Acute Kidney Fracture Flashcards
What defines AKI?
The sudden deterioration of renal function over hours or days with one of the following
- Increase in serum creatinine by 26.5 micromols within 48 hours
- Increase in serum creatinine greater than 1.5 X baseline, known/presumed to have occurred in the past 7 days
- Urine volume <0.5 ml/kg/hr for 6 hours
* Need to measure urine and have pre and post-operative creatinine levels
What are common physiological features of an acute kidney injury?
- Decreased GFR
- rapid increase in urea and creatinine in serum
- decreased urine output
- usually complication of serious illness
What is the main problem in prerenal AKI? What are 4 main causes?
Decreased perfusion
- Hypovolemia
- Cardiac Failure: Valve dysfunction, reduced CO
- Systemic vasodilation: sepsis, cirrhosis, anaphylaxis
- Impaired renal autoregulation
What is meant by renal auto-regulation? What drugs could impair it?
Balancing preglomerular vasoconstriction with postglomerular vasodilation to get the right renal blood flow and GFR
Could be impaired by: NSAIDS, ACE inhibitors, angiotensin II agonists, cyclosporine
What does a post-renal AKI indicate?
Obstruction to urinary flow which can occur at the ureters, bladder or urethra
Where can post-renal obstructions be coming from?
- Within the lumen: stones, clots, papillary necrosis, tumours
- Within the wall: congenital, ureteric stricture
- Pressure from outside: prostatic hypertrophy, malignancy, diverticulitis, pancreas, etc
What are some typical features of a post-renal AKI?
- Nausea and lethargy
- Decreased urine output
- fluid overload: edema, orthopnea
- electrolyte abnormality
- acid-base disturbance
- platelet dysfunction - GIT bleeding
- enlarged bladder
What is the cause of intrinsic AKI? What are 3 examples:
Any direct injury to the kidney
- Acute glomerulonephritis
- Tubular damage
- Vascular damage
What are 3 things that could cause tubular damage?
- Ischemia
- Sepsis
- Nephrotoxins
What are 3 things that cause vascular damage (that could lead to an intrinsic renal AKI?)
- Vasculitis
- TTP/HUS
- Malignant hypertension
What is acute tubular necrosis?
Cause of intrinsic AKI:
Severe acute ischemia resulting in tubular necrosis, damage to the epithelial cells may be from nephrotoxins (endogenous or exogenous). ATN is much more likely if there are nephrotoxins AND reduced perfusion
Name 3 examples of nephrotoxins
- Aminoglycosides (Gentamicin): alters phospholipid metabolism and cause renal vasoconstriction
- Bacterial endotoxins
- Tumour lysis syndrome
How would you manage AKI?
- ABCDE assessment
- Check serum K+ level
- Fix patient’s volume status
- Antibiotics if there’s sepsis
- Take them off any nephrotoxic drugs
What could you do to correct a patient’s volume level?
Colloids, blood, physiological fluid, dextrose (although not for resuscitation) just helps fluid distribute across compartments and is good for rehydration
What examination and investigation should you do for post-renal AKI?
Examine for a palpable bladder
Investigate using an ultrasound to exclude obstruction and confirm kidney size
