Flashcards in Acute Kidney Injury + Fluid Balance Deck (29):
how much fluid is in the intravascular space?
normal GFR is greater than
actions of angiotensin - 2
increase antidiuretic hormone
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
creates concentration gradient for reabsorption
how much creatinine is reabsorbed
creatinine production is proportional to
amount of urine for oliguria vs anuria
oliguric = <400mL/24hours
anuric = <100mL/24 hours
how much GFR is lost before creatinine begins to rise?
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
investigations for AKI
renal tract ultrasound
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
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
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?
the concentration of sodium will be unchanged so intracellular will be unchanged
adding 3L of water to a patient will increase extracellular or intracellular fluid?
it will increase both
1/3 will say extracelllar
2/3 intracellular due to the dilutional hyponatremia
addition or loss of sodium rich fluid will affect which compartment (intra or extracellular)
addition or loss of water will affect which compartment (intra or extracellular)
2/3 from intracellular
1/3 from extracellular
why cant you correct chronic hyponatremia too quickly?
neurons make their own osmoles to maintain cell size. restoring sodium will cause the cells to shrink quickly. causes myelitis