AKI Flashcards
What is AKI?
Sudden rapid reduction in eGFR with/without oliguria/anuria
What is oligouria?
Reduced urine ouptue
What criteria is used to diagnose AKI?
KDIGO Criteria
Serum Cr
- Baseline x1.5
- > 26 micromol/L (>0.3mg/dL) increase
Urine output
- <0.5mL/kg/h for 6-12 hours
What are the 3 stage of the KDIGO criteria?
Stage 1
Cr increase 1.5x-1.9x
or >26micromol/L
UO <0.5mL/kg/h for 6-12 hours
Stage 2
Cr increase 2x-2.9x
UO <0.5mL/kg/h for more than12 hours
Stage 3 Cr increase 3x or >354 micromol/L (>4mg/dL) UO <0.3mL/kg/h for 24 hours Anuria 12h
If conflicting go with most severe
What are 4 main complications of the kidney injury?
- Fluid Overload
- Pulmonary/Peripheral Oedema - Uraemia
- Metabolic acidosis
- Hyperkalaemia
What in the management for fluid overload?
IV furosemide
GTN infusion (vasodilation)
Haemodialysis if refractory
What is the outcome of high urea?
Uraemic encephalitis (lethargy, confusion) Uraemic pericarditis
What is the management of uraemia?
Haemodialysis
What are the symptoms of metabolic acidosis?
Confusion
Tachycardia
Kussmaul’s breathing (drive of CO2 to increase pH)
Nausea and vomiting
What is the treatment for metabolic acidosis>
IV Sodium Bicarb
What are the symptoms of hyerpkalaemia?
Can be asympto Arrthymias Muscle weakness Cramps Paraesthesia Hypotension Bradycardia Cardiac arrest
How is severity of hyperkalaemia assessed?
5.5-6 Mild
6.1-6.5 Moderate
>6.5 Severe OR any K with ECG changes or symptomatic
What are the ECG changes seen in hyperkalaemia? (increasing severity)
Peaked T waves Wide PR interval Wide QRS duration Loss of P wave Sinusoidal wave
’ Hyperkalaemia box’
What is the treatment for hyperkalaemia?
Cardiac monitoring
If ECG changes are seen:
Calcium gluconate 10% 30mls IV
10U of soluble insulin
50mls of 50% glucose
Adjunct:
Salbutamol
IV furosemide
IV sodium bicarb
Why is inuslin used in hyperkalaemia?
Drives K into cells
What is calcium gluconate given in hyperkalaemia?
Cardioprotective
Why is glucose used in hyperkalaemia?
Avoid hypoglycaemia
What investigations are done for AKI? (diagnose)
Fluid assessment
(Pitting oedema, JVP etc.)
ABG/VBG, Potassium & Bicarb
Bloods: U&Es, CRP,
US KUB
ECG
What investigations are done for AKI? (cause)
Bloods: FBC, LFTs, CK, Clotting
Hepatitis/HIC scree, Vasculitic screen, Myeloma screen, sepsis screen etc.
Thorough medications history
How is AKI managed?
ABCDE approach (medical emergency)
Stop Nephrotoxic drugs if IV you need to stop ASAP even before results are back
Find and treat cause
What are the three categories of AKI causes?
Pre-renal: Problems with blood supply
Renal: Problems with kidney tissue
Post-renal: Problems with urine outflow
What are the pre-renal causes of AKI?
Hypovolaemia - losing fluid
Low volume - low fluid to begin with
Vascular insult
What are some causes of hypovolaemia?
Acute haemorrhage GI losses Diuresis Burns Third-spacing (water inside cells move out - sepsis, acute pancreatitis)
What are some causes of a low circulating volume?
Heart Failure
AKI + HF = Cardiorenal syndrome
Liver Failure
AKI + LF = Hepatorenal syndrome
Why can liver failure cause AKI?
Few proteins reduces
Osmotic effect
What causes vascular insults/poor perfusion of kidneys?
ACEi/ARBs
NSAIDS
Contrast used for scans
Renal artery stenosis
What are the three categories of post-renal AKI?
Luminal
Mural
Extramurla
What causes luminal, post-renal AKI?
Stones
- Urethra
- Ureters
What causes mural, post-renal AKI?
Cancers of renal tract
Strictures
What causes extramural, post-renal AKI?
Abdominal/Pelvic cancers
BPH
What are the four categories of renal AKI?
Tubular
Interstitial
Vascular
Glomerular
What tubular issues cause AKI?
ATN (Acute Tubular necrosis)
1. Ischaemic
2. Toxic
(Endogenous or Exogenous)
What are some toxins that harm the tubules?
Myoglobin, Uric acid
Cisplatin, NSAIDS
What is the management of tubular AKI?
Reversible, recovery in 21 days (cell turnover)
What is acute interstitial necrosis?
Immune mediated damage of renal interstitium
Will present with signs of allergy e.g. rashes, fever
High eosinophil count
White cell casts on urinalysis
What are vascular causes of renal AKI?
Haemolytic Uraemic Syndrome
Thrombotic Thrombocytopenia Purpura
Both damage the renal capillaries leading to the formation of microthrombi
What is the cause of HUS?
Most common in children is secondary to EHEC infection (E. Coli strain)
Presents with bloody diarrhoea
Managed with ABs
What causes TTP?
ADAMTS 13 deficiency
(Enzyme responsible for vWF breakdown)
Associated with pregnancy/HIV
What is the treatment of TTP?
Plasmapherisis to remove excess vWF
Rituximab
What are the two types of glomulonephritis?
Nephrotic - Non-proliferative
Nephritic - Proliferative
What are the features of nephrotic syndrome?
Non-proliferative
Massive protienuria >3.5g/d (foamy urine)
Hypoalbuminaemia <25g/L
Oedema
Hyperlipidaemia
Protein COAL (Proteinuria, cholesterol, oedema, albumin down, lipids up)
What are the features of nephritic syndrome?
Haematuria
Proteinuria
Oedema
BP increase
What are the 5 causes of nephrotic syndrome?
Minimal change disease Membranous GN FSGS Diabetic nephropathy Amyloid nephropathy
What is minimal change disease?
Common form of nephrotic syndrome in children
Idiopathic, associated with non-hodgkins lymphoma
Podocyte effacement on electron microscopy
Treated with corticosteroids - full recovery
What is membranous GN?
Common form of nephrotic syndrome in adults
Deposition of immune complexes on basement membrane
Diagnosis by exclusion:
BM thickening on light microscopy
Renal biopsy definitive
Conservative management e.g. low salt/protein diet, corticosteroids though low response
What are some RFs for membranous GN?
Autoimmune disease Hep B/C Syphilis Malignancy Medications (NSAIDS, gold, lithium)
What are symptoms of membranous GN?
asympto
oedema
xanthelasma
foamy urine
How is membranous GN diagnosed?
Light/Electron microscopy of renal biopsy
you can visualise basement membrane thickening
What is FSGS?
Focal segmental glomerulosclerosis
Caused by injury to podocytes
RFs: HIV, heroin
What is diabetic nephropathy?
Kidney damange caused by diabetes
Excess glucose eventually leads to BM thickening, matrix deposition which causes K-W nodules and glomerular damage
Microalbuminuria
Management: diabetic control, ACEi/ARBs to lower pressure
What is amyloid nephropathy?
Abnormal amyloid protein deposits
Tissue damage in kidneys
Congo red stain + polarising light will show apple green birefringence
What is the difference between nephritic and nephrotic syndrome?
Nephritic - hameaturia and some proteinuria
Nephrotoic - lots of proteinuria (frothy)
