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Continuing education Activity
Oliguria is a typically encountered clinical condition that can arise due to either prerenal, renal, or post-renal abnormalities. It has actually various etiologies and management is dependency on the underlying cause(s). In bespeak to avoid renal failure, the providers need to not just keep in watch the etiology and management the oliguria but additionally the miscellaneous risk factors and also precipitating components as well. This activity reviews the evaluation and also management that oliguria and highlights the function of the interprofessional team in improving care for patients through this condition.
Identify the etiology the oliguria.
Describe the appropriate evaluation steps for assessing oliguria.
Summarize the management choices for oliguria.
Explain the prominence of collaboration and communication among the interprofessional team come enhance shipment of treatment for patients through oliguria.
Access totally free multiple choice questions top top this topic.
Oliguria is identified as urinary output much less than 400 ml per day or much less than 20 ml every hour and is among the earliest signs of impaired renal function.<1> It had been explained early in the literary works when Hippocrates established the prognostic prominence of the urinary output. It remained in the second century that Galen suggest its definition to indicate renal function.<2> later on on, renal failure accompanied through oliguria was explained by Heberden together ‘ischuria renalis.’<3><4> according to the Acute Dialysis high quality Initiative group, a patient with urinary output <0.3 ml/kg/h because that at least 24 hours deserve to be identified to be oliguric.<5>
Oliguria deserve to be the an outcome of various causes that deserve to be apparent or subclinical.<1> Oliguria have the right to arise together a an outcome of the normal physiological response of the body or as result of an basic pathology influence the kidney or urinary tract. The human being body has a typical physiological device of conserving fluids and also electrolytes in episodes of hypovolemia. This mechanisms space under close neurohormonal control and are totally reversible without any subsequent injury to the kidneys.<6> The miscellaneous etiologic factors can be extensively classified right into prerenal, renal, and also postrenal causes depending upon the pathophysiology.
Hypovolemia: lessened effective blood volume secondary to less fluid intake, bleeding, gastrointestinal liquid loss (diarrhea, vomiting, or nasogastric suction), renal casualty (diuretics or glycosuria), third-spacing of fluid (ascites, pleural effusion), trauma, surgery, burns, sepsis, anaphylaxis, hepatic failure, nephrotic syndrome, vasodilatory medicine or anesthetic agents.
Pump Failure: Myocardial failure secondary to myocardial infarction, pulmonary embolism, cardiac tamponade, and congestive love failure.
Vascular: Renal-artery or renal-vein occlusion as result of thrombosis, thromboembolism, significant stenosis, disrupted renal autoregulation an additional to the administration of angiotensin-converting–enzyme (ACE) inhibitors.
Renal or Intrinsic Causes:
Vasculitis, glomerulonephritis, scleroderma, malignant hypertension, or interstitial nephritis.
Acute tubular necrosis (ATN) as result of ischemia and also nephrotoxic substances, including drugs (e.g., gentamicin, kanamycin, mercury, cisplatin), radiographic comparison agents.
Upper urinary tract obstruction as result of ureteral obstruction the one or both sides.
In the postoperative course, as a an outcome of the release of vasopressin and the sorry stimulation, transient oliguria might be observed.<3><7>
Oliguria is a frequently prevalent problem in hospitalized patients and requires close follow up.<8> Episodes the oliguria room observed in nearly fifty percent of patients admitted to the intensive care unit (ICU).<3><9> Chronic oliguria is typically seen in patient on lengthy term dialysis.<8>
The most usual prerenal cause is decreased blood flow to the kidney secondary to intravascular volume depletion, love failure, sepsis, or as a side result of medication. Oliguria an additional to prerenal causes usually resolves with the restoration of typical renal perfusion. Together a result of the reduced renal blood flow, assorted neurohormonal pathways are activated, that an outcome in the increased production the renin, angiotensin, aldosterone and catecholamines and also prostaglandins. Activation of this pathways leads to boosted water and also salt reabsorption resulting in the production of low quantities of focused urine while maintaining adequate glomerular filtration rate (GFR) and renal blood circulation (RBF) to fulfill the metabolic requirements of the kidneys. In case fluid corrections room not done, decremental reduce in GFR and RBF will an outcome in acute renal failure (ARF).
