Acute renal failure
Encyclopedia
Acute kidney injury previously called acute renal failure (ARF), is a rapid loss of kidney function
. Its causes are numerous and include low blood volume
from any cause, exposure to substances harmful to the kidney, and obstruction of the urinary tract. AKI is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen
and creatinine
, or inability of the kidneys to produce sufficient amounts of urine
. AKI may lead to a number of complications, including metabolic acidosis
, high potassium levels, uremia, changes in body fluid balance
, and effects to other organ systems. Management includes supportive care, such as renal replacement therapy
, as well as treatment of the underlying disorder.
, headache
, nausea
and vomiting
. Marked increases in the potassium
level can lead to irregularities in the heartbeat, which can be severe and life-threatening. Fluid balance
is frequently affected, though hypertension
is rare.
Pain in the flanks may be encountered in some conditions (such as thrombosis
of the renal blood vessels or inflammation of the kidney); this is the result of stretching of the fibrous tissue capsule surrounding the kidney
. If the kidney injury is the result of dehydration, there may be thirst
as well as evidence of fluid depletion on physical examination
. Physical examination may also provide other clues as to the underlying cause of the kidney problem, such as a rash
in interstitial nephritis and a palpable bladder
.
Finally, inability to excrete sufficient fluid from the body can cause accumulation of fluid in the limbs (peripheral edema
) and the lungs (pulmonary edema
), as well as cardial tamponade as a result of fluid effusion
s.
. These include systemic causes, such as low blood volume
, low blood pressure
, and heart failure, as well as local changes to the blood vessels supplying the kidney. The latter include renal artery stenosis
, which is a narrowing of the renal artery
that supplies the kidney, and renal vein thrombosis
, which is the formation of a blood clot
in the renal vein
that drains blood from the kidney.
Renal ischaemia ultimately results in functional disorder, depression of GFR, or both. These causes the inadequate cardiac output and hypovolemia or vascular diseases causing reduced perfusion of both kidneys.
, or interstitium. Common causes of each are glomerulonephritis
, acute tubular necrosis
(ATN), and acute interstitial nephritis (AIN), respectively.
, kidney stone
s, obstructed urinary catheter, bladder stone, bladder, ureteral or renal malignancy. It is useful to perform a bladder scan or a post void residual to rule out urinary retention. In post void residual, a catheter is inserted immediately after urinating to measure fluid still in the bladder. 50-100ml suggests neurogenic bladder. A renal ultrasound will demonstrate hydronephrosis if present. A CT scan of the abdomen will also demonstrate bladder distension or hydronephrosis, however, in case of acute renal failure, the use of IV contrast is contraindicated. On the basic metabolic panel, the ratio of BUN to creatinine may indicate post renal failure.
s for substances normally eliminated by the kidney: urea
and creatinine
. Both tests have their disadvantages. For instance, it takes about 24 hours for the creatinine level to rise, even if both kidneys have ceased to function. A number of alternative markers has been proposed, but none are currently established enough to replace creatinine as a marker of renal function.
Sodium and potassium, two electrolytes that are commonly deranged in people with acute kidney injury, are typically measured together with urea and creatinine.
, as measured by serum creatinine
, or based on a rapid reduction in urine output, termed oliguria
.
, iodinated contrast
s such as those used for CT scans, and others.
Monitoring of renal function, by serial serum creatinine measurements and monitoring of urine output, is routinely performed. In the hospital, insertion of a urinary catheter
helps monitor urine output and relieves possible bladder outlet obstruction, such as with an enlarged prostate.
, administration of intravenous fluids is typically the first step to improve renal function. Volume status may be monitored with the use of a central venous catheter
to avoid over- or under-replacement of fluid.
Should low blood pressure
prove a persistent problem in the fluid-replete patient, inotrope
s such as norepinephrine
and dobutamine
may be given to improve cardiac output
and hence renal perfusion. While a useful pressor, there is no evidence to suggest that dopamine
is of any specific benefit, and may be harmful.
