Under oliguria refers to a urine production of <500 ml in 24 h in adults or <0.5 ml / kg / h for adults and children (<1 ml / kg / h in neonates). Etiology The causes of oliguria are typically divided into three categories: prerenal (by blood flow dependent) renal (intrinsic renal disease) post-renal (flow disorders) Although there are many such diseases (acute kidney injury (AKI)), yet only a limited number leads causes an acute oliguria (see table: causes of oliguria). Causes of oliguria mechanism examples prerenal * hypovolemia circulation fluid loss Inadequate hydration Low cardiac output heart failure myocardial infarction pulmonary embolism Decreased systemic vascular resistance sepsis Renal Acute tubular necrosis hypoperfusion (for a long time, for. B.> 4 h) X-ray contrast media rhabdomyolysis Nephrotoxic drugs (eg. As aminoglycosides and other antibiotics, NSAIDs) Post Renal Mechanical urinary obstruction Blocked urinary catheter prostatic urinary bladder or Sphinkterdysfunktion use of anticholinergics Postoperative urinary retention Stuhleinklemmung if serious * often overlap these factors and thus quickly (eg. as in <1 h) to decrease in urine production. Clarification history When communicative patients of painful urinary retention an indication of problems with drainage. Thirst no signs of urinary retention contrast, suggests a lack of volume. When subdued, possibly previously catheterized patients showing a sudden decrease in urine output without circulatory dysregulation, to an occlusion (z. B. due to thrombus or kinking) must be thought or dislocation of the catheter. A gradual decrease in urine production, however, occurs because more of acute tubular necrosis (ATN, Acute tubular necrosis) or prerenal cause forth. Abnormalities in the recent history are often revealing. The recorded blood pressure, surgical procedures, medication or performing contrast examinations should be considered. made recently surgery or trauma may be associated with hypovolemia. Massive crush injuries, deep burns in the context of electrical accidents or heatstroke raise suspicion of rhabdomyolysis nahe.Körperliche Exam Vital signs are checked, particularly with respect to hypotension, tachycardia, or both (suggesting hypovolemia or sepsis what) and fever (which sepsis suggests). Signs of herd infection and heart failure should be carefully followed. A palpable Harnblasendistension indicates an outflow obstruction. Deep brown coloration of the urine can be found in Myoglobinurie.Tests In all catheterized patients (as well as with those that are supplied with an ileal conduit), the openness of the urinary tract by the catheter wash up must be ensured. Only after further investigation steps should be taken. In many of the remaining patients the etiology (eg. As shock, sepsis) is clinically obvious. Only in such patients who may present many problems, further investigations into the differential diagnosis of prerenal renal cause (acute tubular necrosis) are required. In patients without bladder catheter, placement of the catheter should be considered. This measure is used to diagnose and treat the obstruction and provides a continuous monitoring of production safe. PCWP or in pulmonary artery wedge pressure (pulmonary arterial wedge pressure (pulmonary capillary wedge pressure: if a central venous or pulmonary artery catheter (PAC) is present, the volume status (also cardiac output with a PAC), by measuring the central venous pressure (end-point and monitoring Intravenous fluid replacement) , pulmonary artery occlusion pressure, PAOP)) are determined respectively. Nevertheless, it will certainly not create these invasive catheter due solely to a Oligurie without further interference. In patients without evidence of volume overload, alternatively, a quantity of about 500 ml of a 0.9% NaCl solution may easily be administered intravenously (20 mL / kg in children). If this leads to an increase in cardiac output, a pre-renal cause is likely. Laboratory tests should be performed. Serum electrolytes, urea and creatinine are based diagnostics. Often the concentrations of sodium and creatinine are determined in urine. In prerenal disorders on the other hand produces mostly a urea / creatinine ratio of> 20, in the normal case and also in ATN of ? 10. In prerenal problems, the urine sodium concentration is <20 mEq / L, since the kidneys highest possible sodium content retinieren to maintain the intravascular volume. In acute tubular necrosis, the sodium concentration in the urine is usually> 40 mEq / L. The proportion of the precipitated sodium (sodium Exkretionsfraktion, FENa) may be represented more specifically by the ability of the kidneys to the retention of sodium and is defined Clinical computer as follows: percentage of excreted sodium shows a ratio <1 indicates that the kidneys are capable of reabsorption of sodium , Thus, the problem is settled prerenal. A ratio of> 3 on the other hand indicates a probably renal failure. Therapy Are revealed the responsible causes, can be treated accordingly. A discharge failure is corrected, a volume deficit compensated normalized cardiac output. The supply of nephrotoxic drugs should be discontinued. Such agents are to be replaced by others. Hypotension it is in any case to avoid to prevent kidney infarcts. Renal failure patients who show no signs of improvement have, a renal replacement therapy (eg. As continuous veno-venous hemofiltration or hemodialysis) are supplied. Summary Among the causes of oliguria include a decreased renal blood flow, renal failure and a urinary tract obstruction. History and physical examination can often be the mechanism suspect (z. B. recently occurred hypotension, use of nephrotoxic agents). Serum electrolytes, BUN and creatinine should be measured. In addition, sodium concentration in urine and of creatinine are to be determined, and the amount of sodium excreted is to be calculated, if it is unclear whether the cause is prerenal or renal. A ratio <1 indicates that the problem has a prerenal cause, while a ratio> 3 indicating a likely cause of renal.