AKI And CKD Flashcards
Difference between AKI and CKD
AKI- decrease in GFR which usually occurs within hours to weeks and is usually reversible
CKD is chronic kidney disease in which GFR is decreased over the course of over 6months, and is usually irreversible
Renal function is measured by…
Serum creatinine (U+E test)
Urination rate per hour
GFR (estimated through the serum creatinine value)
Causes of acute kidney injury AKI (pre, renal and post)
Pre renal AKI- caused by impaired perfusion (Shock)
Renal AKI- injury to the glmoeruli and tubules
Post renal AKI- caused by obstruction to urine excretion
Causes of shock
Hypovolemia
Sepsis = vasodilation=hypotension
Cardiac failure= ↓ blood output= ↓ perfusion
Embolis (obstruction to renal artery)
Body’s response to ↓ GFR and perfusion
Macula densa cells sense ↓ perfusion
JG apparatus
Renin release
Angiotensin II release with aldosterone = vasoconstriction and retention of sodium and water
Effect of the afferent arteriole and efferent arteriole in AKI
Vasodilation due to prostaglandins (afferent)
Vasoconstriction due to Ang II (efferent)
↑ resistance = ↑ pressure = ↑ GFR
Aldosterone effect on the kidneys
Causes the ↑ uptake of sodium ions in the DCT, causing ↑ water retention as a result which ↑ blood volume and rectifies any ↓ in BP
Features in prerenal AKI
↑ Na+ and water reabsorbtion
↑ urine osmolality
↑ urine specific gravity
↓ urine production
↓ fractional excretion of Na+
Renal AKI definition (ATN- acute tubular necrosis)
Inability of tubular cells to reabsorb/filter due to cell death, as a result of poor perfusion or toxicity
What causes poor perfusion in ATN acute tubular necrosis
Surgery
Hypotension
Sepsis= vasodilation = ↓ perfusion
What does ATN result in
↓ Na+ H2O reabsorption = ↓ volume of ECF
↓ urine osmolality
↑ urine output (damage to tubular cells = ↓ reabsorbtion of H2O)
↑ fractional Na+ excretion
Signs of Acute Tubular necrosis
↑ sodium in urine
↑ urine due to lack of reabsorption
Hyperkalemia (no swapping g with Na+)
Metabolic acidosis (H+ rentention and no secretion of HCO3- ions)
↓ GFR = fluid overload (oedema, pulmonary oedema)
Causes of renal toxicity
Radiocontrast dye
DAMN drugs
Myoglobin from muscles, which results from crush injuries
Post renal AKI definition
Obstruction to urinary excretion due to stones, ↑ prostate size or ureter tumour
Treatment of post renal AKI
Check for catheter
Add catheter if necessary, check the obstruction isn’t above this
Treat underlying cause, stones, prostate enlargement or tumour
Treat UTI/ Prevent