The myriad causes of intrinsic AKI require specific therapies. For example, intrinsic AKI due to Wegener's granulomatosis
may respond to steroid
medication. Toxin-induced prerenal AKI often responds to discontinuation of the offending agent, such as aminoglycoside
, penicillin
, NSAIDs, or acetaminophen.
If the cause is obstruction of the urinary tract, relief of the obstruction (with a nephrostomy
or urinary catheter) may be necessary.
, while widespread and sometimes convenient in ameliorating fluid overload, does not reduce the risk of complications or death.
, such as with hemodialysis
, may be instituted in some cases of AKI. A systematic review of the literature in 2008 demonstrated no difference in outcomes between the use of intermittent hemodialysis and continuous venovenous hemofiltration (CVVH). Among critically ill patients, intensive renal replacement therapy with CVVH does not appear to improve outcomes compared to less intensive intermittent hemodialysis.
, hyperkalemia
, and pulmonary edema
may require medical treatment with sodium bicarbonate
, antihyperkalemic measures, and diuretics.
Lack of improvement with fluid resuscitation
, therapy-resistant hyperkalemia, metabolic acidosis, or fluid overload may necessitate artificial support
in the form of dialysis
or hemofiltration
.
.
was the term used to describe the contamination of the blood
with urine
. Starting around 1847 this term was used to describe reduced urine output, now known as oliguria
, which was thought to be caused by the urine's mixing with the blood instead of being voided through the urethra
.
Acute kidney injury due to acute tubular necrosis
(ATN) was recognised in the 1940s in the United Kingdom
, where crush injury
victims during the London Blitz developed patchy necrosis of renal tubules, leading to a sudden decrease in renal function. During the Korean
and Vietnam wars
, the incidence of AKI decreased due to better acute management and administration of intravenous fluids.
Renal function
Renal function, in nephrology, is an indication of the state of the kidney and its role in renal physiology. Glomerular filtration rate describes the flow rate of filtered fluid through the kidney...
. Its causes are numerous and include low blood volume
Hypovolemia
In physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma...
from any cause, exposure to substances harmful to the kidney, and obstruction of the urinary tract. AKI is diagnosed on the basis of characteristic laboratory findings, such as elevated blood urea nitrogen
Blood urea nitrogen
The blood urea nitrogen test is a measure of the amount of nitrogen in the blood in the form of urea, and a measurement of renal function. Urea is a by- product from metabolism of proteins by the liver and is removed from the blood by the kidneys.-Physiology:The liver produces urea in the urea...
and creatinine
Creatinine
Creatinine is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body...
, or inability of the kidneys to produce sufficient amounts of urine
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...
. AKI may lead to a number of complications, including metabolic acidosis
Metabolic acidosis
In medicine, metabolic acidosis is a condition that occurs when the body produces too much acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low due to increased production of hydrogen by the body or the...
, high potassium levels, uremia, changes in body fluid balance
Fluid balance
Fluid balance is the concept of human homeostasis that the amount of fluid lost from the body is equal to the amount of fluid taken in. Euvolemia is the state of normal body fluid volume. Water is necessary for all life on Earth...
, and effects to other organ systems. Management includes supportive care, such as renal replacement therapy
Renal replacement therapy
Renal replacement therapy is a term used to encompass life-supporting treatments for renal failure.It includes:*hemodialysis,*peritoneal dialysis,*hemofiltration and*renal transplantation.These treatments will not cure chronic kidney disease...
, as well as treatment of the underlying disorder.
Signs and symptoms
The symptoms of acute kidney injury result from the various disturbances of kidney function that are associated with the disease. Accumulation of urea and other nitrogen-containing substances in the bloodstream lead to a number of symptoms, such as fatigue, loss of appetiteAnorexia (symptom)
Anorexia is the decreased sensation of appetite...
, headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
, nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
and vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
. Marked increases in the potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
level can lead to irregularities in the heartbeat, which can be severe and life-threatening. Fluid balance
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
is frequently affected, though hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
is rare.