Renal reasons of oliguria arise as a an outcome of tubular damage. As a result of the tubular damage, the kidney loser its normal duty i.e., production of urine while excreting the rubbish metabolites. In addition to this, direct damages to the renal tubules leads to a earlier leak of filtered uremic metabolites native the tubular lumen right into the bloodstream. Hence, in these cases, lessened production of urine leader to oliguria.
In post-renal causes, urine production is normal, yet as a an outcome of one obstruction in the urinary tract, urine output is significantly diminished.<8>
History and also Physical
In a patient with oliguria, a detailed history is required with a focus on past medical background (diabetes, hypertension, love disease, autoimmune disease, etc.), family history as well together the present medications (potential nephrotoxins).
The patient must be inquired about their occupation, hobbies, and recent take trip as well. A thorough physical exam must be carried out to assess the hydration status of the patience (skin turgor, mucous membranes) as hemodynamic status can aid in the to know of pre-renal reasons of oliguria. Alternate episodes that oliguria and polyuria allude towards a diagnosis of intermittent urinary tract obstruction.<1> Palpation of the urinary bladder might reveal a distended bladder an additional to urinary retention in acute cases. A bedside urinary bladder ultrasound may also be helpful and also can instantaneously determine if there is the retention the urine.
After a detailed history is obtained and thorough physics examination is performed, baseline investigative workup need to be done, consisting of serum creatinine, urea, serum electrolytes, and also blood urea nitrogen. In enhancement to these, urine analysis should it is in done together with a renal tract/abdominal ultrasound. To pee collection need to be done prior to fluid replacement and drug administration.<1> details cases require specific laboratory investigations, consisting of an autoimmune file (ANA, ANCA, complement levels).<3> An urgent and proper examination of the patient with oliguria is crucial in order to identify any type of potentially reversible precipitating factor. Notice investigation and correction protect against the development of the patience to a state the acute renal failure the is linked with its very own risks as well as greater morbidity and also mortality.<10> The testimonial of the hemodynamic standing of the patient might require invasive surveillance of the main venous push (CVP) or the pulmonary capillary wedge push in instances where the measurements cannot be done v non-invasive methods. Together invasive monitoring might be necessary in more critically ill patients.
Urinalysis can assist in separating the reasons of oliguria as well. The particular gravity the the pee is >1.02 in prerenal and also <1.01 in renal causes. Urinary salt concentration (mmol/liter) value is <20 in prerenal reasons whereas it is >40 in renal etiologies. Similarly, fractional excretion of salt (%) is <1% in prerenal and >1% in renal causes. The ratio of urinary to plasma creatinine is >40 in prerenal causes, vice versa, <20 in renal causes. To pee osmolality is >500 in prerenal and <350 in renal etiologies, and the ratio of urine come plasma osmolarity is >1.5 in prerenal and <1.1 in renal etiologies.<11> The blood urea nitrogen (BUN) come creatinine ratio is >20:1 in prerenal an illness and <10:1 in renal diseases.<8>
It is because of the reality that the resorptive abilities of the kidney stay normal in prerenal causes. Urinary sediments have the right to also assist in differentiating the prerenal and renal reasons of oliguria. Pee samples indigenous patients through prerenal failure regularly have hyaline and also fine-granular casts, vice versa, brown granular casts v tubular epithelial cells room seen in patients through renal causes.<1>
Renal ultrasound through doppler of renal vasculature can aid in the evaluate of renal perfusion with the Doppler-based renal resistive index (RI). Imaging, consisting of renal street ultrasound and also CT scan that the abdomen, can help in the identification of the post-renal reasons of oliguria. In situations of obstructive uropathy, dilatation that the urinary tract may or may not it is in present. The dilatation is specifically absent in situations with malignancy, serious dehydration, and also the patients who current early for clinical attention.<1>
Treatment / Management
A stepwise method is encourage in the diagnosis and also treatment that patients through oliguria. Therapy depends mainly on the underlying etiology.
In post renal reasons of oliguria, attention must be command to basic etiology. Sometimes only basic measures are required to control those causes, because that example, catheter irrigation in instance of a clogged urinary catheter, or manipulation in instance of a kinked catheter, etc. A bedside bladder ultrasound may be valuable to finding urinary retention and also to overview if an indwelling urinary catheter is needed. A urology consultation could be valuable in situations of urinary retention because of BPH, tumors, or stones.
