Definition of Renal Failure

Renal failure, otherwise known as kidney failure, is a medical condition whereby the kidneys are no longer able to perform their functions properly.

Kidneys are vital to our health as they regulate the removal of metabolic waste products from our bodies. Waste products in different parts of our bodies are extracted by the kidneys into the bloodstream. These waste products then travel through the ureter to the bladder and are excreted from our bodies through urine.

Failure of the kidneys to carry out their role will result in the accumulation of metabolic waste in our bodies due to insufficient filtration of the blood. This results in abnormally high levels of nitrogen-containing compounds, such as urea, creatinine, various body waste compounds and other nitrogen-rich compounds in the blood. This build-up is termed as azotemia. Mild azotemia may show little or no symptoms. However, if renal failure continues to deteriorate, symptoms will start to develop and lead to a severe condition termed as uremia.

Renal function can be measured by the glomerular filtration rate (GFR). However, in clinical practice, creatinine clearance or estimates of creatinine clearance based on the serum creatinine levels are used to measure GFR. Creatinine is a break-down product of creatine phosphate in muscles.

We are actually able to survive with a single healthy kidney since the amount of renal tissue in one kidney is more than necessary to maintain homeostatic functions and keep us alive. However, when there is a great decrease in the amount of functioning renal tissues, renal failure occurs.

Renal failure is generally divided into 2 types: 

• Acute Kidney Injury (AKI) 

• Chronic Kidney Disease (CKD)

Acute Kidney Injury (AKI)

Acute kidney injury (AKI) is a rapid or abrupt decline in renal filtration function. The signs occur suddenly and can be very severe. There are numerous cases for AKI and depending on the severity of the condition, it may lead to other complications. AKI can be reversible.

Causes of AKI

There are numerous causes of AKI which are commonly divided into the following  4 categories:

1.  Prerenal Failure, an adaptive response to severe volume depletion and hypotension, with structurally intact nephrons, affecting the flow of blood before it reaches the kidneys.

Prerenal failure is the most common type of acute renal failure (60%-70% of all cases). The kidneys do not receive enough blood to filter. Prerenal failure can be caused by the following conditions:

• Dehydration: - From vomiting, diarrhea, water pills, or blood loss
  
• Disruption of blood flow to the kidneys from a variety of cause
  
  
  • Drastic drop in blood pressure from major surgery with blood loss, severe injury infection in the bloodstream (sepsis) causing blood vessels to inappropriately relax or burns 
  • Blockage or narrowing of a blood vessel carrying blood to the kidneys
  • Heart failure or heart attacks causing low blood flow  
  • Liver failure causing changes in hormones that affect blood flow and pressure to the kidney

There is no actual damage to the kidneys early in the process with prerenal failure. With appropriate treatment, the dysfunction usually can be reversed. Prolonged decrease in the blood flow to the kidneys, for whatever reason, can however cause permanent damage to the kidney tissues

2.  Intrinsic, in response to cytotoxic, ischemic, or inflammatory insults to the kidneys, with structural and functional damage. 

3.  Postrenal Failure, from obstruction to the passage of urine, affecting the movement of urine out of the kidneys.

Postrenal failure is sometimes referred to as obstructive renal failure, since it is often caused by something blocking elimination of urine produced by the kidneys. It is the rarest cause of acute kidney failure (5%-10% of all cases). This problem can be reversed, unless the obstruction is present long enough to cause damage to kidney tissue.

Obstruction of one or both ureters can be caused by the following:

• Kidney stone: usually only on one side
  
  
• Cancer of the urinary tract organs or structures near the urinary tract that may obstruct the outflow of urine
  
  
• Medications

Obstruction at the bladder level can be caused by the following:

• Bladder stone
  
  
• Enlarged prostate (the most common cause in men)
  
  
• Blood clot
  
  
• Bladder cancer
  
  
• Neurologic disorders of the bladder impairing its ability to contract

Treatment consists of relieving the obstruction. Once the blockage is removed, the kidneys usually recover in one to two weeks if there is no infection or other problem.

