Acute Kidney Injury + Fluid Balance Flashcards
how much fluid is in the intravascular space?
interstitial?
intracellular?
3L
9L
30L
normal GFR is greater than
90ml/min
actions of angiotensin - 2
increase antidiuretic hormone
increase aldosterone
increase thirst
constrict the efferent arteriole
what is AKI
significant decrease in GFR (>50%) over a period of hours to days leading to electrolyte, fluid, and acid imbalaance with decreased urine output
how much urea is reabsorbed and why
50%
creates concentration gradient for reabsorption
how much creatinine is reabsorbed
0%
creatinine production is proportional to
muscle mass
amount of urine for oliguria vs anuria
oliguric = <400mL/24hours anuric = <100mL/24 hours
how much GFR is lost before creatinine begins to rise?
50%
what is pre-renal renal failure? what causes it?
due to decreased renal perfusion
shock (septic, anaphylactic, cardiogenic, hypovolemic)
or drugs (ACEI, NSAIDs)
can lead to ATN
how do ACEI and NSAIDs reduce GFR
Ang-II constricts the efferent arteriole
prostaglandins dilate the afferent arteriole
what is renal AKI
intrinsice damage done acutely to the kidney parenchyma eg. ATN
usually ischemia related or toxin related
managenent of acute tubular necrosis
dialysis to maintain removal of toxins etc
restore circulating volume in diuresis stages to prevent hypovolemia
sodium restriction, potassium restriction
remove nephrotoxic drugs
in suspected acute kidney injury, what does STOP stand for
Sepsis
Toxins
Obstruction
Parenchymal insult
investigations for AKI
URINALYSIS
renal tract ultrasound
ABGs (pH)
potassium
comparing pre-renal to ATN
in pre-renal you can usually still concentrate the urine and reabsorb sodium, will have higher osmolarity in pre-renal
at what levels is hyperkalaemia concerning
> 6.5
relationship between insulin and potassium levels
insulin causes potassium to be taken up into cells, causing hypokalaemia.
lack of insulin causes potassium efflux and hyperkalaemia
what is SIADH and what does it cause
syndrome of innapropriate antidiuretic hormone
increases water reabsorption.
resulting hypervolemia often causes dilutional hyponatremia
what is diabetes insipidus?
what are the 2 types
lack of ADH leading to polyuria, polydipsia
cranial (no release of ADH)
nephrogenic (ADH doesnt work)
common cause of nephrogenic diabetes insipidus
lithium toxicity in bipolar
extracellular volume mirrors (sodium) content
sodium
how can we estimate intracellular volume
with sodium concentration
hyponatremia -> high intracellular volume
hypernatremia -> low intracellular volume
adding 3L isotonic saline will increase extracellular fluid or intracellular fluid?
extracellular
the concentration of sodium will be unchanged so intracellular will be unchanged
