renal section Flashcards
what type of bio transformations is the kidney capable of
phase 1 and 2
lungs excrete _______ acids and kidneys excrete ________ acids
lungs: volatile
kidneys: non volatile
when is EPO released via the kidney
when theres inadequate O2 delivery to kidney (anemia, reduced intravascular volume, hypoxia)
what stimulates erythrocyte production
EPO stimulates stem cells in bone marrow
what effect does PGE1 and PGE2 have on renal arterioles
vasodilation
what effect does thromboxane A2 have on renal arterioles
constriction
role of calcitrol with kidneys
- stimulates absorption of calcium from food
- instructs kidneys to reduce calcium and phosphate excretion
- increase deposition of calcium into bone
increased PTH _____’s calcitrol
increases
kidneys can synthesize _______ from amino acids
glucose
the kidneys receive _____ of CO (________mL/min_
20-25% (1000-1250mL/min)
How much of blood is filtered at glomerulus
20%
how much blood is reabsorbed in peritubular capillaries
99%
renal blood flow equation =
(MAP - renal venous pressure) / renal vascular resistance
how does blood flow through the kidney?
renal arteries -> renal segmental artery -> interlobular artery -> articulate artery -> interlobular artery -> afferent arterioles -> glomerular capillary bed -> efferent arterioles -> peritubular capillaries (reabsorption and secretion) -> venues -> interlobular vein ->arcuate vein -> interloper vein -> renal segmental vein
renal autoregulation includes
myogenic mechanism
JG apparatus
tubuloglomerular feedback
RAAS
prostaglandins
ANS
SNS
lower chloride concentration in ultrafiltrate does what
triggers renin release to activate RAAS
role of A2 and increase in GFR
constricts efferent arterioles
go over RAAS pathway
angiotensin–>(renin) angiotensin 1–> (ACE) angiotensin 2
5 roles of angiotensin 2
vasoconstriction (peripheral vessels and efferent arteriole)
increased aldosterone release from adrenal gland
SNS activation
increased ADH release from posterior ptuitary
increased thirst
where is aldosterone produced
zona glomerulosa of adrenal gland
what does aldosterone stimulate in kidney
Na/K/ATPase in principal cells of distal tubules and collecting ducts. H2O reabsorption and K/H excretion occurs
what two electrolyte changes increase aldosterone release
increased K or decreased Na
what is addisons
adrenocortical insufficiency (destruction of all cortical zones)
what stimulates ADH release
increased osmolarity of ECF. increased sodium shrinks osmoreceptors in hypothalamus. initiates transport of ADH from hypothalamus to posterior pituitary.
increased BV via unloading of baroreceptors in carotid sinuses, transverse aortic arch, great veins, right atrium
how doe ADH restore BP
stimulates V1 (vasoconstriction, increase in IP3, DAG, Ca2+), increases SVR
stimulates V2 in collecting duct (increased cAMP), aquaporin 1 channels inserted into walls of collecting ducts, H2O reabsorption, decreased plasma osmolarity, increased urine osmolarity.
net result= expansion in plasma volume
where are prostaglandins produced
afferent arterioles
arachidonic acid is liberated from cell membrane in response to
ischemia, HoTN, NE, AT2
how does NSAIDs decrease RBF
inhibiting production of vasodilation prostaglandins
endotoxins release ________, which leads to renal vasoconstriction
leukotriene production
what does the myocardium release in response to distention
ANP and BNP
what is the role of natriuretic peptides
inhibit renin release (negative feedback for RAAS) vasodilation and decreased BP.
promotes Na/H2O excretion into collecting ducts
where are dopamine 1 receptors found
kidneys and splanchnic circulation
second messenger and function of DA1 receptors
cAMP (increased),
vasodilator, increase RBF, increases GFR, diuresis, Na excretion
where are dopamine 2 receptors found
present on presynaptic adrenergic nerve terminal
second messenger and function of DA2 receptors
cAMP (decreased),
function, decreases NE release
what is freely filtered at the glomerulus
water, electrolytes, glucose
what determines glomerular hydrostatic pressure
- arterial BP
- afferent arteriole resistance
- efferent arteriole resistance
reabsorption in kidneys
substance transferred from tubule to peritubular capillaries
secretion in the kidneys
substance transferred from peritubular capillaries to tubule
what is excretion in the kidneys
substance removed from body in urine
what is the proximal convoluted tubule responsible for
bulk reabsorption of solutes and water
-water follows Na here via osmosis
-K/Cl/HCO3- follow Na in direct proportion
-organic bases, acids, and hydrogen ions are secreted into proximal tubule via Na counter transport mechanism
what percent of ions are absorbed in proximal tubule
65%
what is the primary role of the descending loop of henle
countercurrent mechanisms and high permeability to H2O
-primary function is to form concentrated or dilute urine.
-separates handling of Na/H2O
- theres an osmotic gradient, highly permeable to H2O and moderately permeable to ions
vasa recta
peritubular capillaries that run parallel to the loop of hence. returns reabsorbed water to the blood allowing osmolarity in peritubular insterstitium to remain high
what is the primary role of the ascending loop of henle
countercurrent mechanisms and no H2O permeability
- unlike descending LOH, thin and thick segments are not permeable to H2O
-ions pumped from tubular fluid into peritubular interstitium. Na/K/Cl co transporter is most important pump.
