الفهرس 
PATHOPHSIIOLOGY OF ACUTE RENAL FAIILURE POSTCABGOnly 14 pages are availabe for public view
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Abstract
Acute renal failure (urine output <0.5 ml/kg/hr.)
following cardiopulmonary bypass is an uncommon but highly
lethal complication which arises in the setting of inadequate
cardiac function and may be associated with multi-organ
failure. Acute renal failure (ARF) after cardiopulmonary bypass
occurs in about 8% of adult cardiac surgical patients with some
preoperative renal impairment and in about 3-4%, of patients
with normal preoperative renal parameters.
A raised serum urea concentration (uremia) may
conveniently be classified as: Prerenal, renal, and postrenal.
Prerenal acute renal failure is characterized by diminished renal
blood flow (60 to 70 percent of cases). In intrinsic acute renal
failure, there is damage to the renal parenchyma (25 to 40
percent of cases). Postrenal acute renal failure occurs because
of urinary tract obstruction (5 to 10 percent of cases). The most
commonly encountered diagnoses are prerenal acute renal
failure and acute tubular necrosis (a type of intrinsic acute renal
failure).
The etiology of acute renal injury post CABG is thought
to be multifactorial. Ischemia-reperfusion, inflammation, and
atheroembolism are three common sources of renal injury.
Many risk factors are contributing in acute renal failure as advancing age, male sex, type and severity of of cardiac lesion,
preoperative renal dysfunction, preoperative dehydration and
excessive use of diuretics, effect premedication and induction
of Anaesthesia, effect of thoracotomy and effect of
cardiopulmonary bypass which include direct effect of bypass
on renal function, hemo-dilution, hypothermia, hemolysis,
vascular effects, osmolar and oncotic effect and microemboli.
To diagnose postoperative acute renal failure, we have to
look for it in the suspicious patients with the previously
mentioned predisposing and precipitating factors by the
following, History and physical examination of suspected
causes, Assess cardiac hemodynamics (filling pressures, cardiac
output), Monitor other electrolytes, blood glucose, and acidbase
balance frequently, Identify any drugs being prescribed
with adverse effects on renal function, Renal Imaging and
Laboratory studies which include: urine volume and
composition, blood urea and serum creatinine and clearance
tests.