What is the best course of treatment for a patient with acute renal failure, potentially with pre-existing conditions such as kidney disease, diabetes, hypertension, or heart disease?

Management of Acute Renal Failure

Patients with acute renal failure require immediate risk stratification based on severity and comorbidities, with nephrology consultation for those requiring renal replacement therapy, intensive monitoring of kidney function proportionate to disease severity, and aggressive avoidance of nephrotoxins while optimizing hemodynamics to prevent progression to chronic kidney disease and death. 1, 2

Immediate Assessment and Stabilization

Critical Laboratory Evaluation

• Check serum potassium immediately as patients with severe acute kidney injury are at extreme risk for life-threatening hyperkalemia (>6.5 mEq/L) 2
• Obtain ECG urgently to assess for hyperkalemic changes (peaked T waves, widened QRS, loss of P waves) 2
• Measure arterial blood gas or venous bicarbonate to evaluate for metabolic acidosis (pH <7.2 or bicarbonate <10 mEq/L indicates emergent dialysis need) 2
• Assess BUN:creatinine ratio to differentiate pre-renal azotemia from intrinsic renal disease 2

Volume Status Determination

• Examine for hypovolemia: orthostatic hypotension, dry mucous membranes, decreased skin turgor, tachycardia 2
• Assess for hypervolemia: peripheral edema, pulmonary edema, jugular venous distension 2
• In heart failure patients, calculate trans-kidney perfusion pressure (MAP - CVP) and target >60 mmHg 3
• Check for signs of hypoperfusion: altered mental status, cool extremities, narrow pulse pressure, elevated lactate 3

Risk Stratification and Follow-Up Intensity

High-Risk Patients Requiring Nephrology Referral

Patients with the following characteristics should receive nephrology follow-up if feasible: 1

• Pre-existing chronic kidney disease 1
• Congestive heart failure 1
• Diabetes mellitus 1, 4
• Cirrhosis 1
• Malignancy with or without chemotherapy 1
• Stage 2 or 3 acute kidney injury by KDIGO criteria 1
• Anuria persisting >24-48 hours despite volume optimization 2

Monitoring Frequency

• Severe acute kidney disease: Kidney function assessment within 3 days (no later than 7 days) after hospital discharge, followed by regular frequent assessments 1
• Moderate acute kidney disease: Evaluation at 3 months after acute kidney injury for resolution, new onset, or worsening of pre-existing chronic kidney disease 1
• Intensity of surveillance should be proportionate to risk of future chronic kidney disease progression 1

Renal Replacement Therapy Decisions

Indications for Emergent Dialysis

Initiate renal replacement therapy immediately for: 2

• Anuria persisting >24-48 hours despite optimization of volume status 2
• Hyperkalemia >6.5 mEq/L or any hyperkalemia with ECG changes 2
• Severe metabolic acidosis (pH <7.2 or bicarbonate <10 mEq/L) 2
• Severe uremic symptoms or complications 1
• Refractory fluid overload despite diuretic therapy 1, 3

RRT Modality Selection

• Continuous veno-venous hemofiltration (CVVH) or intermittent hemodialysis should be considered for severe renal dysfunction with anuria 2
• In heart failure patients with refractory oliguria, combine ultrafiltration or CVVH with inotropic support to increase renal blood flow and restore diuretic responsiveness 3
• For patients discharged on dialysis, use weekly assessment of serial pre-dialysis serum creatinine values and regular assessment of residual kidney function using 24-hour urine collection 1

Recovery Assessment

• Renal recovery is defined as sustained independence from RRT for minimum of 14 days 1
• Laboratory and clinical evaluation after cessation of acute RRT should occur within 3 days (no later than 7 days) after the last RRT session 1
• Avoid excessive fluid removal and hypotension during dialysis as these are critical factors that prevent re-injury and enhance likelihood of renal recovery 1
• Higher ultrafiltration rates and intradialytic hypotensive episodes are associated with higher risk of non-recovery 1

Hemodynamic Optimization

For Hypoperfused Patients

• Initiate intravenous inotropes (dobutamine or dopamine) immediately if signs of hypoperfusion are present to maintain systemic perfusion and preserve end-organ function 3
• Do not delay inotropic support when hypoperfusion signs are evident 3
• Support cardiac output, mean arterial pressure, and renal perfusion pressure to reduce acute renal failure risk 4

Fluid Management

• Fluid therapy is an effective prevention measure in certain clinical circumstances 4
• Avoid aggressive diuresis without confirming volume status 2
• In hypovolemic states, avoid diuretics as they worsen renal perfusion and function 2

Diuretic Strategy

When to Use Diuretics

• Start IV loop diuretics at doses equal to or exceeding chronic oral daily dose if patient is congested 3
• Monitor urine output hourly to titrate diuretic dose aggressively 3
• High-dose intravenous loop diuretics (>80mg furosemide) may be attempted as a trial in patients with evidence of fluid overload 2, 5

Critical Diuretic Pitfalls

• Do not withhold or reduce diuretics solely to preserve creatinine, as worsening congestion leads to worse outcomes 3
• Do not use diuretics as a substitute for renal replacement therapy in established acute kidney injury with anuria 2
• Avoid diuretics in hypovolemic states 2
• Furosemide combined with ACE inhibitors or angiotensin II receptor blockers may lead to severe hypotension and deterioration in renal function, including renal failure 5

Medication Management

Nephrotoxin Avoidance

Discontinue nephrotoxins when: 1

• Evaluation indicates the nephrotoxin is the potential cause of acute kidney injury 1
• A suitable and less nephrotoxic drug is available 1
• The nephrotoxin is considered non-essential 1

Avoid starting nephrotoxins when: 1

• Patient has known risk factors (advanced age, previous acute kidney injury, chronic kidney disease, diabetes, proteinuria, hypertension) 1
• Patient is already receiving a nephrotoxic drug with concern for drug interactions 1
• Concern exists for lack of appropriate follow-up of serum creatinine monitoring 1

Specific Drug Considerations

• Adjust renally excreted medications and withdraw drugs with active metabolites 1
• Nonionic, isoosmolar intravenous contrast should be used in high-risk patients 4
• ACE inhibitors and ARBs: The risk-benefit ratio in acute kidney disease may not reflect routine clinical practice; stopping during acute kidney injury periods and timing of restart is not well established 1
• Avoid concomitant use of furosemide with cisplatin (ototoxicity risk), NSAIDs (reduced natriuretic effect), cephalosporins (increased nephrotoxicity), and cyclosporine (increased gouty arthritis risk) 5

Monitoring Parameters

Essential Surveillance

• Monitor urine output, daily weights, serum electrolytes, BUN, creatinine, and fluid intake/output balance closely every 4-6 hours 3
• Regular monitoring of functional status while on nephrotoxins is needed 1
• Assessment of proteinuria is valuable for risk stratification in the post-acute kidney injury period 1

Vascular Access Considerations

• Avoid subclavian veins and internal jugular vein on the side of a future potential arteriovenous fistula for temporary acute vascular access 1

Advanced Therapy Evaluation

For patients with end-stage heart failure (ejection fraction 15%) and refractory acute renal failure, evaluate for mechanical circulatory support (LVAD), cardiac transplantation, continuous intravenous inotropic therapy, or hospice care if not a candidate for advanced therapies 3