The very first step is the hemodynamic stabilization that the patient. The lot of fluid is calculation on an separation, personal, instance basis.<1> It must be provided that return hemodynamic stabilization is necessary, volume overloading have to be avoided at all costs and also treated with diuresis or renal replacement treatment if indicated.<12> Starch commodities can cause tubular damage and also hence have to be avoided. For a huge volume replacement, well balanced crystalloids are recommended. The target for hemodynamic stabilization is afford the typical arterial push (MAP) the 65-70 mmHg in non-hypertensive patients. In addition to every the therapeutic modalities, nearby hourly monitoring of urine calculation is extremely important to gauge therapy accordingly.<3>
If liquid resuscitation fails to settle the oliguria, diuretic therapy have to be initiated making use of a standardized approach. A furosemide stress test (FST) deserve to be done in stimulate to assess the patient’s response to diuresis. It need to be provided that a diuretic difficulty should just be given once the patient is euvolemic. Fail of resolution the oliguria v the above step(s) should raise uncertainty for review for acute kidney injury (AKI). FST is a standardized test to evaluate the practical integrity of the tubules and aids in the threat stratification as well as decision making. FST is said to be nonresponsive if 1.0-1.5 mg/kg that furosemide produces a urine output of 100 ml/h in the very first two hours. Nonresponsive FST is connected with a higher stage the AKI. Part studies suggest using 100-200 mg of furosemide initially, and also if over there is no response, doubling the dose may be considered. If this falls short to bring any far-ranging improvement including a thiazide diuretic can also be considered.<1>
One the the most essential prerequisites that FST is the the patient need to not be hypovolemic, and also the love rate, as well as the blood pressure, have to be carefully monitored. A recent study has shown that 75% that the patients who room nonresponsive to FST require renal replacement treatment as compared to just 13.6% of patient who space FST responsive.<13> A patient responsive come diuretics need to be regulated accordingly.<3><14> If diuretic therapy stops working to enhance the clinical condition, it should be discontinued.<1>
Renal replacement Therapy:
In oliguric patients, an additional to renal etiology therapy is mainly focused on donate care and also potential renal replacement treatment to manage the fluid and electrolyte balance to protect against the breakthrough of complications.<1>
In enhancement to concentrating on fluid and also electrolyte management, adequate protein and also caloric intake space necessary. High prices of protein catabolism (200–250 g/day) space observed in patients with ARF, sepsis, or rhabdomyolysis.<1>
The therapy for oliguria need to be ongoing keeping in watch the indict of AKI treatment. All nephrotoxic drugs need to be discontinued, and drugs excreted by the renal device should be closely reviewed, and also their doses need to be adjusted.<3> Drugs metabolized by kidneys need to be avoided. This drugs encompass doxorubicin, allopurinol, aminoglycosides, azathioprine, cephalosporins, clofibrate, digoxin, diazepam, meperidine, procainamide, propoxyphene, propranolol, and also sulfonamides. In situation these drugs room necessary, a dose modification must be done in accordance with the degree of renal injury.<1>
It have to be retained in mind that in the setting of oliguria, fluid resuscitation does put the patient at danger of liquid overload, which subsequently leads to worsening AKI. As a result, overcompensation with fluid is connected with higher mortality as soon as urine calculation is the determining variable for fluid replacement.<15> signs of liquid overload incorporate peripheral edema, enhanced CVP, and also increased IVC diameter.<16><17> In diuretic responsive patient with fluid overload, diuretic medicines are offered to regulate the fluid overload. ~ above the various other hand, in patients who space nonresponsive to diuretics, renal instead of therapy can be used.<3><12>
While examining a patient v oliguria, the adhering to differential diagnosis need to be retained in mind, and also evaluation must be done accordingly:
Pre-renal azotemia: (hemodynamic standing of the patient, urine analysis, and also doppler based renal resistive index).