Pain in the flanks may be encountered in some conditions (such as thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
of the renal blood vessels or inflammation of the kidney); this is the result of stretching of the fibrous tissue capsule surrounding the kidney
Renal capsule
The renal capsule is a tough fibrous layer surrounding the kidney and covered in a thick layer of perinephric adipose tissue. It provides some protection from trauma and damage....
. If the kidney injury is the result of dehydration, there may be thirst
Thirst
Thirst is the craving for fluids, resulting in the basic instinct of animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids and/or an increase in the concentration of certain osmolites, such as salt...
as well as evidence of fluid depletion on physical examination
Physical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
. Physical examination may also provide other clues as to the underlying cause of the kidney problem, such as a rash
Rash
A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...
in interstitial nephritis and a palpable bladder
Urinary bladder
The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
.
Finally, inability to excrete sufficient fluid from the body can cause accumulation of fluid in the limbs (peripheral edema
Peripheral edema
Peripheral edema is the swelling of tissues, usually in the lower limbs, due to the accumulation of fluids.The condition is commonly associated with aging, but can be caused by many other conditions, including congestive heart failure, trauma, alcoholism, altitude sickness, pregnancy,...
) and the lungs (pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
), as well as cardial tamponade as a result of fluid effusion
Effusion
In physics, effusion is the process in which individual molecules flow through a hole without collisions between molecules. This occurs if the diameter of the hole is considerably smaller than the mean free path of the molecules...
s.
Causes
The one cause of acute kidney injury are commonly categorised into prerenal, intrinsic, and postrenal.| Type | UOsm | UNa | FeNa | BUN/Cr |
|---|---|---|---|---|
| Prerenal | >500 | <10 | <1% | >20 |
| Intrinsic | <350 | >20 | >2% | <15 |
| Postrenal | <350 | >40 | >4% | >15 |
Prerenal
Prerenal causes of AKI ("pre-renal azotemia") are those that decrease effective blood flow to the kidneyRenal blood flow
In the physiology of the kidney, renal blood flow is the volume of blood delivered to the kidneys per unit time. In humans, the kidneys together receive roughly 22% of cardiac output, amounting to 1.1 L/min in a 70-kg adult male...
. These include systemic causes, such as low blood volume
Hypovolemia
In physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma...
, low blood pressure
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
, and heart failure, as well as local changes to the blood vessels supplying the kidney. The latter include renal artery stenosis
Renal artery stenosis
Renal artery stenosis is the narrowing of the renal artery, most often caused by atherosclerosis or fibromuscular dysplasia. This narrowing of the renal artery can impede blood flow to the target kidney...
, which is a narrowing of the renal artery
Renal artery
The renal arteries normally arise off the side of the abdominal aorta, immediately below the superior mesenteric artery, and supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle with the aorta....
that supplies the kidney, and renal vein thrombosis
Renal vein thrombosis
Renal vein thrombosis is the formation of a clot or thrombus obstructing the renal vein, leading to a reduction in drainage of the kidney.-Presentation:This thrombosis can lead to imbalances in blood clotting factor...
, which is the formation of a blood clot
Thrombus
A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...
in the renal vein
Renal vein
The renal veins are veins that drain the kidney. They connect the kidney to the inferior vena cava.It is usually singular to each kidney, except in the condition "multiple renal veins".It also divides into 2 divisions upon entering the kidney:...
that drains blood from the kidney.
Renal ischaemia ultimately results in functional disorder, depression of GFR, or both. These causes the inadequate cardiac output and hypovolemia or vascular diseases causing reduced perfusion of both kidneys.
Intrinsic
Sources of damage to the kidney itself are dubbed intrinsic. Intrinsic AKI can be due to damage to the glomeruli, renal tubulesNephron
The renal tubule is the portion of the nephron containing the tubular fluid filtered through the glomerulus. After passing through the renal tubule, the filtrate continues to the collecting duct system, which is not part of the nephron....
, or interstitium. Common causes of each are glomerulonephritis
Glomerulonephritis
Glomerulonephritis, also known as glomerular nephritis, abbreviated GN, is a renal disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys...
