ACUTE RENAL FAILURE

DEFINITION

Renal failure is the inability of the kidney to remove the body’s metabolic waste or perform the regulatory functions. The substances normally eliminated in the urine accumulate in the body fluid as a result of impaired renal excretion and leads to a disruption in endocrine and metabolic function as well as fluids, electrolyte and acid-base disturbance.Acute Renal failure is therefore a sudden and almost complete loss of the kidney’s ability to perform its regulatory function or inability to excrete metabolic waste product from the system. 

INCIDENCE

Acute Renal failure occurs to all age groups. It affects people who use nephro-toxic substances like penicillin, methyl alcohol and pesticides. 

CAUSES \ AETIOLOGY

Causes are divided into 3 major categories:

1. Pre – Renal
2. Intra – Renal 
3. Post renal

Pre – Renal Causes 

It is the result of impaired blood flow that leads to hypo perfusion of the kidney and a decrease in the Glomerular Filtration Rate:

1. Hypotension
2. Severe dehydration
3. Haemorrhage
4. Burns
5. Sepsis
6. Cardiogenic shock 
7. Decreased cardiac output
8. Heart failure
9. Obstruction of renal artery by tumour or reduction of blood supply to the kidney.

Intra – Renal \ Renal Causes

It is the result of acute tissue damage to the kidney tissues. Nephrotoxins flow through the tubules, vasoconstriction and changes in glomerular permeability. These processes result in decrease in glomerular filtration rate.

1. Crash injury that affects the kidney
2. Infectious disease
3. Blood transfusion reaction
4. Acute tubular necrosis 
5. Hypocalcemia
6. Glomerular nephritis
7. Pyelonephritis 
8. Renal toxicity
9. Haemolytic anaemia 
10. Prolong renal Ischaemia 
11. Poisonous drugs

Post Renal Causes

It is usually the result of an obstruction somewhere distal to the kidney. Pressure rises in the kidney tubules and eventually glomerular filtration rate decreases.

1. Urinary tract obstruction including tumours and renal calculi
2. Prostatic Hypertrophy
3. Infections in the kidney
4. Bladder obstruction by clot
5. Hydronephrosis

PATHOPHYSIOLOGY

In Acute Renal, there is a sudden or complete loss of kidney function caused by failure of the renal circulation or by glomerular of tubular function. It manifest as an increase in serum creatinine and BUN and retention of other metabolic waste.Urine volume may be normal or changes may occur. Possible changes include Oliguria less than 400 mls per day, non – oliguria greater than 400 mls per day or anuria less than 50 mls per day.

There are four clinical phases of Acute Renal Failure, these are:

1. The initial or onset phase
2. The period of Oliguria
3. The period of diuresis
4. The period of recovery

The Initial \ Onset Phase  

It begins from the precipitating event and ends when Oliguria develops.

The Period of Oliguria

In this period, the urine output less than 400 mls-600 mls per 24 hrs. is accompanied by increase in the concentration of the elements usually excreted by the kidney such as uric acid and sodium. This phase last approximately for 10 days. In some patients, there can be a decrease renal function with increasing nitrogen retention, yet the patient excretes two or more litres of urine daily. This is also called high output failure and occurs predominantly after nephro-toxic antibiotics administration. It may occur in burns, traumatic injury and halogenate anaesthesia. 

The Period of Diuresis

During the period of diuresis, client experiences a gradual increase in urinary output which signals that glomerular function has started to recover.

Although the volume of urinary output may reach normal, there may be abnormal secretion or retention of waste products in the blood. It may not be up to standard therefore medical management may still be important at this stage

The Period of Recovery

The period of recovery signals the improvement of renal function and may last for a period of 3 to 12 months usually; there is a permanent partial reduction in glomerular filtration rate and the kidneys ability to concentrate the urine.

CLINICAL MANIFESTATION

1. Lethargy
2. Nausea and vomiting
3. Diarrhoea
4. Dry skin and mucous membrane
5. Headache
6. Oliguria
7. Anaemia
8. Oedema
9. Petechiae and ecchymoses
10. Haematemesis
11. Abdominal pains
12. Pruritis
13. Drowsiness
14. Tarchypnoea
15. Haemoptysis
16. Haematemesis
17. Low specific gravity of urine (1.010 compared with 1.025 as normal)

DIAGNOSTIC INVESTIGATION

1. Urinalysis to determine the physical properties and chemical composition of urine

a) Physical composition

• Colour of urine
• Specific gravity
• Amount of daily urine
• Odour
• Content

b) Chemical composition

1. Determination of protein, urobilin by assessing creatinine in urine
2. Fasting blood sugar to determine glucose level in the blood to rule out diabetes mellitus.
3. Lipid level investigation to determine the fat content of the blood. 
4. Renal biopsy to histological studies to identify the underlying pathology.
5. Renal function test to assess the kidney function.
6. Haemoglobin level estimation to rule out anaemia.
7. Signs and symptoms exhibited by the client.
8. Radiological examination to assess the anatomical structure of the kidney.

SPECIFIC MEDICAL TREATMENT

The therapeutic goals are focused on the;

1. Control of renal failure.
2. To increase the flow of urine to prevent uraemia.
3. To prevent serious complications.
4. Antiemetic to prevent or relieve gastric irritation.
5. Anti-biotics are administered to treat any infection.
6. Haematinics or iron supplements are used to treat anaemia, example is fersolate tablets.
7. Opiod analgesics to combat pain.
8. Anti-convulsants to relieve convulsions when it occurs.
9. Dialysis -This becomes necessary when client does not respond to medical treatment.

COMPLICATIONS

• Chronic Renal Failure
• Anaemia
• Convulsions
• Pruritis
• Altered mental function
• Cardio pulmonary complications