Acute Kidney Injury Flashcards
What is acute kidney injury?
*a reduction in renal function following an insult to the kidneys.
What can the causes of AKI be divided into?
- Prerenal
- intrinsic
- post renal
What are the causes of prerenal AKI?
Major causes of AKI is ischaemia, or lack of blood flowing to the kidneys
Examples:
>hypovolaemia secondary to diarrhoea/vomiting
>renal artery stenosis
What are the causes of intrinsic AKI?
Relate to intrinsic damage to the glomeruli, renal tubules or interstitium of the kidneys themselves. may be due to toxins (drugs, contrast etc) or immune-mediated glomuleronephritis.
Examples:
- glomerulonephritis
- acute tubular necrosis (ATN)
- acute interstitial nephritis (AIN), respectively
- rhabdomyolysis
- tumour lysis syndrome
What are the causes of postrenal AKI?
Relates to problems after the kidneys. This is where there is an obstruction to the urine coming from the kidneys resulting in things ‘backing-up’ and affecting the normal renal function.
Examples:
- kidney stone in ureter or bladder
- benign prostatic hyperplasia
- external compression of the ureter
What are the risk factors for AKI?
- chronic kidney disease
- other organ failure/chronic disease e.g. heart failure, liver disease, diabetes mellitus
- history of acute kidney injury
- use of drugs with nephrotoxic potential
- use of iodinated contrast agent within past week
- Over 65
What are some examples of nephrotoxic drugs?
DAMN
- Diuretics
- ACEi/ARBs/Aminoglycosides
- Metformin
- NSAIDs
What is the definition of oliguira?
Less than 0.5ml/kg/hr
What can be given to reduce the risk of an AKI for at risk patients receiving contrast?
- IV fluids given before hand to reduce the risk
* Can temp stop nephrotoxic drugs
What are the key ways to detect a AKI?
- Reduced urine output <0.5ml/kg/hr
- Rise in molecules that the kidney usually excretes i.e. K+, urea and creatinine
- Fluid overload
What is the presentation of a patient in AKI?
- reduced urine output
- pulmonary and peripheral oedema
- arrhythmias (secondary to changes in potassium and acid-base balance)
- features of uraemia (for example, pericarditis or encephalopathy)
What does U&Es return that are important in assessing kidney function?
- Urea
- K+
- Na+
- Creatinine
What are the NICE definition of an AKI?
- a rise in serum creatinine of 26 micromol/litre or greater within 48 hours
- a 50% or greater rise in serum creatinine known or presumed to have occurred within the past 7 days
- a fall in urine output to less than 0.5 ml/kg/hour for more than 6 hours in adults and more than
What investigations should be completed in a patient with AKI? i.e. already had U&Es done
- 1st: Urinalysis
- If patient has no identifiable cause for deterioration or at risk of urinary tract obstruction they should have a renal USS within 24hrs
What is the management of AKI?
Supportive STOP AKI
*Sepsis screen
- Toxins review (stop nephrotoxic drugs and drugs that increase in toxicity i.e. lithium, metformin and digoxin)
- Optimise BP: fluids
*Prevent further harm >find underlying cause and treat >treat complications (hyperkalaemia) >review meds >review fluids