, acute tubular necrosis
Acute tubular necrosis
Acute tubular necrosis or is a medical condition involving the death of tubular cells that form the tubule that transports urine to the ureters while reabsorbing 99% of the water . Tubular cells continually replace themselves and if the cause of ATN is removed then recovery is likely...
(ATN), and acute interstitial nephritis (AIN), respectively.
Postrenal
Postrenal AKI is a consequence of urinary tract obstruction. This may be related to benign prostatic hyperplasiaBenign prostatic hyperplasia
Benign prostatic hyperplasia also known as benign prostatic hypertrophy , benign enlargement of the prostate , and adenofibromyomatous hyperplasia, refers to the increase in size of the prostate....
, kidney stone
Kidney stone
A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...
s, obstructed urinary catheter, bladder stone, bladder, ureteral or renal malignancy. It is useful to perform a bladder scan or a post void residual to rule out urinary retention. In post void residual, a catheter is inserted immediately after urinating to measure fluid still in the bladder. 50-100ml suggests neurogenic bladder. A renal ultrasound will demonstrate hydronephrosis if present. A CT scan of the abdomen will also demonstrate bladder distension or hydronephrosis, however, in case of acute renal failure, the use of IV contrast is contraindicated. On the basic metabolic panel, the ratio of BUN to creatinine may indicate post renal failure.
Detection
The deterioration of renal function may be discovered by a measured decrease in urine output. Often, it is diagnosed on the basis of blood testBlood test
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....
s for substances normally eliminated by the kidney: urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
and creatinine
Creatinine
Creatinine is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body...
. Both tests have their disadvantages. For instance, it takes about 24 hours for the creatinine level to rise, even if both kidneys have ceased to function. A number of alternative markers has been proposed, but none are currently established enough to replace creatinine as a marker of renal function.
Sodium and potassium, two electrolytes that are commonly deranged in people with acute kidney injury, are typically measured together with urea and creatinine.
Further testing
Once the diagnosis of AKI is made, further testing is often required to determine the underlying cause. These may include urine sediment analysis, renal ultrasound and/or kidney biopsy. Indications for renal biopsy in the setting of AKI include:- Unexplained AKI
- AKI in the presence of the nephritic syndromeNephritic syndromeNephritic syndrome is a collection of signs associated with disorders affecting the kidneys, more specifically glomerular disorders. It is characterized by having small pores in the podocytes of the glomerulus, large enough to permit proteins and red blood cells to pass into the urine...
- Systemic disease associated with AKI
Classification
Acute kidney injury is diagnosed on the basis of clinical history and laboratory data. A diagnosis is made when there is rapid reduction in kidney functionRenal function
Renal function, in nephrology, is an indication of the state of the kidney and its role in renal physiology. Glomerular filtration rate describes the flow rate of filtered fluid through the kidney...
, as measured by serum creatinine
Creatinine
Creatinine is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body...
, or based on a rapid reduction in urine output, termed oliguria
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...
.
Definition
Introduced by the Acute Kidney Injury Network (AKIN), specific criteria exist for the diagnosis of AKI:- Rapid time course (less than 48 hours)
- Reduction of kidney function
- Rise in serum creatinineCreatinineCreatinine is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body...
- Absolute increase in serum creatinine of ≥0.3 mg/dl (≥26.4 μmol/l)
- Percentage increase in serum creatinine of ≥50%
- Reduction in urine output, defined as <0.5 ml/kg/hr for more than 6 hours
- Rise in serum creatinine
Staging
The RIFLE criteria, proposed by the Acute Dialysis Quality Initiative (ADQI) group, aid in the staging of patients with AKI:- Risk: serum creatinine increased 1.5 times or urine production of <0.5 ml/kg for 6 hours
- Injury: doubling of creatinine or urine production <0.5 ml/kg for 12 hours
- Failure: tripling of creatinine or creatinine >355 μmol/l (with a rise of >44) (>4 mg/dl) OR urine output below 0.3 ml/kg for 24 hours
- Loss: persistent AKI or complete loss of kidney functionRenal functionRenal function, in nephrology, is an indication of the state of the kidney and its role in renal physiology. Glomerular filtration rate describes the flow rate of filtered fluid through the kidney...
for more than 4 weeks - End-stage renal disease: complete loss of kidney function for more than 3 months
Treatment
The management of AKI hinges on identification and treatment of the underlying cause. In addition to treatment of the underlying disorder, management of AKI routinely includes the avoidance of substances that are toxic to the kidneys, called nephrotoxins. These include NSAIDs such as ibuprofenIbuprofen
Ibuprofen is a nonsteroidal anti-inflammatory drug used for relief of symptoms of arthritis, fever, as an analgesic , especially where there is an inflammatory component, and dysmenorrhea....