Oliguria is one of the first indicators that acute renal injury.<8> Oliguric episodes the occur outside the hospital room usually because of a solitary cause and also are largely reversible v a great prognosis. ~ above the various other hand, oliguric patients admitted come the hospitals usually have severe renal insufficiency because of several basic precipitating factors. As a result, they have actually a worse prognosis 보다 that that non-hospitalized patients. Patients admitted in the intensive treatment unit build oliguria later on in the food of their illness and are an additional to multiple body organ failure.<18><19> Hospitalized patients with oliguria have significantly higher morbidity and mortality.<1>
Oliguric patients space at higher risk of emerging acute renal fail (ARF). 30 come 70 percent of patients through ARF build infections the are associated with greater morbidity and also mortality.<1> However, the mortality risk because of oliguria is not fully attributable come the advance of ARF.<4>
The duration and intensity that oliguria have actually a great impact ~ above prognosis. As the intensity of oliguria worsens to <0.5 ml/kg/h, the mortality rises significantly.<4>
In patients v acute oliguria, among the most typical functional derangements that are observed is the sudden loss in the GRF, resulting in acute renal failure. It results in quick increment in plasma urea and also creatinine levels, metabolic acidosis with hyperkalemia, various other electrolyte abnormalities, and volume overload. This warrants an emergency hospital admission for management and also hence avoidance that the cascade the life-threatening events. Life-threatening complications include:
Electrolyte imbalance: Hyperkalemia, metabolic acidosis, salt, and also water retention bring about pulmonary edema, ascites, or pleural effusions, hyperphosphatemia, or hypocalcemia.
Cardiovascular: together a result of the fluid and salt imbalance, congestive love failure, pulmonary edema, and also hypertension generally occur. In part cases, hypotension may be seen, i beg your pardon is a manifestation of various other concomitant illnesses such together sepsis. Electrocardiographic (ECG) changes due to hyperkalemia can be seen. In about a quarter of cases, arrhythmias might occur as result of electrolyte imbalance. Pericarditis is additionally seen rarely and is a manifestation of uremia.
The primary treatment provider should consult a nephrologist because that an experienced opinion and a dietician or nutritionist for advice top top maintaining ideal protein and caloric intake. Radiologist consultation may be forced in stimulate to effectively assess renal perfusion v the Doppler-based renal resistive index (RI).<1> In addition to this, pharmacy top is crucial to look for the potential nephrotoxic impacts of a prescription or any other medication that is mainly renally excreted therefore that ideal dosage modification can it is in made.<20>
Deterrence and also Patient Education
The patient should be educated around the importance of preserving adequate hydration and instructed to avoid the use of any kind of medication there is no consulting the physician, especially NSAIDs, which are one of the typically used medications easily accessible over the respond to for ache relief. The patient should be encourage to follow the provider’s advice and also get regularly complied with up by their physician and a nephrologist if the physician suggests.
Prolonged fasting and also excessive exercise need to be avoided together they have the right to worsen oliguria and can cause rhabdomyolysis. Any kind of catheterized patient should be adequately educated around their catheter care. Security the to pee output is one of the determining components for therapeutic intervention. The patient must be instructed about monitoring the quantity and also appearance of urine. The patient should report any color changes, frothing, and sediment formation. In addition, to focus on fluid and also electrolyte management, sufficient protein and caloric entry is necessary.<1>
Pearls and also Other Issues
PREDISPOSING RISK factors FOR OLIGURIA:<8>
The following components have shown to predispose the patient to the development of oliguria:
Enhancing medical care Team Outcomes
Studies have argued that early on recognition and also management play a an essential role in the prognosis the patients with oliguria; for this reason close monitoring must be excellent in patients through urine output much less than 0.5 ml/kg/hour because that a duration of two consecutive hours.<5>
Radiographic agents provided for various diagnostic imaging studies deserve to precipitate oliguria and acute renal failure, an especially due to their vasoconstrictive impact of renal blood circulation. In a catheterized patience presenting with oliguria, catheter dysfunction should be ruled out.<21> Oliguric episodes in hospitals space usually associated with volume depletion, peri-operative course, diagnostic procedures, and also medications.<1>
Special treatment should be taken to avoid any type of potential nephrotoxic medicine to a patient v oliguria. These drugs include yet are not limited to nonsteroidal anti-inflammatory medicine (NSAIDs), aminoglycosides, radiographic comparison agents, basic anesthetics, angiotensin-converting–enzyme (ACE) inhibitors, amphotericin B, and numerous chemotherapeutic drugs.
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<20> In enhancement to every the therapeutic modalities, close, hourly security of urine calculation is extremely necessary to gauge treatment.<3>