AKI Flashcards by Anouk Wijeratne

What is AKI?

Sudden rapid reduction in eGFR with/without oliguria/anuria

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What is oligouria?

Reduced urine ouptue

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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

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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

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What are 4 main complications of the kidney injury?

Fluid Overload
- Pulmonary/Peripheral Oedema
Uraemia
Metabolic acidosis
Hyperkalaemia

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What in the management for fluid overload?

IV furosemide
GTN infusion (vasodilation)
Haemodialysis if refractory

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What is the outcome of high urea?

Uraemic encephalitis (lethargy, confusion)
Uraemic pericarditis

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What is the management of uraemia?

Haemodialysis

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What are the symptoms of metabolic acidosis?

Confusion
Tachycardia
Kussmaul’s breathing (drive of CO2 to increase pH)
Nausea and vomiting

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What is the treatment for metabolic acidosis>

IV Sodium Bicarb

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What are the symptoms of hyerpkalaemia?

Can be asympto
Arrthymias
Muscle weakness
Cramps
Paraesthesia
Hypotension
Bradycardia
Cardiac arrest

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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

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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’

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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

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Why is inuslin used in hyperkalaemia?

Drives K into cells

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What is calcium gluconate given in hyperkalaemia?

Cardioprotective

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Why is glucose used in hyperkalaemia?

Avoid hypoglycaemia

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What investigations are done for AKI? (diagnose)

Fluid assessment
(Pitting oedema, JVP etc.)

ABG/VBG, Potassium & Bicarb

Bloods: U&Es, CRP,

US KUB

ECG

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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

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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

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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)