4.  Renal Damage, problems with the kidney itself that prevent proper filtration of blood or production of urine.

Primary renal damage is the most complicated cause of renal failure (accounts for 25%-40% of cases). Renal causes of acute kidney failure include those affecting the filtering function of the kidney, those affecting the blood supply within the kidney, and those affecting the kidney tissue that handles salt and water processing.

Some kidney problems that can cause kidney failure include:

• Blood vessel diseases
  
  
• Blood clot in a vessel in the kidneys
  
  
• Injury to kidney tissue and cells
  
  
• Glomerulonephritis
  
  
• Acute interstitial nephritis
  
  
• Acute tubular necrosis 

Prevalence of AKI

The reported prevalence of AKI from US data ranges from 1% (community-acquired) up to 7.1% (hospital-acquired) of all hospital admissions. A clear understanding of the true incidence of AKI is dependent on the population being studied and the criteria used to define AKI. The population incidence from UK data ranges from 172 per million population (pmp) per year from early data up to 486-630 pmp/year from more recent series, again depending on definition. The incidence of AKI requiring renal replacement therapy (RRT) ranged from 22 pmp/year up to 203 pmp/year. An estimated 5-20% of critically ill patients experience an episode of AKI during the course of their illness and AKI requiring RRT has been reported in 4·9% of all admissions to intensive-care units. Data from the Intensive Care National Audit Research Centre suggests that AKI accounts for nearly 10 percent of all ICU bed days.

Symptoms of AKI

There are several symptoms of AKI, including:

• loss of blood which leads to a drop in blood pressure
• vomiting and diarrhoea which causes dehydration
• crush injuries, which may cause the release of toxic protein substance harmful to the kidneys when large amounts of muscles are damaged 
• sudden blockage of urine drainage

Diagnosis of AKI

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 function, as measured by serum creatinine, or based on a rapid reduction in urine output, termed oliguria.

Definition

Introduced by the Acute Kidney Injury Network (AKIN), specific criteria exist for the diagnosis of AKI:

1. Rapid time course (less than 48 hours) 
2. Reduction of kidney function 

• 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 

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 function for more than 4 weeks

• End-stage renal disease: complete loss of kidney function for more than 3 months 

Further testing

Once the diagnosis of AKI is made, further testing is often required to determine the underlying cause. These may include renal ultrasound and kidney biopsy. Indications for renal biopsy in the setting of AKI include:

1. Unexplained AKI 
2. AKI in the presence of the nephritic syndrome 
3. Systemic disease associated with AKI

Treatment of AKI

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 ibuprofen, iodinated contrasts 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.

Specific therapies

In prerenal AKI without fluid overload, 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, inotropes 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.

Diuretic agents

The use of diuretics such as furosemide, while widespread and sometimes convenient in ameliorating fluid overload, does not reduce the risk of complications or death. In practice, diuretics may simply mask things, making it more difficult to judge the adequacy of resuscitation.

Renal replacement therapy

Renal replacement therapy, 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.

Prognosis for AKI patients

The prognosis of patients with AKI is directly related to the cause of renal failure and, to a great extent, to the duration of renal failure prior to therapeutic intervention. If AKI is defined by a sudden increment of serum creatinine of 0.5-1 mg/dL and is associated with a mild to moderate rise in creatinine, the prognosis tends to be worse. However, even if renal failure is mild, the mortality rate is 30-60%. If these patients need dialytic therapy, the mortality rate is 50-90%.

>  The mortality rate is 31% in patients with normal urine sediment test results and is 74% in patients with abnormal urine sediment test results.

>  The survival rate is nearly 0% among patients with AKI who have an Acute Physiology and Chronic Health Evaluation II (APACHE II) score higher than 40; the survival rate is 40% in patients with APACHE II scores of 10-19.

>  Other prognostic factors include the following:

• Older age
• Multiorgan failure (ie, the more organs that fail, the worse the prognosis)
• Oliguria 
• Hypotension 
• Vasopressor support 
• Number of transfusions 
• Noncavitary surgery 

>  Prerenal azotemia due to volume contraction is treated with volume expansion; if left untreated for a prolonged duration, tubular necrosis may result and may not be reversible.