, iodinated contrast
Iodinated contrast
Iodinated contrast is a form of intravenous radiocontrast containing iodine, which enhances the visibility of vascular structures and organs during radiographic procedures...
s such as those used for CT scans, and others.
Monitoring of renal function, by serial serum creatinine measurements and monitoring of urine output, is routinely performed. In the hospital, insertion of a urinary catheter
Urinary catheterization
In urinary catheterization , a latex, polyurethane or silicone tube known as a urinary catheter is inserted into a patient's bladder via his or her urethra. Catheterization allows the patient's urine to drain freely from the bladder for collection. It may be used to inject liquids used for...
helps monitor urine output and relieves possible bladder outlet obstruction, such as with an enlarged prostate.
Specific therapies
In prerenal AKI without fluid overloadHypervolemia
Hypervolemia, or fluid overload, is the medical condition where there is too much fluid in the blood.The opposite condition is hypovolemia, which is too little fluid volume in the blood.-Causes:Excessive sodium or fluid intake:* IV therapy...
, administration of intravenous fluids is typically the first step to improve renal function. Volume status may be monitored with the use of a central venous catheter
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...
to avoid over- or under-replacement of fluid.
Should low blood pressure
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
prove a persistent problem in the fluid-replete patient, inotrope
Inotrope
An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions...
s such as norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
and dobutamine
Dobutamine
Dobutamine is a sympathomimetic drug used in the treatment of heart failure and cardiogenic shock. Its primary mechanism is direct stimulation of β1 receptors of the sympathetic nervous system. Dobutamine was developed by a laboratory led by Drs...
may be given to improve cardiac output
Cardiac output
Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...
and hence renal perfusion. While a useful pressor, there is no evidence to suggest that dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
is of any specific benefit, and may be harmful.
The myriad causes of intrinsic AKI require specific therapies. For example, intrinsic AKI due to Wegener's granulomatosis
Wegener's granulomatosis
Wegener's granulomatosis , more recently granulomatosis with polyangiitis , is an incurable form of vasculitis that affects the nose, lungs, kidneys and other organs. Due to its end-organ damage, it is life-threatening and requires long-term immunosuppression...
may respond to steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
medication. Toxin-induced prerenal AKI often responds to discontinuation of the offending agent, such as aminoglycoside
Aminoglycoside
An aminoglycoside is a molecule or a portion of a molecule composed of amino-modifiedsugars.Several aminoglycosides function as antibiotics that are effective against certain types of bacteria...
, penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....
, NSAIDs, or acetaminophen.
If the cause is obstruction of the urinary tract, relief of the obstruction (with a nephrostomy
Nephrostomy
A nephrostomy is an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system ....
or urinary catheter) may be necessary.
Diuretic agents
The use of diuretics such as furosemideFurosemide
Furosemide or frusemide is a loop diuretic used in the treatment of congestive heart failure and edema. It is most commonly marketed by Sanofi-Aventis under the brand name Lasix...
, while widespread and sometimes convenient in ameliorating fluid overload, does not reduce the risk of complications or death.
Renal replacement therapy
Renal replacement therapyRenal replacement therapy
Renal replacement therapy is a term used to encompass life-supporting treatments for renal failure.It includes:*hemodialysis,*peritoneal dialysis,*hemofiltration and*renal transplantation.These treatments will not cure chronic kidney disease...
, such as with hemodialysis
Hemodialysis
In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy...
