Diuretics Flashcards
what are the kidneys primary functions?
maintenance of fluid balance
maintenance of acid-base balance
excretion of metabolic wastes
what are the kidneys secondary functions?
erythropoietin
renin (secreted by juxtaglomerular cells)
calcitriol
what does juxta mean?
next to
what does erythropoietin do?
tells bone marrow to make more RBCs
what triggers erythropoietin?
body senses hypoxia
kidneys and heart feel like they are not getting enough RBCs
nephron info
functional unit of the kidney
we have about 1,000,000 in EACH kidney
each one is about 2 inches long
afferent means that blood _________ the glomerulus and efferent means that blood ___________ the glomerulus
approaches
exits
glomerulus info
rich in blood, surrounded by Bowmen’s capsule (membrane)
functional unit of nephron that filters the filtrate
the filtration rate is determined by how well the ___________ functions
glomerulus
what is the path that the filtrate takes through the nephron?
water and small molecules are filtered into Bowmans capsule
through the proximal convoluted tubule (PCT)
through the loop of henle
the distal convoluted tubule (DCT)
to the collecting duct
what are the 4 basic renal processes?
- filtration
- reabsorption (resorption)
- secretion
- excretion
what is the peritubular capillary?
the capillary around the nephron
what are the 4 classes and actions of diuretics?
- loop diuretics
- thiazide diuretics
- potassium-sparing diuretics
- osmotic diuretics
define preload
the amount of blood volume that fills the ventricles in the diastole (relaxation) phase of the cardiac cycle (aka filling pressure)
define afterload
the pressure the ventricles must work against to open the valves so blood can leave the ventricles (aka peripheral vascular resistance)
pushing OUT to lungs or aorta
↑afterload = ↑cadiac workload
what is preload influenced by?
hypervolemia
heart failure
regurgitation of cardiac valves
what is afterload influenced by?
hypertension
vasoconstriction
loop diuretics are also called?
water pill
what is the prototypical loop diuretic?
furosemide
where does furosemide act?
ascending loop of henle
what does furosemide do? resulting in…
blocks the reabsorption of Na (H2O) and Cl
dilates blood vessels
↓preload
↓afterload
↓BP
what are the indications for loop diuretics?
to manage hypertension (not 1st line)
↓edema r/t HF, liver, renal disease
what are the adverse effects of loop diuretics?
hypotension
Na, K, and other electrolyte depletion
possible hyperglycemia
what is the prototypical thiazide diuretic?
hydrochlorothiazide (HCTZ)
where does a thiazide diuretic work?
acts in DCT
what does a thiazide diuretic do? resulting in…
blocks reabsorption of Na, (H2O), CL, K
RELAXES arterioles (not dilate)
↓preload
↓afterload
↓BP
what are the indications for thiazide diuretics?
first line tx for HTN (used for HTN more than HF)
mild to moderate management of HTN
adjunct tx for HF, liver disease
what are the adverse effects of thiazide diuretics?
electrolyte imbalance
hypokalemia
possible hyperglycemia
how does relaxing arterioles help?
reduce vasoconstriction which improves blood flow and less friction/shearing = less cholesterol plaques coming free and clotting
aldosterone is secreted by the __________
adrenal gland
what does aldosterone act on?
acts on DCT and collecting ducts
what does aldosterone do?
↑reabsorption of Na, H2O resulting in ↑blood volume and ↑BP (keeps us “profusing”)
excretion of K (when Na retained)
where is the adrenal gland located
“hat” on top of the kidney
what is the prototypical potassium-sparing diuretic?
spironolactone
where does the potsssium-sparing diuretic act?
DCT and the collecting ducts
what does the drug spironolactone do?
it is an aldosterone-antagonist
it blocks the reabsorption of Na, H2O
retains K
what are the indications for potassium sparing diuretics?
management of HTN
edema r/t HF, liver, renal disease
counteract K loss caused by other diuretics
what are the adverse effects of potassium sparing diuretics?
hyperkalemia
orthostatic hypotension
hypovolemia
what is the prototypical osmotic diuretic?
mannitol
where does the osmotic diuretic work?
PCT and descending limb
how does mannitol work? and what are the results?
↑osmotic force (to draw fluid into the tubule)
inhibits H2O reabsorption
produces rapid diuresis (related to drug concentration)
what are the indications for an osmotic diuretic?
edema (very severe)
↑intracranial pressure
what are the adverse effects of an osmotic diuretic?
dehydration (strict I/O)
what are the effects of diuretics on geriatric patients?
take dose in am
can cause dizziness
orthostatic hypotension
↑risk dehydration
and constipation
↓ doses w/ other diuretics and HTN med
↑ F&E imbalances
potassium supplements are contraindicated for what type of diuretic?
potassium-sparing diuretics (spironolactone)
what are the general nursing implications for diuretics?
D= diet
I= I/O
U= unbalanced F&E
R= ready for dynamic changes
E= no evening doses
T= take in am
I= ↑orthostatic hypotension
C=consider age
what are the “dynamic changes” related to diuretics?
light-headedness
VS
heart and breath sounds (crackles)
cardiac rhythm
for hydration purposes what do we see if high or low?
BUN, electrolytes and creatinine will be elevated when H2O levels go down
