Emergency Medicine Hub / Renal & Genitourinary • 3 min read • 3 sections

Acute Kidney Injury & Dialysis Emergencies

Comprehensive emergency diagnosis and protocolized resuscitation of acute kidney injury (AKI), end-stage renal disease (ESRD) crises, and hemodialysis complications. Covers urine indices (FeNa and FeUrea), drug-induced acute interstitial nephritis, the AEIOU criteria for emergent hemodialysis, and emergency arrest of bleeding dialysis arteriovenous (AV) fistulae.

Resuscitation Quick Actions • First 2 Minutes

High-Acuity

AEIOU Dialysis Criteria

Acidosis (pH < 7.10), Electrolytes (K > 6.5 with ECG changes), Ingestion (SLIME), Overload (refractory pulmonary edema), Uremia (pericarditis/encephalopathy)

FeUrea over FeNa

If patient received loop diuretics, FeNa is invalid; FeUrea < 35% confirms prerenal azotemia with intact tubular function

Fistula Exsanguination

Apply direct single-finger digital pressure directly over bleeding puncture site; if refractory, place a superficial figure-of-8 3-0 Prolene suture

Uremic Pericarditis

Pericardial rub in ESRD indicates uremic pericarditis; anticoagulation during dialysis is strictly contraindicated (causes hemorrhagic tamponade)

Dialysis Disequilibrium

Cerebral edema during/after rapid initial hemodialysis; treat acute herniation with 20% Mannitol (0.5-1 g/kg IV) or 3% Hypertonic Saline

Peritoneal Dialysis Peritonitis (PD Peritonitis)

Cloudy peritoneal effluent with dialysate WBC > 100/mcL with >50% polymorphonuclear cells; treat with intraperitoneal (IP) empiric antibiotics (Vancomycin + Cefepime/Gentamicin added to dialysate bag).

Bottom-Line Clinical Pearl

In patients with acute kidney injury, calculate Fractional Excretion of Urea (FeUrea < 35%) when diuretics have been administered, as loop diuretics render FeNa falsely elevated. The absolute indications for emergent hemodialysis follow the AEIOU mnemonic: refractory Acidosis, life-threatening hyperkalemia (Electrolytes), toxic Ingestions (SLIME), refractory pulmonary edema (Overload), and Uremic pericarditis/encephalopathy. Bleeding from an AV fistula is an exsanguinating emergency: apply single-finger targeted direct digital pressure or a figure-of-8 suture—never place clamps across the entire fistula.

1. AKI Differentiation: Prerenal vs. ATN vs. AIN vs. Postrenal

Acute Kidney Injury (defined by KDIGO as an increase in serum creatinine by >= 0.3 mg/dL within 48 hours, a 1.5-fold increase over baseline, or oliguria < 0.5 mL/kg/h for > 6 hours) is rapidly categorized into prerenal, intrinsic renal, or postrenal etiologies:

AKI Category	Etiologies & Mechanisms	Urinary Indices & Microscopy	Emergency Management
Prerenal Azotemia (55-60%)	Renal hypoperfusion without structural parenchymal damage: dehydration, hemorrhage, sepsis, CHF (cardiorenal), cirrhosis (hepatorenal), NSAIDs (afferent arteriolar vasoconstriction), ACE inhibitors (efferent vasodilation).	BUN/Creatinine Ratio > 20:1 - Urine Sodium < 20 mEq/L - FeNa < 1.0% (avid sodium retention) - FeUrea < 35% (preferred if patient took diuretics) - Urine Osmolality > 500 mOsm/kg - Microscopy: Normal or Hyaline Casts.	Restore renal perfusion: - Hypovolemia: Isotonic crystalloids (Lactated Ringer's 500-1000 mL boluses) - CHF: Diuresis + afterload reduction - Withhold nephrotoxic drugs (NSAIDs, ACE-I/ARBs).
Intrinsic: Acute Tubular Necrosis (ATN) (35-40%)	Direct tubular epithelial cell injury: 1. Ischemic: Prolonged prerenal hypoperfusion/shock 2. Nephrotoxic: IV iodinated contrast, aminoglycosides, vancomycin, amphotericin B, rhabdomyolysis (myoglobin), hemolysis (hemoglobin).	BUN/Creatinine Ratio 10-15:1 - Urine Sodium > 40 mEq/L - FeNa > 2.0% (tubular reabsorption lost) - FeUrea > 50% - Urine Osmolality < 350 mOsm/kg (isosthenuria) - Microscopy: Pathognomonic 'Muddy Brown' Granular Casts and renal tubular epithelial cell casts.	Remove offending nephrotoxins; maintain euvolemia; avoid diuretic 'forcing' of urine (does not improve GFR or mortality); dose-adjust all medications; monitor for hyperkalemia and acidosis.
Intrinsic: Acute Interstitial Nephritis (AIN)	Immune-mediated tubulointerstitial hypersensitivity: - Antibiotics: Penicillins, cephalosporins, sulfonamides, ciprofloxacin - Medications: Proton pump inhibitors (PPIs), NSAIDs, allopurinol - Infections: Legionella, EBV, CMV.	Classic Triad (Fever + Maculopapular Rash + Arthralgias) present in only 10%! - Pyuria with WBC Casts - Eosinophiluria (Hansel or Wright stain, poor specificity) - Mild proteinuria (< 1-2 g/day).	Discontinue offending drug immediately (renal function usually recovers over weeks). Consider systemic corticosteroid therapy (Prednisone 1 mg/kg/day PO) if renal failure is progressive.
Postrenal: Obstructive Uropathy (5-10%)	Bilateral urinary outflow obstruction (or unilateral in a solitary functioning kidney): Benign prostatic hyperplasia (BPH), prostate/cervical cancer, bilateral urolithiasis, retroperitoneal fibrosis, neurogenic bladder.	Urinary indices variable (early mimics prerenal, late mimics ATN). - Urinalysis: Normal or microhematuria - Bedside POCUS: Demonstrates moderate to severe hydronephrosis. - Bladder Scanner: Post-void residual (PVR) volume > 200–300 mL.	Immediate bladder decompression: - Place 16-18 Fr Foley catheter (or Coude catheter for enlarged prostate). - If urethral catheterization fails, place emergency percutaneous suprapubic catheter. - Monitor for Post-Obstructive Diuresis (> 200 mL/h for > 2 consecutive hours); replace 50% of hourly urine output with 0.45% normal saline.

2. Indications for Emergent Hemodialysis: The AEIOU Framework

In patients with severe acute kidney injury or chronic end-stage renal disease (ESRD) with missed dialysis sessions, immediate nephrology consultation for emergent hemodialysis is indicated upon meeting one or more AEIOU criteria:

Mnemonic Letter	Clinical Indication	Specific Thresholds & Triggers	Emergency Bridge Therapy Prior to Dialysis
A: Acidosis	Severe Metabolic Acidosis	Arterial pH < 7.10 to 7.15 refractory to medical therapy or accompanied by severe volume overload where sodium bicarbonate boluses are contraindicated.	Isotonic Sodium Bicarbonate infusion (150 mEq in 1 L D5W) if volume status allows; continuous renal replacement therapy (CRRT) in unstable shock.
E: Electrolytes	Refractory Hyperkalemia	Serum Potassium > 6.5 mEq/L or any level associated with electrocardiographic changes (peaked T waves, PR prolongation, wide QRS, sine wave) refractory to medical shifting.	1. 10% Calcium Gluconate (30 mL IV) or Calcium Chloride (10 mL IV via central line) 2. Regular Insulin 10 units IV + D50W 50 mL 3. Albuterol 10-20 mg nebulized 4. Sodium zirconium cyclosilicate (Lokelma) 10g PO.
I: Ingestion	Dialyzable Toxic Ingestions (SLIME)	Salicylates (Aspirin level > 90-100 mg/dL acute, or severe acidosis) Lithium (level > 4.0 mEq/L or > 2.5 with neurotoxicity) Isopropanol (refractory shock) Methanol (level > 50 mg/dL or severe osmolar gap/acidosis) Ethylene Glycol (level > 50 mg/dL or severe gap acidosis).	Initiate specific antidotes (Fomepizole for toxic alcohols; Sodium Bicarbonate for salicylates); summon hemodialysis team immediately.
O: Overload	Refractory Volume Overload/Pulmonary Edema	Fulminant acute pulmonary edema with severe hypoxemia refractory to high-dose loop diuretics (or in an anuric ESRD patient).	1. High-flow Non-Invasive Ventilation (CPAP/BiPAP at 10-15 cmH2O) 2. High-dose IV Nitroglycerin (bolus 400-800 mcg IV over 2 min, then infusion 50-200 mcg/min) to shift volume from lungs to venous reservoir.
U: Uremia	Uremic Organ Dysfunction	Uremic Pericarditis (pericardial friction rub, risk of fatal tamponade) Uremic Encephalopathy (asterixis, lethargy, confusion, seizures) Uremic Bleeding (platelet dysfunction due to circulating uremic toxins with abnormal bleeding time).	For uremic bleeding: Administer DDAVP (Desmopressin) 0.3 mcg/kg IV (stimulates release of von Willebrand factor and Factor VIII from endothelium, transiently normalizing hemostasis within 1 hour).

3. Arteriovenous Fistula & Graft Emergencies

Arteriovenous (AV) fistulas and synthetic prosthetic grafts are high-flow, high-pressure vascular circuits. Disruption or puncture complications present with rapid, catastrophic exsanguination:

Vascular Emergency	Clinical Presentation	Immediate Hemostatic Technique
Puncture Site Exsanguination	Pulsatile, arterial-pressure hemorrhage following needle decannulation, dialysis dislodgement, or spontaneous pseudoaneurysm rupture.	Targeted Digital Compression: 1. Apply continuous firm pressure with a single gloved finger directly over the bleeding skin puncture point (do NOT compress the entire fistula, which causes complete thrombosis of the circuit). 2. If direct pressure fails after 15 minutes: Place a superficial Figure-of-8 stitch using 3-0 or 4-0 non-absorbable monofilament suture (Prolene) through the skin edges only, avoiding the underlying vessel wall. 3. If exsanguination continues: Apply an arterial pneumatic tourniquet proximally on the upper arm as a temporizing measure, and transport immediately to the operating room with Vascular Surgery.
Thrombosis/Loss of Thrill	Absence of palpable continuous thrill and auscultated machinery bruit over the vascular access conduit. Pain or distal cool limb.	Do NOT attempt forceful manual compression or massage. Urgent Vascular Surgery or Interventional Radiology consultation for catheter-directed pharmacomechanical thrombectomy within 24-48 hours.
Vascular Steal Syndrome	Severe distal hand/finger ischemia, pain during dialysis, pallor, coldness, and diminished distal pulses due to high fistula shunting.	Urgent vascular surgery evaluation for DRIL (Distal Revascularization and Interval Ligation) procedure.

AV Fistula Hemorrhage & Uremic Pericarditis: Critical Safety Mandates

Exsanguinating hemorrhage from a ruptured dialysis AV fistula can cause fatal hemorrhagic shock within 5 minutes. Never apply circumferential pressure dressings, clamps, or broad elastic bandages across the extremity, which induces total graft thrombosis and fails to arrest arterial flow. Use single-point digital pressure directly on the defect or a figure-of-8 skin suture. In ESRD patients with chest pain, auscultation of a pericardial friction rub indicates Uremic Pericarditis—an absolute emergency requiring prompt hemodialysis. Anticoagulation with heparin during hemodialysis is strictly contraindicated in uremic pericarditis, as systemic anticoagulation causes massive hemorrhagic conversion and fatal cardiac tamponade.

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