>  Postrenal AKI, if left untreated for a long time, may result in irreversible renal damage. Procedures such as catheter placement, lithotripsy, prostatectomy, stent placement, and percutaneous nephrostomy can help to prevent permanent renal damage. 

>  Timely identification of pyelonephritis, proper treatment, and further prevention using prophylactic antibiotics may improve the prognosis, especially in females.

• Early diagnosis of crescentic glomerulonephritis via renal biopsy and other appropriate tests may enhance early renal recovery because appropriate therapy can be initiated promptly and aggressively.
• The number of crescents, the type of crescents (ie, cellular vs fibrous), and the serum creatinine level at the time of presentation may dictate prognosis for renal recovery in this subgroup of patients.

Possible complications of AKI

People suffering from AKI may develop complications such as metabolic acidosis, hyperkalemia, and pulmonary edema. If there's insufficient improvement in the condition, artificial support in the form of dialysis or hemofiltration will be required. Depending on the cause, a proportion of patients may fail to regain renal function and will proceed to develop end-stage renal failure. 

Chronic Kidney Disease (CKD)

Healthy kidneys function to remove metabolic waste products from our bodies. Chronic kidney disease occurs when the kidneys are no longer able to effectively remove these waste products, which will lead to their accumulation in our bodies. Chronic kidney disease (CKD) is a progressive deterioration of renal function over a long period of time, usually spanning months or years. CKD is irreversible.

Based on the part of the renal anatomy that is involved, CKD can be divided into 5 categories:

1. Vascular disease
2. Primary glomerular disease
3. Secondary glomerular disease
4. Tubulointerstitial disease
5. Urinary tract obstruction

Causes of CKD

Chronic renal failure develops over months and years. The most common causes of chronic renal failure are related to:

* poorly controlled diabetes,

* poorly controlled high blood pressure, and

* chronic glomerulonephritis.

Diabetic nephropathy, hypertension and glomerulonephritis are responsible for approximately 75% of adult cases of CKD.

Less common causes of chronic renal failure include:

* polycystic kidney disease,

* reflux nephropathy,

* kidney stones, and

* prostate disease.

Prevalence of CKD

How Common is Chronic Kidney Disease?

Chronic kidney disease is a growing health problem in global. A report by the Centers for Disease Control (CDC) determined that 16.8% of all adults above the age of 20 years have chronic kidney disease. Thus, one in six individuals has kidney disease. By disease stage, the prevalence is as follows:

• Stage 1, 3.1%
  
• Stage 2, 4.1%
  
• Stage 3, 7.6%
  
• Stage 4, 3.2 %
  
• Stage 5, 0.5% 

• The prevalence of chronic kidney disease has increased by 16% from the previous decade. The increasing incidence of diabetes, hypertension (high blood pressure), obesity, and an aging population have contributed to this increase in kidney disease.
  
• Chronic kidney disease is more prevalent among individuals above 60 years of age (39.4%).
  
• Kidney disease is more common among Hispanic, African American, Asian or Pacific Islander, and Native American people.

Symptoms of CKD

If you experience any of the following symptoms (more than two) listed below, you are most likely suffering from CKD : 

•  High blood pressure
•  Itching and dryness of the skin
•  Poor concentration, confusion , forgetfulness
•  Shortness of breath
•  Urination problems, such as foamy or bloody urine, more or less urine than usual or a change in how   often you urinate
•  Swelling in the hands, feet, or face, especially upon waking up
•  A metallic or other foreign taste in your mouth 
•  Loss of appetite
•  Nausea pain in the small of the back in the area of the kidneys upon pressure 
•  Often restless or cramped legs

        Foamy Urine                                   Bloody Urine: Gross hematuria &
                                                                     Microscopic hematuria

 P.S : If you have more than one or more symptoms listed here, it is advisable to see your family doctor or do a full body medical check up.

Treatment of CKD

The treatment of CKD essentially aims to slow down or stop the progress of CKD to stage 5. Management principally includes the control of blood pressure and treatment of the original disease, whenever feasible. Generally, angiotensin converting enzyme inhibitors (ACEIs) or angiotensin II receptor antagonists (ARBs) are used, as they have been found to slow the progression of CKD to stage 5. However, patients who are on these medications will gradually lose renal function.

