamdi et al (53) found that malignancy represented one-half of all causes of postrenal AKI. Prostate cancer was the most common malignancy (55%) while pelvic cancers as a group accounted for 90% of all malignancies.…”

Anemia and Long-Term Renal Prognosis in Patients with Post-Renal Acute Kidney Injury of Nonmalignant Cause

“…In this context, a recent bi-center retrospective observational study by Hamdi et al [12] , which aimed to identify predictors of post-obstructive diuresis or persistence of severe chronic renal failure (estimated glomerular filtration rate (eGFR) of <30 ml/min/1.73 m 2 ) at 3 months after the resolution of urinary tract obstruction in the setting of PoR-AKI treated in an intensive care unit, revealed low blood hemoglobin (Hb) level at the diagnosis of PoR-AKI as a predictor of persistent severe chronic renal failure. However, as Hamdi et al [12] described in their report, the study had a small sample size, which did not allow multivariate analysis.…”