What is the management of Acute Kidney Injury (AKI) following a snakebite?

Management of Acute Kidney Injury Following Snakebite

Snakebite-associated AKI requires immediate antivenom administration, aggressive fluid resuscitation, close monitoring of renal function and electrolytes, and early initiation of renal replacement therapy when indicated, with recognition that long-term renal sequelae occur in a substantial proportion of survivors. 1, 2

Immediate First Aid and Transport

• Transport snakebite victims by EMS immediately to allow delivery of supportive care before hospital arrival, as most snakebites in North America involve pit vipers (>95%) causing tissue injury, bleeding, and potential systemic toxicity 3
• Remove rings and constricting jewelry from affected limbs to prevent constriction injury from progressive swelling 3
• Do NOT apply ice, tourniquets, suction devices, electric shock therapy, or pressure immobilization bandaging for North American snakebites, as these interventions are ineffective or harmful 3
• Minimize patient exertion during transport, as walking increases systemic venom absorption 3

Pathophysiology of Snakebite-Associated AKI

Snakebite causes AKI through multiple mechanisms 1:

• Ischemia from systemic bleeding, vascular leakage, and decreased renal blood flow
• Direct proteolytic degradation of glomerular basement membrane by snake venom metalloproteinases
• Thrombotic microangiopathy with microthrombi deposition in renal microvasculature 4
• Direct cytotoxic effects of venom on renal cells
• Rhabdomyolysis with myoglobin accumulation in renal tubules
• Disseminated intravascular coagulation 2, 5

Initial Hospital Assessment and Risk Stratification

Identify high-risk patients at presentation using the following independent risk factors for AKI 2:

• Viperidae family snakebites (OR: 9.65)
• White blood cell count >10,000 cells/μL (OR: 3.55)
• Overt disseminated intravascular coagulation (OR: 2.23)
• Serum creatine kinase >500 IU/L (OR: 4.06)
• Serum sodium <135 mmol/L (OR: 4.37) - indicates renal tubular dysfunction
• Microscopic hematuria (OR: 3.60)
• Duration from snakebite to antivenom ≥2 hours (OR: 3.73)

Obtain baseline laboratory studies immediately 6, 1:

• Serum creatinine, blood urea nitrogen, and electrolytes (sodium, potassium, bicarbonate)
• Complete blood count with differential
• Coagulation profile (PT, PTT, fibrinogen, D-dimer)
• Serum creatine kinase
• Urinalysis with microscopy for hematuria
• Blood type and cross-match

Antivenom Administration

Administer antivenom as soon as possible, ideally within 2 hours of envenomation, as delayed administration (≥2 hours) is independently associated with AKI development 2, 5

While antivenom remains the standard of care for snake envenoming, evidence specifically for preventing TMA-associated AKI is limited 4. However, early antivenom administration combined with supportive care provides promising results 5.

Fluid Management and Hemodynamic Support

Initiate aggressive fluid resuscitation with isotonic crystalloids rather than colloids for volume expansion 3, 6:

• Target euvolemia through careful clinical assessment and daily fluid balance monitoring 6
• Monitor for signs of hypovolemia: tachycardia (present in 86% of cases), systolic BP <120 mmHg (68% of cases), oliguria (60% of cases) 5
• Use vasoactive drugs if needed to improve microcirculation and maintain adequate perfusion 7

Monitor fluid status rigorously 7, 6:

• Record clinical examination and fluid balance daily
• Avoid fluid overload while maintaining adequate tissue perfusion
• Conservative fluid management for patients without tissue hypoperfusion

Monitoring and Laboratory Follow-up

Measure serum creatinine, urea, and electrolytes at least every 48 hours, or more frequently in high-risk patients 7, 6:

• Stage AKI severity using KDIGO criteria: increase in creatinine ≥0.3 mg/dL within 48 hours, or ≥1.5 times baseline within 7 days, or urine output <0.5 mL/kg/h for 6 hours 6
• Monitor for oliguria/anuria as clinical features of AKI 1
• Track blood pressure, as hypertension may develop 8

Discontinue all nephrotoxic medications unless absolutely essential 6:

• Hold diuretics when AKI is diagnosed 6
• Do NOT use dopamine, loop diuretics, N-acetylcysteine, or recombinant human insulin-like growth factor-1 for treatment of AKI, as these are ineffective 3, 6

Renal Replacement Therapy

Consider early initiation of RRT for severe AKI complications 3, 6:

• Indications include: severe hyperkalemia, metabolic acidosis, uremic complications, fluid overload refractory to medical management
• In snakebite-associated AKI, 49-60% of patients require dialysis 2, 5
• Continuous RRT (CRRT) is preferable in hemodynamically unstable patients 6
• Stage III AKI (78.6% of snakebite AKI cases) often requires dialysis 2

Anticipate RRT needs early in stage 2 AKI with rapidly progressive oliguria or anuria 3

Thrombotic Microangiopathy Management

Do NOT use therapeutic plasmapheresis (TPE) for snakebite-associated TMA, as there is no evidence for benefit regarding dialysis-free survival 4:

• TMA occurs in 5.4-15% of certain snake envenomings (Hypnale spp., Daboia russelii, Pseudechis spp.) 4
• AKI occurs in 94% of TMA cases 4
• Standard supportive care with antivenom remains the approach

Supportive Care Measures

Implement comprehensive supportive interventions 7:

• Deep vein thrombosis prophylaxis
• Stress ulcer prevention
• Appropriate glucose control
• Enteral nutrition when feasible
• Monitor for and manage complications: ARDS, bleeding disorders, acute respiratory distress syndrome 5

Long-Term Follow-up and Prognosis

All patients with snakebite-associated AKI require long-term nephrology follow-up 1, 8:

• 41% of dialysis-requiring AKI survivors show persistent renal involvement at mean 45-month follow-up 8
• 5% progress to end-stage renal disease 8
• 20% have GFR <45 mL/kg/min 8
• Monitor for chronic kidney disease development, proteinuria, and hypertension 8

Target high-risk patients for intensive follow-up 3:

• Those requiring temporary RRT during acute phase
• Patients with persisting renal dysfunction at hospital discharge
• Initial follow-up can be performed by primary care physicians with nephrology referral as needed 3

Prognosis

With early hospitalization, prompt antivenom administration, and adequate supportive care 5:

• Mortality ranges from 6-19% in severe cases 2, 5
• 86% of patients recover from acute phase 5
• However, long-term renal outcome is not benign, with significant percentage developing chronic renal damage 8