acute renal failure ppt

Acute renal failure what needs to be known:

DR P.M.SOHAL MD,DM(PGIMER CHANDIGARH) CONSULTANT NEPHROLOGIST LUDHIANA MEDICITI Acute renal failure what needs to be known

Acute Dialysis Quality Initiative (ADQI) group :

Acute Dialysis Quality Initiative (ADQI) group The RIFLE classification of ARF is as follows: Risk (R) - Increase in serum creatinine level X 1.5 or decrease in GFR by 25%, or UO Injury (I) - Increase in serum creatinine level X 2.0 or decrease in GFR by 50%, or UO Failure (F) - Increase in serum creatinine level X 3.0, decrease in GFR by 75%, or serum creatinine level > 4 mg/ dL ; UO Loss (L) - Persistent ARF, complete loss of kidney function > 4 wk End-stage kidney disease (E) - Loss of kidney function > 3 months

Frequency :

Frequency Annual incidence of community-acquired ARF is approximately 100 case per 1 million population. 1% of hospital admissions at presentation. Hospital-acquired ARF occurs in as many as 4% of hospital admissions and 20% of critical care admissions.

Mortality/Morbidity:

Mortality/Morbidity Community-acquired ARF are secondary to volume depletion, as many as 90% of cases are estimated to have a potentially reversible cause. Hospital-acquired ARF often occurs in an ICU setting and is commonly the end result of multiorgan failure. This dichotomy in the etiology of ARF explains the increased mortality rate, dialysis requirements, and rates of progression to end-stage renal failure seen in hospital-acquired ARF compared with community-acquired ARF. Mortality rates for ARF have changed little since the advent of dialysis at 50%. Currently, the mortality rate for hospital-acquired ARF is reported to be as high as 70% and is directly correlated to the severity of the patient's other disease processes. T The mortality rate among patients presenting to the ED with prerenal ARF may be as low as 7%. ARF is not a benign disease. In a recent study, a 31% mortality rate was noted in patients with ARF not requiring dialysis, compared with a mortality rate of only 8% in matched patients without ARF. Even after adjusting for comorbidity , the odds ratio for dying of ARF was 4.9 compared to patients without ARF. Mortality rates are generally lower for nonoliguric ARF (>400 mL /day) than for oliguric .S

Aetiology:

Aetiology Prerenal failure - Diseases that compromise renal perfusion Decreased effective arterial blood volume - Hypovolemia , CHF, liver failure, sepsis Renal arterial disease - Renal arterial stenosis (atherosclerotic, fibromuscular dysplasia), embolic disease (septic, cholesterol

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Intrinsic renal failure - Diseases of the renal parenchyma, specifically involving the renal tubules, glomeruli , interstitium ATN, ischemia, toxins ( eg , aminoglycosides , radiocontrast , heme pigments, cisplatin , myeloma light chains, ethylene glycol) Interstitial diseases - Acute interstitial nephritis, drug reactions, autoimmune diseases ( eg , systemic lupus erythematosus [SLE]), infiltrative disease ( sarcoidosis , lymphoma), infectious agents (Legionnaire disease, hantavirus) Acute glomerulonephritis Vascular diseases - Hypertensive crisis, polyarteritis nodosa , vasculitis

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Postrenal failure - Diseases causing urinary obstruction from the level of the renal tubules to the urethra Tubular obstruction from crystals ( eg , uric acid, calcium oxalate, acyclovir, sulfonamide , methotrexate , myeloma light chains) Ureteral obstruction - Retroperitoneal tumor , retroperitoneal fibrosis ( methysergide , propranolol , hydralazine ), urolithiasis , papillary necrosis Urethral obstruction - Benign prostatic hypertrophy; prostate, cervical, bladder, colorectal carcinoma; bladder hematoma; bladder stone; obstructed Foley catheter; neurogenic bladder; stricture

