Acute Renal Failure Flashcards
What is acute renal injury?
Encompasses mild damage that does not cause azotemia to severe damage associated with anuria
May be pre-, post-, or renal
Is acute renal injury reversible or irreversible?
Reversible
What is acute renal failure?
Decreased GFR leading to retention of nitrogenous wastes
What is the RIFLE criteria?
Allows the clinician to objectively and uniformly define AKI
R: Risk I: Injury F: Failure L: Loss E: End stage kidney disease
What is the RIFLE criteria based on?
Proportion of serum creatinine increases and urine output decreases
What is the issue with using the RIFLE criteria in vet med?
Good baseline references for creatinine may not have been established at presentation
What is the IRIS AKI subgrading based on?
Same thing as RIFLE, creatinine to urine output
What is pre renal AKI due to?
Anything that causes insufficient blood flow to the kidney
Hypoxia, ischemia, dehydration, hypovolemia, hypotension, decreased circulatory volume, anesthesia, hypoadrenocorticism, trauma, sx, shock, heatstrocke, hypoalbuminemia, hypoperfusion (NSAID tox)
What is pre-renal AKI characterised by?
Reduced fractional excretion of sodium
What are some renal etiologies for AKI?
- Prolonged hypoperfusion
- Prolonged obstruction
- Excessive vasoconstriction
- Thrombosis/DIC
- Transfusion reaction
- Infection
- Immune diseases
- Neoplasia
- Secondary to systemic disease
- Nephrotoxins
What are some post-renal etiologies for AKI?
Urine leakage or obstruction causing damage to collecting tubules
May result in urine leakage and uroabdomen
What are the four phases of acute renal failure?
Initial, extension, maintenance, and recovery
What are the characteristics of the initial phase of AKF?
- Usually little to no clinical signs
- Decrease in urine output or increase in creatinine
Is intervention necessary in the initial phase of ARF?
Yes
What are the characteristics of the extension phase of ARF?
Continued hypoxia and inflammation
What part of the nephron is particularly susceptible to toxins and ischemia?
Proximal tubule and loop of henle
What is the maintenance phase of ARF?
Lasts 1-3 weeks typically, urine is usually ultrafiltrate and may be decreased or increased volume
What is the recovery phase of ARF?
Characterized by polyuria and extreme los of sodium
How long may the recovery phase of ARF last?
Weeks to months depending on damage
What causes intra-renal vasoconstriction?
Imbalance between the vasoconstrictors (endothelin) and vasodilators (NO)
What is the consequence of intra-renal vasoconstriction?
Endothelial injury, decreased oxygen, ATP deficiency, mitochondrial damage, oxidant injury, intracellular acidosis and hypercalcemia
What are the causes of tubular dysfunction?
- Tubular obstruction from crystals or detached RTE cells
- Cytoskeletal injury with loss of polarity
- Loss of tight junctions between cells
- Cell necrosis
What are some risk factors for ARF?
Dehydration, hypovolemia, anesthesia, hypoxia, SIRS
How do you prevent ARF?
Aggressive treatment of shock and dehydration, avoid nephrotoxic drugs especially in compromised patients
What needs to be monitored closely in acute renal patients?
Dehydration status, blood volume and pressure, cardiac and urine output, GFR (direct if necessary)
What are some renoprotective drugs?
- Calcium channel blockers (prevent Ca influx)
- Selective DA-2 receptor agonists (vasodilation)
- Selective DA-1 receptor agonists (prevents vasoconstriction)
- Erythropoeitin analogues (protect against hypoxia)
Should fluids be given to accute renal patients?
Yes, always, helps correct electrolyte abnormalities as well as pressure and volume issues
Why should ECG be monitored in acute kidney patients?
To asses patient for electrolyte associated arrhythmias
Can pressors be given to acute renal patients?
Yes, if hypotension cannot be resolved with fluid therapy
How do you diagnose acute renal issues?
- Correction of underlying cause
- Detection of reduced urine output
- Urinalysis
- Azotemia
- Reduced fractional excretion of sodium
- Renal tubular biomarkers
What are the initial bolus doeses to correct shock in the dog and the cat?
Dog: 60-90 mL/kg
Feline: 45 mL/kg
Over 60 min in 15 min interval boluses