, may be instituted in some cases of AKI. A systematic review of the literature in 2008 demonstrated no difference in outcomes between the use of intermittent hemodialysis and continuous venovenous hemofiltration (CVVH). Among critically ill patients, intensive renal replacement therapy with CVVH does not appear to improve outcomes compared to less intensive intermittent hemodialysis.
Complications
Metabolic acidosisMetabolic acidosis
In medicine, metabolic acidosis is a condition that occurs when the body produces too much acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low due to increased production of hydrogen by the body or the...
, hyperkalemia
Hyperkalemia
Hyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...
, and pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
may require medical treatment with sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...
, antihyperkalemic measures, and diuretics.
Lack of improvement with fluid resuscitation
Fluid replacement
Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced via oral administration , intravenous administration, rectally, or hypodermoclysis, the direct injection...
, therapy-resistant hyperkalemia, metabolic acidosis, or fluid overload may necessitate artificial support
Renal replacement therapy
Renal replacement therapy is a term used to encompass life-supporting treatments for renal failure.It includes:*hemodialysis,*peritoneal dialysis,*hemofiltration and*renal transplantation.These treatments will not cure chronic kidney disease...
in the form of dialysis
Dialysis
In medicine, dialysis is a process for removing waste and excess water from the blood, and is primarily used to provide an artificial replacement for lost kidney function in people with renal failure...
or hemofiltration
Hemofiltration
In medicine, hemofiltration, also haemofiltration, is a renal replacement therapy similar to hemodialysis which is used almost exclusively in the intensive care setting...
.
Prognosis
Depending on the cause, a proportion of patients will never regain full renal function, thus having end-stage renal failure requiring lifelong dialysis or a kidney transplant.Epidemiology
Acute kidney injury is common among hospitalized patients. It affects some 3-7% of patients admitted to the hospital and approximately 25-30% of patients in the intensive care unitIntensive Care Unit
thumb|220px|ICU roomAn intensive-care unit , critical-care unit , intensive-therapy unit/intensive-treatment unit is a specialized department in a hospital that provides intensive-care medicine...
.
History
Before the advancement of modern medicine, acute kidney injury might be referred to as uremic poisoning. UremiaUremia
Uremia or uraemia is a term used to loosely describe the illness accompanying kidney failure , in particular the nitrogenous waste products associated with the failure of this organ....
was the term used to describe the contamination of the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
with urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
. Starting around 1847 this term was used to describe reduced urine output, now known as oliguria
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...
, which was thought to be caused by the urine's mixing with the blood instead of being voided through the urethra
Urethra
In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...
.
Acute kidney injury due to acute tubular necrosis
Acute tubular necrosis
Acute tubular necrosis or is a medical condition involving the death of tubular cells that form the tubule that transports urine to the ureters while reabsorbing 99% of the water . Tubular cells continually replace themselves and if the cause of ATN is removed then recovery is likely...
(ATN) was recognised in the 1940s in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, where crush injury
Crush syndrome
Crush syndrome is a medical condition characterized by major shock and renal failure after a crushing injury to skeletal muscle...
victims during the London Blitz developed patchy necrosis of renal tubules, leading to a sudden decrease in renal function. During the Korean
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...
and Vietnam wars
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
, the incidence of AKI decreased due to better acute management and administration of intravenous fluids.
See also
- BUN-to-creatinine ratioBUN-to-creatinine ratioIn medicine, the BUN-to-creatinine ratio is the ratio of two serum laboratory values, the blood urea nitrogen and serum creatinine . Outside the United States, particularly in Canada and Europe, the truncated term urea is used and the units are different...
- Chronic kidney disease
- DialysisDialysisIn medicine, dialysis is a process for removing waste and excess water from the blood, and is primarily used to provide an artificial replacement for lost kidney function in people with renal failure...
- Renal failureRenal failureRenal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
- RhabdomyolysisRhabdomyolysisRhabdomyolysis is a condition in which damaged skeletal muscle tissue breaks down rapidly. Breakdown products of damaged muscle cells are released into the bloodstream; some of these, such as the protein myoglobin, are harmful to the kidneys and may lead to kidney failure...