By: Dr. Wael Thanoon Younis C.A.B.M.,Mosul college of medicine. Acute kidney injury By: Dr. Wael Thanoon Younis C.A.B.M.,Mosul college of medicine.

This term is used primarily to denote failure of the excretory function of the kidney leading to retention of nitrogenous waste products of metabolism, other renal function fail as the regulation of fluid and electrolytes and the endocrine function. Therefore wide range of clinical manifestation may occur. Renal failure may be classified into: 1- Acute renal failure (ARF) 2- Chronic renal failure

Acute renal failure: Definition: Acute kidney injury(AKI) or acute renal failure (ARF) is defined as sudden, rapid, and usually reversible loss of renal function, which develops over period of days or weeks. Classification of A.R.F: Pre- renal A.R.F 1- Severe extracellular volume depletion {like; gastrointestinal bleeding, severe gastroenteritis, antepartum hemorrhage} 2- Decrease renal perfusion {like heart failure} 3- Renal arterial obstruction {like renal emboli}

B) Renal parenchyma A.R.F 1- Acute tubular necrosis {ATN}(85%) like toxic septic renal failure 2- Tubulointerstital nephritis (10%) mostly drug induced 3- Nephrotoxicity (aminoglycoside , radio- contrast media) 4- Glomerular disease {either primary or component of systemic disease 5%}

C) Post renal A.R.F 1- Intratubular obstruction 2- Intra pelvic and peripelvic obstruction (stage horn stone or kidney stone). 3- Urethral stone (stone, clot, external compression) 4- Bladder outlet obstruction, prostatic hypertrophy.

Established A.R.F Occur due to prolonged severe under perfusion lead to A.T.N, this is the most common cause of A.R.F Two type of A.T.N are recognized: 1- due to ischemia usually follow period of shock during which renal blood flow is generally reduced this is due to swelling of endothelial cell Of glomeruli and edema of interstitial blood flow. 2- Nephrotoxic A.T.N: similar change occur and it is due to direct toxicity of causative agent as gentamycin, amphoteracin B.

Clinical features: Patient present with oliguria (less than 500 ml/day), or anuria (absence of urine) is rare and usually indicates acute U.T obstruction In 20% of cases the urine volume is normal or increased (non- oliguria A.R.F) Excretion is inadequate and plasma urea and creatinine increase Disturbance of water and electrolytes occur hyperkalemia is common and serious. Metabolic acidosis develop unless it is prevented, occurs due to loss of hydrogen ions through vomiting or aspiration of gastric content Hypocalcaemia due to reduced production 1, 25 vit D common.

The patient complain of anorexia, nausea, vomiting, altered conscious level drowsiness, apathy, and confusion, muscle twitching, hiccoughs, fits and coma occur. the respiratory rate increase due to acidosis, pulmonary edema, or respiratory infection Pulmonary edema may result from administration of excessive amounts of fluid and because increase pulmonary capillaries permeability (acute respiratory distress syndrome)

Anemia is common due to excessive blood loss, hemolysis , or decrease erythropoietin There is bleeding tendency due to disordered platelet function and disordered coagulation cascade. Gastro intestinal hemorrhage may occur, although this is less common with effective dialysis and the use of agents that reduce acid secretion Severe infection may complicate acute renal failure because of depressed humeral and cellular immune system.

Management of acute renal failure In established acute renal failure: 1- Control of fluid and electrolyte balance: a) Daily fluid intake should equal urine output plus 500ml, to cover insensible loss. Febrile patient require more. b) Restriction of Na and K. c) Patient should Wight daily and large change in body Wight due to the development of edema or signs of fluid depletion indicate that fluid should be reassessed d) If abnormal loss occur as diarrhea.

2- protein and energy intake: a) In patient whom dialysis to be avoided dietary protein is restricted to about (40 gm/day.) b) To reduce endogenous protein catabolism by giving as much energy as possible in form of fat and carbohydrate c) Patient treated by dialysis may have more protein intake (70 gm/day) d) Parenteral nutrition by may be required because of vomiting or diarrhea

Emergency resuscitation 1-hyperkalemia (when plasma K more than 6 mml/l must be treated to prevent life threatening cardiac arrhythmia 2-If circulatory blood volume is low, it must be corrected by transfusion with appropriate fluid. 3-Patient with pulmonary edema usually require dialysis

Other line of therapy:- 1-Obstruction should be relived urgently 2-Corticosteroid and immunosuppressed drugs are of value in acute renal failure G.N and tubule-interstitial nephritis. 3-control of blood pressure is very important in malignant hypertension 4-pelvic or urethral obstruction may need percutaneous nephrostomy.

Recovery of acute renal failure This is usually indicated by gradual return of urine output and then steady improvement of plasma biochemistry towards normal Patient with ATN and after relive of U.T obstruction develop diuretic phase and fluid should be giving to replace the loss with NaCl and NaHCO3, after few day the urine volume falls to normal.

Prognosis:- In uncomplicated acute renal failure , such as that due to simple hemorrhage mortality is low even when renal replacement therapy is required In acute renal failure complicated by series of infection and failure of multiple organ mortality is 50-70% Outcome is determined by the severity of underlining disorder and by complication rather than by renal failure itself.