CURRENT Essentials of Critical Care.pdf

Chapter 14 Renal Disorders 213■■■Renal Failure, AcuteEssentials of Diagnosis• Abrupt reduction in renal function resulting in azotemia• Reduced urine output but may be non-oliguric, anorexia, nausea,vomiting, hiccupping• Irritability, asterixis, headache, lethargy, confusion, uremic encephalopathy,coma• If pre-renal, orthostatic blood pressure and heart rate; if volumeoverloaded, jugular venous distension, gallops, rales• Pericardial rub, Kussmaul respirations may be seen• Hyperkalemia and acidosis can induce cardiac arrhythmias• Elevated blood urea nitrogen (BUN) and creatinine (Cr);BUN/Cr 20 in prerenal azotemia, some obstructive uropathy• Fe Na [(urine Na serum Cr)/(urine Cr serum Na)] 100;1% in prerenal azotemia; 1% in ATN• Urinalysis: pyuria, crystals, stones, hemoglobin, protein, casts,bacteriaDifferential Diagnosis• Prerenal azotemia: volume depletion, reduced cardiac output,hypotension, renovascular obstruction, NSAIDs, ACE inhibitors• Intrinsic renal failure: acute tubular necrosis (ATN), acuteglomerulonephritis, acute interstitial nephritis• Postrenal azotemia: prostate enlargement, tumor, blood clots,stones, crystals, retroperitoneal fibrosis• Hepatorenal syndromeTreatment• Fluid challenge should be considered• Avoid nephrotoxic agents: aminoglycosides, NSAIDs, contrast• Dietary restriction of sodium, potassium, phosphate, protein• Adjust dose of medications that are renally cleared• Renal ultrasound useful in evaluating for obstructive process;relieving obstruction essential once identified• Renal biopsy indicated if diagnosis elusive or when histologicaldiagnosis important for therapy• Dialysis for hyperkalemia, acidosis, fluid overload, uremicsymptoms, very catabolic patients (rapid sustained rise in BUN)■ PearlIn complete renal shutdown, the serum creatinine typically increasesby 1–2 mg/dL per day. When a more rapid rise is observed, rhabdomyolysisshould be considered.ReferenceAbernethy VE et al: Acute renal failure in the critically ill patient. Crit CareClin 2002;18:203. [PMID: 12053831]