ACUTE RENAL FAILURE
Definition
Acute renal failure is a sudden and complete loss of kidney function
(decreased GFR) over a period of hours to days.
Causes
Pre renal causes
Intrarenal causes
Post renal causes
Pre renal causes
Volume depletion
Haemorrhage
Renal loss
GI loss
Impaired cardiac efficiency
Myocardial infarction
Congestive heart failure
Dysrhythmias
Cardiogenic shock
Vasodilatation
Sepsis
Anaphylaxis
Antihypertensive drugs
Drugs that cause vasodilatation
Intra renal causes
Prolonged renal ischemia
Myoglobinemia
Hemoglobinemia
Nephrotoxic agents
Radio opaque contrast agents,ACE inhibitors
Acute infections
Acute pyelonephritis
Acute glomerulo nephritis
Post renal causes
Urinary tract obstructions
Calculi
Tumors
Strictures
Blood clots
Pathophysiology
The main two important mechanisms taking place are tubal cell injury and
disturbances in blood flow.
Tubal cell injury
Caused by ischemia and nephrotoxic agents.
Ischemia causes structural and functional alteration in kidney.
Disturbances in blood flow
Reduced GFR will lead to intra renal vasoconstriction which results in reduced
glomerular and plasma filtration and reduced O2 delivery to the functionally
important tubules in medulla.
Ischemia
Endothelial dysfunction
Tubal cell injury Endothelial dysfunction
Vasoconstriction
Vasoconstriction
Reversible Irreversible
Loss of polarity detachment Necrosis apoptosis
Increased distal obstruction by casts
Sodium delivary Tubular back leak
Increased Increased intra tubular pressure complete tubular flow is decreased
tubuloglomerular
feed back
Chronic renal failure
Reduced GFR
Oliguria
Acute renal failure
Phases of acute renal failure
Initiation period
Begins with the initial insult and ends when oliguria develops.
Period of oliguria
It is occupied by a rise in serum concentration in substances usually excreted by
the kidneys (urea,creatinine,uric acid, sodium,magnesium etc)Hyperkalemia
develops.
Some patients can have a decrease in renal function with increase in nitrogen
retention.they excrete normal amounts of urine (2lt/Day).This is the non oliguric
form of renal failure seen in nephrotoxic ,antibiotics and in burns.
Period of diuresis
Increased output patient may go to dehydration and uremic symptoms can be seen.
Period of recovery
Signals of the improvement of renal function may take 3 to 12 months laboratory
values return to normal levels there may be 1 to 2% of reduction in the GFR which
is not significant.
Clinical manifestations
Decreased urine output, although occasionally urine output remains normal
Fluid retention, causing swelling in legs, ankles or feet
Shortness of breath,breath may have urine odour
Fatigue
Confusion, headache
Nausea
Weakness
Irregular heartbeat
Chest pain or pressure
Seizures or coma in severe cases
Skin ,mucus membrane are dry
Diagnosis
Changes in urine specific gravity
Increased BUN ,creatinine level, hyperkalemia, ABG shows metabolic
acidosis
Anemia due to reduced erythropoietin
blood tests - FBC - normochromic normocytic anaemia; ESR; U+Es
(increased urea and increased creatinine); GFR; glucose (check for DM);
urate; bone profile - reduced calcium, increased phosphate, increased
alkaline phosphatase (renal osteodystrophy); increased parathyroid hormone
(hyperparathyroidism)
urine tests - creatinine clearance; 24 hour urinary protein
o there is no need to collect 24 h urine samples to measure creatinine
clearance in primary care because the estimated GFR can be
calculated (1)
o there is no need to perform 24 h urine collections for the quantitation
of proteinuria in primary care because urine protein:creatinine ratio
can be used to assess proteinuria (1)
Renal imaging - ultrasound - assess renal size and exclude obstruction; renal
size generally small in chronic renal failure but normal or large renal size
may be seen in polycystic kidney disease, diabetes mellitus, asymmetrical
renal vascular disease, myeloma, amyloidosis, systemic sclerosis; other
investigations such as IVU, DTPA scan should be considered
chest X-ray
bone X-rays - may reveal renal osteodystrophy
renal biopsy - this investigation may be undertaken e.g. in patients with
chronic renal failure and normal sized kidneys.
Medical management
Treatments to balance the amount of fluids blood. intravenous (IV)
fluids to balance body fluids. In other cases, acute kidney failure may cause
to have too much fluid, leading to swelling in arms and legs. In these cases,
medications (diuretics) to cause body to expel extra fluids.
Medications to control blood potassium. kidneys aren't properly filtering
potassium from blood, prescribe calcium, glucose or sodium polystyrene
sulfonate (Kionex) to prevent the accumulation of high levels of potassium
in blood. Too much potassium in the blood can cause dangerous irregular
heartbeats (arrhythmias) and muscle weakness.
Medications to restore blood calcium levels. If the levels of calcium in
blood drop too low, recommend an infusion of calcium.
Dialysis to remove toxins from your blood. If toxins build up in blood,
may need temporary hemodialysis — often referred to simply as dialysis —
to help remove toxins and excess fluids from body while kidneys heal.
Dialysis may also help remove excess potassium from body.
Administration of medications
Lifestyle and home remedies
Choose lower potassium foods. dietitian may recommend that to choose
lower potassium foods. High-potassium foods include bananas, oranges,
potatoes, spinach and tomatoes. Examples of low-potassium foods include
apples, cauliflower, peppers, grapes and strawberries.
Avoid products with added salt. Lower the amount of sodium eat each day
by avoiding products with added salt, including many convenience foods,
such as frozen dinners, canned soups and fast foods. Other foods with added
salt include salty snack foods, canned vegetables, and processed meats and
cheeses.
Limit phosphorus. Phosphorus is a mineral found in foods, such as whole-
grain bread, oatmeal, bran cereals, dark-colored colas, nuts and peanut butter.
Too much phosphorus in blood can weaken bones and cause skin itchiness.
Dietitian can give you specific recommendations on phosphorus and how to
limit it in particular situation.
Nursing management
Monitor fluid and electrolyte balance
Monitor serum electrolyte levels.
Careful selection of I.V fluids based on the serum electrolyte levels of
patient.
Monitor cardiac function and musculoskeletal function.
Monitor fluid status by careful attention to fluid intake and out put
Maintain I/O chart.
Reduce metabolic rate
Provide bed rest to reduce exertion and the metabolic rate.
Fever and infection can increase the metabolic rate therefore treat them
promptly.
Promote pulmonary function
Provide assistance to patient to turn and demonstrate deep breathing and
coughing exercises.
Prevent atelectasis and respiratory tract infections.
Prevent infection
Avoid indwelling urinary catheter to prevent infection.
Follow aseptic principles while providing care to patient.
Provide skin care
Provide meticulous skin care.
Advice the patient to take bath with cool water and advice to turn frequently.
Keep the skin clean.
Provide psychological support
Provide assistance to patient and family.
Explain about all the procedures and treatment options.
Complications
Anemia
Bone disease and high phosphorus (hyperphosphatemia)
Heart disease
High potassium (hyperkalemia)
Fluid buildup