Replacement of erythropoietin and vitamin D3, two hormones processed by the kidney, is usually necessary in patients with CKD, as is calcium. Serum phosphate levels of patients with CKD are usually elevated so phosphate binders are needed to control the high levels of serum phosphate.

In some cases, dietary modifications have been proven to slow and even reverse further progression. Generally this includes limiting a persons intake of protein.

If CKD proceeds to stage 5, then the only option left is renal replacement therapy, either in the form of dialysis or kidney transplant.

Prognosis for CKD patients

The outlook for patients with CKD is bleak. Data as shown that as renal function drops, mortality rate increases. Regardless of whether there is progression to stage 5, cardiovascular disease is the leading cause of death in patients with CKD,

If CKD progress to stage 5, then renal replacement therapy is the only option. Kidney transplant will significantly increase the survival of patients but it poses the risk of an increased short-term death rate due to the complications of the surgery. Dialysis can maintain the lives of patients, but  it poses a stress on the patients' quality of life. High intensity home hemodialysis appears to be associated with improved survival and a greater quality of life, when compared to the conventional three times a week hemodialysis and peritoneal dialysis.

Possible complications of CKD

People with CKD are at risk of developing various complications and comorbidities, including cardiovascular diseases, respiratory system infections, bone and muscle problems, and anaemia. These problems can begin at a very early stage, even before CKD is detected, and the risks increase with the severity of CKD.

Dialysis

Dialysis is essential for many renal failure patients whose kidneys are no longer able to function normally. Without dialysis to assist them in removing the waste products from their bodies, the afflicted patients will die very fast due to the accumulation of toxins in the blood stream. The lives of patients can be prolonged for many years through dialysis.

Dialysis is generally divided into 2 types: Hemodialysis and Peritoneal dialysis.

Conclusion

The form of dialysis to be undertaken by the patient is based upon the patient's individual condition and their personal medical history, among other issues. Both types of dialysis have their own benefits and complications so the nephrologist (kidney specialist) will usually discuss with the patient and family before deciding on the best option to take.

Hemodialysis

Hemodialysis (haemodialysis)

-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 can be an Inpatient or Outpatient therapy.

•  Inpatient is conducted in a dialysis outpatient facility, either a purpose built room in a hospital or a dedicated, stand alone clinic.Dialysis treatments in a clinic are initiated and managed by specialized staff made up of nurses and technicians
•  Outpatient is done at home and can be self initiated and managed or done jointly with the assistance of a trained helper who is usually a family member.

Hemodialysis uses a machine filter called a dialyzer or artificial kidney to remove excess water and salt, to balance the other electrolytes in the body, and to remove waste products of metabolism. Blood is removed from the body and flows through a tubing into the machine, where it passes next to a filter membrane. A specialized chemical solution (dialysate) flows on the other side of the membrane. The dialysate is formulated to draw impurities from the blood through the filter membrane. Blood and dialysate never touch in the artificial kidney machine.

For this type of dialysis, access to the blood vessels needs to be surgically created so that large amounts of blood can flow into the machine and back to the body. Surgeons can build a fistula, a connection between a large artery and vein in the body, usually in the arm, that causes a large amount of blood flow into the vein. This makes the vein larger and its walls thicker so that it can tolerate repeated needle sticks to attach tubing from the body to the machine. Since it takes many weeks for a fistula to mature enough to be used, significant planning is required if hemodialysis is to be considered as an option.

If the kidney failure happens acutely and there is no time to build a fistula, special catheters may be inserted into the larger blood vessels of the arm, leg, or chest. These catheters may be left in place for up to three weeks. In some diseases, the need for dialysis will be temporary, but if the expectation is that dialysis will continue for a prolonged period of time, these catheters act as a bridge until a fistula can be planned, placed, and matured.

There are 3 types of hemodialysis:

Conventional hemodialysis

The patient is attached to a dialysis machine which pushes blood to circulate through the patient’s body and machine, while at the same time monitor temperature, blood pressure and time of the procedure. If the patient is using a fistula or graft, two huge-gate needles on the patients’ side will be planted: one brings blood containing waste products from the patients’ body to the dialyzer, while another needle carries clean blood back to the body. It is offered three times a week and 3 or 4 hours per session. Patients are required to follow their rigid schedule.

