Acute Kidney Injury (AKI) Flashcards
Acute kidney disease is an abrupt decline in _____ f_____ (hours to days) characterised by increased serum ______ and ____ and decreased/increased urine output
kidney function
creatinine and urea
decreased urine output
In general terms, what causes the decline in kidney function?
Accumulation of usually excreted substances
In AKI, the serum creatinine increases by ___ umol/l within 48 hours
26 umol/litre
Another way (other than a 26 umol/l creatinine) to define AKI is if the creatinine levels have…
increased by 1.5 times from is baseline within a week
How can you define AKI based on urine output?
If urine output < 0.5 ml/kg/hour for at least 6 consecutive hours
What classification scale is used to score severity of AKI?
KDIGO (kidney Disease: Improving Global Outcomes)
3 stages
Which stage indicates most severe AKI?
Stage 3
3x increase in serum creatinine from baseline
lower likelihood of kidney recovery
Causes of AKI are p___, r___ or p_____
prerenal, renal or postrenal
What are is the common factor in prerenal causes of AKI?
Hypoperfusion (causing ischaemia, damaging the cells so impaired clearance of waste products)
What are some prerenal causes of AKI?
Decreased cardiac output, cardio shock, cardiorenal syndrome
Hypovolaemia secondary to D&V
Liver failure
Renal artery blockage or stenosis
Drugs (NSAIDS and ACE-i which decrease GFR)
IV contrast
Name the common factor of renal causes for AKI?
Nephron and parenchyma damage
What are some renal causes of AKI?
Glomerulonephritis
Acute tubular necrosis
Acute interstitial nephritis
Rhabdomyolysis (breakdown of striated muscle)
Tumour lysis syndrome
What do post-renal problems causing AKI have in common?
Obstruction to urine results in ‘backing-up’ and affecting normal renal function
What are some post-renal causes of AKI?
Kidney stone in ureter or bladder
Benign prostatic hyperplasia
External compression of the ureter
What are risk factors for AKI?
Chronic kidney disease
Other organ failure eg HF
History of AKI
Nephrotoxic drugs
Iodinated contrast agents
65+ y/o
What is oliguria?
urine output of less than 0.5 ml/kg/hour
What kinds of drugs have nephrotoxic potential?
NSAIDs
Aminoglycosides (broad-spec antibiotics)
ARBs
Diuretics
What are some symptoms of AKI?
Reduced urine output
Pulmonary oedema
Peripheral oedema
Arrhythmias (acid-base balance, potassium levels)
Pericarditis or encephalopathy from uraemia
What investigations are there for AKI?
U&E: particularly K+, H+, urea and creatinine
FBC and CRP (c-reactive protein): check for infection
Renal biopsy: confirms intrarenal cause
USS: confirms post renal cuase
All patients with suspected AKI should have…
urinalysis
How is AKI managed?
Careful fluid balance (diuretics for fluid overload)
Review medications
Treat met acidosis with sodium bicarbonate
Treatment for hyperkalaemia
Last resort = renal replacement therapy (eg haemodialysis)
What is treatment option for hyperkalaemia to stabilise the cardiac membrane?
IV calcium gluconate
What is a treatment option for hyperkalaemia by shifting potassium from extracellular to intracellular fluid compartment?
Insulin and dextrose infusion
or Nebulised salbutamol
Why treatment option for hyperkalaemia aids removal of potassium from the body?
Calcium resonium
or loop diuretics
or dialysis.
How can the ratio of urea:creatinine be used to tell whether the cause of the AKI is pre-renal, renal or postrenal?
U: Cr
> 100:1 = prerenal
<40:1 = renal
40-100:1 = postrenal
When is Haemodialysis used?
AFUK
Acidosis (pH is lower than 7.1)
Fluid overload (oedema)
Uraemia (symptomatic)
K+ >6.5 (or see hyperkalaemia changes to ECG)
What are the ECG changes in hyperkalaemia?
Flattened P wave
Wide QRS
Tall T wave
True or false: Ace-i causes dilation of the afferent arteriole?
False
ACE-inhibitors cause constriction of the afferent arteriole so decreases perfusion to the glomerulus
What are the top 3 causes of AKI?
Sepsis
Cardiogenic shock
Major surgery
What is a characteristic of acute tubular necrosis?
Muddy brown casts in urine (dead tubular cells)