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Urinalysis: Microscopic examination of urine is essential in establishing differential diagnosis. Normal urinary sediment without hemoglobin , protein, cells, or casts generally consistent with prerenal and postrenal failure, HUS/thrombotic thrombocytopenic purpura (TTP), preglomerular vasculitis , or atheroembolism Granular casts - ATN, glomerulonephritis , interstitial nephritis RBC casts - Glomerulonephritis , malignant HTN WBC casts - Acute interstitial nephritis, pyelonephritis Eosinophiluria - Acute allergic interstitial nephritis, atheroembolism Crystalluria - Acyclovir, sulfonamides , methotrexate , ethylene glycol toxicity, radiocontrast agents

Value of serial Serum Creatinine:

Value of serial Serum Creatinine Serum creatinine is a reflection of creatinine clearance. Serum creatinine is a function of its production and excretion rates. Creatinine production is determined by muscle mass. Serum creatinine must always be interpreted with respect to patient's weight, age, and sex. The GFR can be estimated by the following formulas: The ADQI consensus committee on ARF favors the Modification of Diet in Renal Disease (MDRD) equation to estimate GFR (70 mL /min per 1.73 mm 2 is considered the lower limit of normal). Cockcroft- Gault equation: GFR mL /min = (140 - age y)(weight kg)(0.85 if female)/(72 X serum creatinine mol/L) MDRD equation: GFR, in mL /min per 1.73 mm 2 =   186.3 X ((serum creatinine ) exp[-1.154]) X (Age exp[-0.203]) X (0.742 if female) X (1.21 if African American)

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Complete blood count Leukocytosis is common in ARF. Leukopenia and thrombocytopenia suggest SLE or TTP. Anemia and rouleaux formation suggest multiple myeloma. Microangiopathic anemia suggests TTP or atheroemboli . Eosinophilia suggests allergic interstitial nephritis, polyarteritis nodosa , or atheroemboli . Coagulation disturbances indicate liver disease or hepatorenal syndrome.

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Blood chemistry Creatine phosphokinase (CPK) elevations are seen in rhabdomyolysis and myocardial infarction. Elevations in liver transaminases are seen in rapidly progressive liver failure and hepatorenal syndrome. Hypocalcemia (moderate) is common in ARF. Hyperkalemia is a common complication of ARF.

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Urine indices that suggest prerenal ARF include the following: Urine specific gravity >1.018 Urine osmolality ( mOsm /kg H 2 O) >500 Urine sodium ( mEq /L) <15-20 Plasma BUN/ creatinine ratio >20 Urine/plasma creatinine ratio >40

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Urine indices that suggest ATN include the following: Urine specific gravity <1.012 Urine osmolality ( mOsm /kg H 2 O) <500 Urine sodium ( mEq /L) >40 Plasma BUN/ creatinine ratio <10-15 Urine/plasma creatinine ratio <20

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Calculation of fractional excretion of sodium ( FeNa ) FeNa = (urine Na/plasma Na)/(urine creatinine /plasma creatinine ) FeNa FeNa >1% = ATN

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Advantages of FeNa compared to other indices Physiologic measure of sodium reabsorption Measured creatinine and sodium clearances, accounting for filtration and reabsorption of sodium FeNa increased before oliguric phase established and predictive of incipient ARF Exceptions (intrinsic renal failure with FeNa <1%) Urinary tract obstruction Acute glomerulonephritis Hepatorenal syndrome Radiologic contrast–induced ATN Myoglobinuric and hemoglobinuric ARF Renal allograft rejection Drug-related alterations in renal hemodynamics ( eg , captopril , NSAIDs)

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Imaging studies in ARF are most important in the emergent workup of suspected postrenal azotemia . Obtain chest radiographs on a routine basis to look for evidence of volume overload. Findings of lung infiltration can lead to pulmonary/renal syndromes, such as Wegener granulomatosis and Goodpasture syndrome, or evidence of pulmonary emboli from endocarditis or atheroembolic disease