Daily hemodialysis

The procedure of daily hemodialysis is similar to the conventional hemodialysis except it is performed six days a week and about 2 hours per session.

Nocturnal hemodialysis

The procedure of nocturnal hemodialysis is similar to conventional hemodialysis except it is performed six nights a week and 6 to 10 hours per session while the patient sleeps.

Peritoneal Dialysis

ritoneal Dialysis (PD)

-is a treatment for patients with severe chronic kidney failure. The process uses the patient's peritoneum in the abdomen as a membrane across which fluids and dissolved substances (electrolytes, urea, glucose, albumin and other small molecules) are exchanged from the blood. Fluid is introduced through a permanent tube in the abdomen and flushed out either every night while the patient sleeps (automatic peritoneal dialysis) or via regular exchanges throughout the day (continuous ambulatory peritoneal dialysis). PD is used as an alternative to hemodialysis though it is far less common.

 Disadvantage

-It has comparable risks and expenses, with the primary advantage being the ability to undertake treatment without visiting a medical facility. The primary complication with PD is a risk of infection due to the presence of a permanent tube in the abdomen.

Peritoneal dialysis uses the lining of the abdominal cavity as the dialysis filter to rid the body of waste and to balance electrolyte levels. A catheter is placed in the abdominal cavity through the abdominal wall by a surgeon and is expected to remain there for the long-term. The dialysis solution is then dripped in through the catheter and left in the abdominal cavity for a few hours and then is drained out. In that time, waste products leech from the blood normally flowing through the lining of the abdomen (peritoneum).

There are 2 major types of peritoneal dialysis:

Continuous Ambulatory Peritoneal Dialysis (CAPD)

The patient does not attach to a machine and exchange happens manually with gravity. The dialysis happens continuously for 24 hours a day and 7 days a week with dwell time lasting 3 to 5 hours. There are about 4 exchanges daily with each exchange taking about 30 mins.

Continuous Cycling Peritoneal Dialysis (CCPD)

The patient is attached to a machine called “cycler” which accomplish the exchange automatically based on pre-programmed settings. The patient is attached to the machine during the night when they sleep and this one-time exchange lasts for 8 to 10 hours.

Kidney Transplant

If kidney failure occurs and is non-reversible, kidney transplantation is an alternative option to dialysis. If the patient is an appropriate candidate, the health care practitioner will contact an organ transplant center to arrange evaluation to see if the patient is suitable for this treatment. If so, the search for a donor begins. Sometimes, family members have compatible tissue types and, if they are willing, may donate a kidney. Otherwise, the patient will be placed on the waiting list.

Not all hospitals are capable of performing kidney transplants. The patient may have to travel to undergo their operation. The most successful programs are those that do many transplants every year.

While kidney transplants have become more routine, they still carry some risk. The patient will need to take anti-rejection medications that reduce the ability of the immune system to fight infection. The body can try to reject the kidney or the transplanted kidney may fail to work. As with any operation, there is a risk of bleeding and infection.

Kidney transplants may provide better quality of life than dialysis. After one year, 95% of transplanted kidneys are still functioning and after five years the number is 80%. It seems that the longer a patient is on dialysis, the shorter the life of the transplanted kidney.

If the transplanted kidney fails, the alternative is another kidney transplant or a return to dialysis.

References

http://www.medicinenet.com/

http://en.wikipedia.org/wiki/

http://www.webmd.com/

http://medlineplus.gov/

http://en.wikipedia.org/wiki/Peritoneal_dialysis

http://www.youtube.com/watch?v=CDBNmgkIqMs

http://singapore.renalinfo.com/how_kidneys_work_and_fail/kidney_failure/symptoms_of_kidney_failure/index.html

http://www.hkma.org/english/cme/onlinecme/cme200804set.htm

http://www.buzzle.com/articles/renal-failure-stages.html

http://www.emedicinehealth.com/chronic_kidney_disease/page3_em.htm#Common