Acute Kidney Injury Flashcards
What is the definition of acute kidney injury?
Increase in serum creatinine;
By > 26.5umol/L within 48 hours or
To > 1.5 times baseline which is known/presumed to have occurred within the prior 7 days
Urine volume < 0.5ml/kg/hr for 6 hours
What is the serum creatinine levels for AKI stage 1, 2 & 3?
AKI 1; 1.5-1.9 times baseline or > 26.5umol/L increase
AKI 2; 2-2.9 times baseline
AKI 3; 3 times baseline or increase to > 354umol/l or need for replacement therapy
What are the urine output criteria or stages 1, 2 and 3 AKI?
AKI 1; < 0.5ml/k/hr for 6 hours
AKI 2; < 0.5ml/kg/hr for 12 hours
AKI 3; < 0.3ml/kg/hr for > 24 hours or anuria for > 12 hours
Whata re the consequences of AKI?
Acidosis Electrolyte disturbance Intoxication toxins Overload Uraemic complications
What is the mortality of someone who has AKI and requires dialysis?
45-75%
What are the pre renal causes of AKI?
Cardiac failure Haemorrhage Sepsis Vomiting and diarrhoea Arterial occlusion NSAIDs, ACE inhibitors
What are the renal (intrinsic) causes of AKI?
Acute tubular necrosis - ischaemia
Toxins i.e. aminoglycosides, NSAIDs, radiocontrast, snake venom, heavy metals, mushrooms, rhabdomylolysis
Acute interstitial nephritis - PPI’s
Acute glomerularnephritis
Myeloma
Intra renal vascular obstruction i.e. vasculitis, thrombotic microangiopathy
What are the post renal causes of AKI?
Calculus Clot Sloughed papilla Malignancy - intraluminal TCC or multiple myeloma Ureteric stricture Radiation fibrosis Prostate disease
What is the most common cause of hospital accquired AKI?
Administration of radio-iodine contrast - radiocontrast nephropathy (RCN)
What puts you at risk of AKI from radioiodine contast? (Causing radiocontrast nephropathy)
Diabetes Renovascular disease Impaired renal function Paraprotein High volume radiocontrast
Why is the kidney suscpetible to hypoperfusion?
The medulla only contains 10-15% of the renal blood flow
The medulla is therefore hypoxic but still metabolically active
Therefore even a slight decreased in blood flow will affect the function of the medulla as it is low in oxygenation anyway
What are the features of renal failure in myeloma?
Cast nephropathy (myeloma kidney) Light chain nephropathy Amyloidosis Hypercalcaemia Hyperuricaemia
What investigations would you carry out to determine the undelrying cause of AKI?
FBC U&E Bicarbonate LFT’s Bone Clotting screen Myeloma screen Blood gas Urine dipstix, PCR/ACR, Bence Jones protein ANCA, iG, c3, c4, dsDNA (vasculitis) USS kidney Renal biopsy
What are the risk factors for AKI?
Age > 75 yrs Previous AKI Heart failure Liver disease Chronic kidney disease Diabetes Vascular disease Cognitive impairement
What events put a patient at risk of AKI?
Hypotension
Hypovolaemia i.e. haemorrhage
Toxins i.e. NSAIDS, radiocontrast, aminoglycoside
Major surgery
Sepsis i.e. pnuemonia, cellulitis, UTI etc