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Renal biopsy Often helpful in finding specific cause of renal failure; however, not an ED procedure Reserved for evaluation of ARF when cause cannot be determined Especially important when glomerular causes of ARF are suspected Often helpful in finding specific cause of renal failure

TREATMENT:

TREATMENT Drug Category: Diuretics Patients with nonoliguric (rather than oliguric ) ARF have better mortality and renal recovery rates, prompting many to recommend diuretics in oliguric ARF. Unfortunately, randomized double-blind controlled trials fail to show benefit. Studies conclude that diuretics are useful only in management of fluid-overloaded patients. Drug Name Furosemide ( Lasix ) Description Increases excretion of water by interfering with chloride-binding cotransport system, which in turn inhibits sodium and chloride reabsorption in ascending loop of Henle and distal renal tubule. Also is potent vasodilator of medullary vessels, serving to wash out concentration gradient of countercurrent system, resulting in marked diuresis . Adult Dose 20-80 mg PO/IV once; ordinarily, prompt diuresis ensues; repeat 6-8 h later prn , or dose may be increased; increase dose by 20-40 mg no sooner than 6-8 h after previous dose until desired effect Pediatric Dose 2 mg/kg PO/IV, once; may increase by 1-2 mg/kg no sooner than 6-8 h after previous dose; not to exceed 6 mg/kg Contraindications Documented hypersensitivity; hepatic coma; anuria ; severe electrolyte depletion Interactions Metformin decreases concentrations; interferes with hypoglycemic effect of antidiabetic agents and antagonizes muscle-relaxing effect of tubocurarine ; concurrent aminoglycosides cause auditory toxicity—hearing loss of varying degrees may occur; may increase anticoagulant activity of warfarin ; increased plasma lithium levels and toxicity are possible Pregnancy C - Safety for use during pregnancy has not been established. Precautions Measure serum electrolytes, carbon dioxide, glucose, creatinine , uric acid, calcium, and BUN frequently during first few months of therapy and periodically thereafter; excessive diuresis may cause dehydration and blood volume reduction with circulatory collapse and possibly vascular thrombosis and embolism, particularly in elderly patients

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Drug Category: Vasodilators Renal vascular vasodilators in ARF make a great deal of sense from theoretical and experimental viewpoints. However, effective blood-volume restoration is the best physiologic vasodilator. Low-dose dopamine is a potent vasodilator, increasing RBF in ARF. Unfortunately, most clinical studies fail to show that it improves recovery or mortality rates. In the majority of ARF studies, dopamine was associated only with an increase in urine output. Current recommendations for dopamine favor its use in patients with ARF patients and CHF. Balance benefits of diuretic action with proarrhythmic side effects. Drug Name Dopamine ( Intropin ) Description Stimulates both adrenergic and dopaminergic receptors. Hemodynamic effect depends on dose; lower doses stimulate mainly dopaminergic receptors that produce renal and mesenteric vasodilation ; cardiac stimulation and renal vasodilation produced by higher doses. After initiating therapy, dose may be increased by 1-4 mcg/kg/min q10-30min until satisfactory response attained; maintenance doses Adult Dose Low renal dose: 1-5 mcg/kg/min IV Pediatric Dose Administer as in adults Contraindications Documented hypersensitivity; pheochromocytoma ; ventricular fibrillation Interactions Phenytoin , alpha- and beta-adrenergic blockers, general anesthesia , and MAOIs increase and prolong effects Pregnancy C - Safety for use during pregnancy has not been established. Precautions Closely monitor urine flow, cardiac output, pulmonary wedge pressure, and BP during infusion; prior to infusion, correct hypovolemia with either whole blood or plasma, as indicated; monitoring central venous pressure or left ventricular filling pressure may be helpful in detecting and treating hypovolemia

