AKI Flashcards
(28 cards)
Define oliguria and anuria
Oliguria - little urine <400ml/day
Anuria < 100ml/day
Define AKI. What is it measured in?
Acute Kidney Injury is a syndrome of decreased renal function (decline in actual GFR) that occurs over hours/days <2 weeks. Measured in serum creatinine or urine output decline.
Increase in SCr > 26.5umol/L in 48 hrs
Increase in serum creating by 1.5 x baseline within 7 days
Urine volume <0.5ml/kg/hr for 6 hours
What is the first stage of AKI?
SCr > 26.5umol/L or 1.5-2 times the baseline
URine output < 0.5ml/kg/hr for 6-12h
What is the 2nd stage of AKI
SCr > 2-2.9 x baseline
Urine output <0.5ml/kg/hr for >12h
What is the 3rd stage of AKI
SCr >354umol/L or 3 x baseline or initiated on RRT
<0.3ml/kg/hr for > 24h or anuria for 12h
What are the limitations of using serum creatining
Increased muscle mass - increased serum creatinine
Risk factors for AKI
Pre-existing CKD Age Male sex Comorbidity CVS disease Malignancy Chronic liver disease Complex surgery
Causal categories of AKI
Pre-renal (reduced perfusion to the kidney)
Renal (intrinsic damage to kidneys)
Post-renal (obstruction to the urine)
Describe pre-renal AKI
Decreased renal perfusion
If BP falls below a threshold the kidney is able to maintain blood flow and GFR declines.
reversible if recognised quickly
Give causes of pre-renal kidney failure
Hyppovolaemia - haemorrhage, diarrhoea and vomitting, burns, pancreatitis
Systemic vasodilation - sepsis, cirrhosis, drugs, anaphylaxis
Reduced CO - LV dysfunction, MI, cariogenic shock, tamponade
Renal preglomerular vasoconstriction - sepsis, hepatorenal syndrome, hypercalcaemia, drugs - NSAIDs
Postglomerular vasodilation - ACE inhibitors, ATII antagonists
What happens if pre-renal AKI is not treated promptly?
Kidney cells become hypoxic
Acute tubular necrosis occurs.
What is acute tubular necrosis?
Damage to tubular cells so that they cannot reabsorb water and salt efficiently.
It is caused by ischaemia - fall in renal perfusion
Nephroxins - damage toe epithelial cells - cell death and shedding, all drugs are potentially nephrotoxins
sepsis
Give the possible causes of renal AKI
Golmerular:
Acute glomerulonephritis - immune disease affecting the glomerulus
Acute tubular necrosis (prolonged pre-renal diseasE)
Acute tubule-interstitial nephritis - inflammation of the interstitial of the kidneys surrounding tubules:
Drug reaction - NSAIDs, antibiotics, PPIs
Infection - acute pyelonephritis
Vessels - vasculitis, DIC
Describe post-renal AKI and give causes.
Obstruction to urine flow after it has left the tubules.
This causes a rise in intratubular pressure, dilation of the renal pelvis and reduced renal function.
Obstruction at ureter, bladder, urethra
Where and how can post-renal AKI obstruction occur?
Within the lumen:
Renal stones, blood clot, stricture, tumour of renal tract
Within wall: (usually chronic)
Ureteric stricture, congenital
Pressure from external compression:
Pelvic malignancy, prostatic hypertrophy, aortic aneurism, retroperitoneal fibrosis
Give some exogenous and endogenous nephrotoxins
exogenous: NASAIDs, ATII antagonists, ACE-i
endogenous: myoglobin bilirubin
What is acute glomerulonephritis?
Immune disease of the glomerulus
primary - kidneys only
secondary - part of systemic response
What is acute tubulointerstital nephritis
Inflammation of the kidney interstitial due to infection or toxins
what sign indicates post-renal failure?
Anuria History of renal stones/prostatism/pelvic surgery Palpable bladder Pelvic masses Enlarged prostate
Describe the presentation in sepsis
Pyrexia and rigors (sudden feeling of cold or shivering) Vasodilation, warm peripheries Bounding pulse Rapid capillary erfill Hypotension
Describe the presentation of cardiac failure
Gallop rhythm Raised BP Raised JVP Pulmonary oedema (basal crackers and dyspnoea Peripheral oedema (sacrum ankle)
Give investigations to carry out in AKI, what are they to check for?
Serum biochemistry U&E - urea and creatinine
ECG - hyperkaleamia
Urine dipstick - protein, blood
Urine microscopy - different casts
Ultrasound Scan - kidney size/asummetry/stones
CXR -pulmonary oedema/ fluid overload/infection
LFT - hepatorenal sundrome
Immunological test for intrinsic renal disease
What serum biochemistry is expected and possible in AKI?
Raised urea and creatinine in all AKI
Hyperkalaemia, hyponatraemia, hypocalcaemia, hyperphosphataemia possible
ECG changes in hyperkalaemia
Tall T Small/absent P Increased P-R interval Wide QRS Asystole
