Imaging Studies:

• Imaging studies in ARF are most important in the emergent workup of suspected postrenal azotemia. Please refer to Urinary Obstruction for a complete discussion of available imaging studies for this cause of ARF.

• Chest radiography

• 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.

Other Tests:

• Electrocardiography: Obtain routine ECGs to look for manifestations of hyperkalemia and arrhythmias, such as atrial fibrillation, related to atheroemboli.

Procedures:

• 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

Prehospital Care: Stabilize acute life-threatening conditions and initiate supportive therapy.

Emergency Department Care: Treatment of ARF ideally should begin before the diagnosis of ARF is firmly established. A high index of suspicion often is necessary to diagnose early ARF. Significant decreases in GFR frequently occur before indirect measures of GFR reveal a problem. All seriously ill medical patients (eg, elderly patients, diabetic patients, hypovolemic patients) should have ARF included early in their differential diagnosis.

• Physicians can play a pivotal role in reversing many of the underlying causes and preventing further iatrogenic renal injury if ARF is recognized early. After providing an adequate airway and ventilation, focus on fluid management of the ARF patient.

• Fluid management

• Patients with ARF represent challenging fluid management problems.

• Hypovolemia potentiates and exacerbates all forms of ARF.

• Reversal of hypovolemia by rapid fluid infusion often is sufficient to treat many forms of ARF. However, rapid fluid infusion can result in life-threatening fluid overload in patients with ARF.

• Accurate determination of a patient's volume status is essential and may require invasive hemodynamic monitoring if physical examination and laboratory results do not lead to a definite conclusion.

• Urinary catheter placement

• Urinary obstruction often is an easily reversible cause of ARF.

• Placement of a urinary catheter early in the workup of a patient with ARF not only allows diagnosis and treatment of urethral and bladder outlet urinary obstruction, and allows for accurate measurement of urine output.

• If available, bedside ultrasonography can quickly identify a large and distended bladder.

• Routine use of urinary catheters should be tempered by consideration of their inherent risks of introducing infections.