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Renal replacement therapy The principal methods of renal replacement therapy (RRT) are intermittent hemodialysis (IHD), continuous venovenous hemofiltration (CVVH), and peritoneal dialysis (PD). Each has advantages and limitations. IHD is widely available, has only moderate technical difficulty, and is the most efficient way of removing a volume or solute from the vascular compartment quickly. Unfortunately, dialysis-associated hypotension may adversely affect remaining renal function, particularly in patients who are critically ill. This is one reason CVVH is widely recommended in this setting

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Continuous RRT techniques are more expensive and not universally available; however, in addition to avoiding hypotension, they are believed to achieve better control of uremia and clearance of solute from the extravascular compartment. Because it continues around the clock, CVVH is able to remove larger fluid volumes, which is a significant advantage with critical care patients on parenteral nutrition and multiple infusions. CVVH may also preserve cerebral perfusion pressure more effectively. A theoretical though contested advantage of CVVH is the clearance of mediators of the inflammatory cascade. Although several studies have sought to directly compare CVVH to IHD, no study has shown a convincing advantage for one therapy over the other; in spite of this, many authorities assert that the choice of IHD over CVVH in the setting of shock would be inappropriate and unethical

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Peritoneal dialysis is inexpensive, widely available, and does not result in hypotension. However, it is not capable of removing large volumes of fluid or solute. Its use may be most common in children. Indications for and timing of initiation of RRT are also important and somewhat controversial subjects. Widely accepted indications for initiation of RRT include the following: Volume overload Hyperkalemia (K + >6.5 or rising) Acid-base imbalance Symptomatic uremia ( pericarditis , encephalopathy, bleeding dyscrasia , nausea, vomiting, pruritus ) Uremia (BUN>100) Dialyzable intoxications

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Severe dysnatremia ( 165), and dysthermia may also be appropriate indications for RRT. Significant intoxications with a dialyzable agent ( eg , methanol, ethylene glycol, theophylline , aspirin, lithium) may be the strongest indication for emergent dialysis because other effective therapeutic interventions are available for most of other complications of ARF. Volume overload can be treated with nitrates and phlebotomy; hyperkalemia can be treated with calcium, insulin, glucose, bicarbonate, binding resins, and beta agonists.

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The timing of initiation of RRT in the absence of the aforementioned indications is more controversial, although the consensus that RRT itself contributes to the resolution of ARF may be growing. Intensity of RRT is another area of active controversy and research; 2 recent studies suggest that more is better. In a study of CVVH intensity in which patients with ARF were randomly given standard or supernormal levels of ultrafiltration , the patients with more intense RRT had significantly lower mortality rates. A second randomized trial compared daily IHD with traditional every-other-day IHD in patients with ARF and found that the mortality rate (28% vs 46%) and speed of renal recovery (9 d vs 16 d) were significantly improved. However, before these studies, no significant evidence indicated that increased dialysis dosage improved outcomes.

Management of ATN:

Management of ATN Prevention:- Vigrous fluid replacement/ Mannitol and alkalinisation in cases of crush injuries. Saline (.9%) hydration/N acetyl cystein and or Fenoldapam to prevent Contrast induced nephropathy . Fluid/ alkalinization in Myloma cast nephropathy/ Tumour lysis syndrome. Low dose dopamine and Furesemide are of no proven value in prevention. However Furesemide may convert oliguric ARF to non oliguric renal failure making fluid management easier.

RECOMENDATIONS:

RECOMENDATIONS Modern practice is to initiate renal replacement therapy sooner rather than later, for example, when the plasma urea concentration reaches 25–30 mmol /l and the plasma creatinine concentration 500–700 μmol /l, perhaps even earlier, unless there is clear evidence that renal function is about to recover. A plasma urea concentration of greater than 45 mmol /l usually requires urgent institution of treatment. There are, however, no controlled trials relevant to modern practice that can be used to justify the initiation of renal replacement therapy at one specific plasma urea or creatinine concentration rather than another.

STATE OF ART H-D MACHINES:

STATE OF ART H-D MACHINES