Acute Kidney Injury* Flashcards
What is an AKI
Abrupt decline in kidney function charecterised by high serum creatinine/urea and low urine output
What are the main 2 charecteristics of AKI
Raised serum creatinine (1.5x baseline or >26nmol/L for 2 days)
OR
Urine output <0.5/kg/hr for >6 hours
Low urine output (<0.5ml/kg/hr for >6hrs)
What is the classification system of AKI
KDIGO
What is the staging system of AKI
RIFLE
- Risk
- Injury
- Failure
- Loss
- End stage renal fail
What is the new preffered classification of AKI
AKIN
- Stage 1/2/3
- the higher the stage the lower the mortality
What can the causes of AKI be distributed into
Pre renal (Hypoperfusion) Renal (Kidney damage) Post renal (Obstruction)
What are the pre renal causes of AKI (HYPOPERFUSION)
Nausea and vomiting = Hypovolemia
Low CO (CHF, Cardiogenic shock)
Liver fail (Hepatorenal syndrome)
Renal artery blockage/stenosis
Drugs (NSAIDs and ACEi) Decrease GFR
What are the renal causes of AKI (Nephron and Parenchymal damage)
Acute tubular necrosis
Toxins (sepsis)
Interstitial damage
Glomerular damage
Renal cell apoptosis by Gentamycin
What are the post renal causes of AKI (Obstruction)
Stones
BPH
Drugs (CCB and Anticholinegenic)
Catheter occlusion
Tumours
What is the pathognomonic sign of Acute tubular necrosis
Muddy brown casts in urine
-Dead Tubular cells
What are the RF of AKI
Age
Comorbidities
Hypovolemia
Nephrotoxic drugs (NSAIDs)
What is the pathology of AKI
Decreased blood filtration and urine output
More excretion products at the kidney = AKI
Accumululation of “excreted” substances in the kidney
What are the pathogenic Electrolytesof AKI that are usually excreted with urine
K = hyperkalemia Urea = hyperuremia Fluid = oedema H+ = acidosis
What are the presentations of AKI
Hyperkalemia -> Arrythmia Hyperuremia -> pruritis and uremic frost Oedema (Pulmonary and peripheral oedema and hypovolemic shock) Metabolic Acidosis Haematuria, Proteinuria, Oliguria and Anuria
What can severe hyperuremia cause
Encephalopathy
-HE related due to ammonia
Why are ACE inhibitors CI in AKI
Constrict the afferent kidney so greater interstitial pressure by increased substrates
Dcreased perfusion to the glomerulus
How may an ECG present in AKI
Tall T Petite P Wide QRS Prolonged PR Sinusoidal wave
How is AKI investigated
KDIGO = Establish cause (PRE/RENAL/POST) U+E = Check K/Urea/H+/Creatinine FBC/CRP = Infection Renal biopsy = confirm renal cause USS = confirm post renal cause
How can you confirm an intrerenal cause of AKI
KDIGO and check serum urea/creatinine and urea outpur
Renal Biopsy
How can Post Renal causes of AKI be confirmed
KDIGO
U+E
USS
USS
How can you manage an AKI
Treat complciations -Hyperkalemia? calcium gluconate (Cardiac protective) -Acidosis? Sodium bicarbonate -Oedema? Diuretics Treat the cause Renal replacemnet therapy (RRT)
What is Renal Replacemnet Therapy
Haemodialysis if AFUKed
- Acidosis (<7.1)
- Fluid Oedema
- Uremic symptoms
- K Raised
What are the uremic symptoms of AKI
Prurits Uremic frost Confusion (HE) Anurea Palpable bladder Oliguria
What is the best way to establish the type of cause for AKI
Pre = >100 U:C Renal = <40 U:C Post = 40-100 U:C
What drugs should be stopped in AKI
NSAIDs
Aminogylcasides - Gentamycin and amikacin
ACE-I
ARB
Diuretics
What drugs should be considered stopping in AKI to prevent worsening
Lithium
Digoxin
Metformin
What is the normal GFR levels
90-120mg/mol
What are the normal urine levels
2.1-8.5mmol/l
What are the signs of hypovolemia
Low urine output
Dry mucus membranes and thirst
Dizziness w/N+V
Hypotension
Tachycardia
How can heart fail cause AKI
Hypoperfusion due to afferent arteriole constriction
-low renal blood flow and low GFR
How can Haemorrhage cause AKI
Blood lost by haemorrhage - Hypotension
Hypoperfusion of kidney due to hypotension
Why should insulin be prescribed for hyperkalemia
Sodium proton pump activation
More sodium enters cells activating sodium potassium ATPase
Potassium influx into cells
What can be given in adjunct to insulin for cardio protection
Calcium Gluconate