-since H2O cannot follow Na into peritubular interstitium, tubular fluid becomes more dilute and peritubular interstitium becomes concentrated
primary role of distal convoluted tubule
fine tune solute concentration
-Na(5%) is reabsorbed and Na/K/HCO3- follow via sodium co transport mechanism
-late distal tubule is impermeable to H2O except in the presence of aldosterone or ADH
-home to juxtaglomerular apparatus
-adjusts urea concentration
primary role of collecting duct
regulates final concentration of urine
-reabsorbs Na
-ADH and aldosterone also work in collecting duct
-ANP inhibits Na/H2O reabsorption
-adjusts hydration concentration
what is the function of carbonic anhydrase in the proximal tubule? (5 steps)
- CO2 and H2O diffuse into proximal convoluted tubule cells
- carbonic anhydrase facilitates production of H2CO3
- H2CO3 dissociates into H and HCO3-
- HCO3- diffuses into interstitium then blood
- H+ is returned to tubal lumen
carbonic anhydrase inhibitors noncompetitively inhibit
carbonic anhydrase in the cells that make up the proximal tubule.
what do carbonic anhydrase inhibitors reduce the reabsorption of?
HCO3, NA, H2O
examples of carbonic anhydrase inhibitors
acetazolamide 250-500mg
side effect and ultimate uses for carbonic anhydrase inhibitors
mild metabolic acidosis. used to treat high altitude sickness and central sleep apnea since it increases respiratory drive
what are osmotic diuretics (make up)
sugars that undergo filtration but not reabsorption
role of osmotic diuretics
inhibit water reabsorption in the proximal tubule (primary site). transiently increases plasma osmolarity
how loop diuretics exert their effect
disrupt the Na/K/2Cl transporter in the medullar region of the thick portion of the ascending loop of henle (primary site).
the amount of sodium that remains in the tubule overwhelms the distal tubules’ reabsorption capability so the patient eliminates large volumes of dilute urine
examples of loop diuretics
furosemide, bumetanide, ethacrynic acid
clinical uses of loop diuretics
acute pulmonary edema, AKI, CHF, increased Ca2+, HTN, anion DO, ICH, mobilization of edema fluid
key complication of loop diuretic
hypochloremic metabolic alkalosis
thiazides inhibit
Na/Cl co transporter in distal tubule. increases Ca reabsorption and serum calcium
SE of thazides
hyperglycemia, increased Ca, hyperuricemia (gout patients), hypokalemic hypochlorremic metabolic alkalosis, hypovolemia, HLD sexual dysfunction
meds that can increase risk of hyperkalemia
NSAIDS (decreases renin and atII mediated aldosterone release)
BB (suppression of aldosterone secretion at adrenal cortex and reduction in K uptake)
ACEI
tests and normal values of glomerular function include
BUN 10-20mg/dL
serum creatinine .7-1.5mg/dL
creatinine clearance 110-150mL/min
tests and normal values of tubular function (concentrating ability) include
fractional exertion of sodium 1-3%
urine osmolality 65-1400mOsm/L
urine sodium concentration 130-260mEq/day
urine specific gravity 1.003-1.030
100% increase in creatinine = ___________ in GFR
50% decrease
what is fractional exertion of sodium Fe(na)
relates to Na clearance to creatinine clearance.
if FeNa is less than 1%
more Na is conserved relative to the amount of creatinine cleared. this suggests pre renal axotemia
If FeNa is greater than 3%
more Na is excreted relative to the amount of creatinine cleared. suggests impaired tubular function
pre renal oliguria
FeNa
Urinary Na
urine osmolality
BUN:creatinine ratio
sediment
FeNa <1
Urinary Na <20
urine osmolality >500
BUN:creatinine ratio >20:1
sediment: normal, possible hyaline cysts
acute tubular necrosis
FeNa
Urinary Na
urine osmolality
BUN:creatinine ratio
sediment
FeNa >3%
Urinary Na >20
urine osmolality <400
BUN:creatinine ratio 10-20:1
sediment: tubular epithelial cells, granular casts
three systems used to classify AKI
- RIFLE (risk, injury, failure, loss, end stage)
- AKIN (acute kidney injury network)
- KDIGO: kidney disease improving global outcomes
causes of pre renal injury
hypo perfusion, decreased CO, systemic vasodilation, renal vasoconstriction, increased intra abdominal pressure
treatment of pre renal injury
IVF, hemodynamic support, PRBC’s, renal prostaglandins mediate vasodilation. avoid NSAIDS.
improvement in UOP after IVF confirms pre renal azotemia
causes of intra renal injury
ATN, ishemia, nephrotoxic drugs, parenchymal dysfunction
treatment of intra renal injury
restore renal perfusion, supportive
excessive use of .9% NaCl can cause
hyperchloremic metabolic acidosis
vasopressin constricts what in the kidney
efferent arteriole
do not use the following to prevent or treat AKI
low dose dopa, fenoldopam, ANP, recombinant human (Rh) IGF 1
avoid which abx
ahminoglycosides, amphotericin B (IV)
stages of chronic kidney disease (5)
- GFR >90
- GFR 60-89
- GFR 30-59
- GFR 15-29
- GFR < or = 15
s/sx of uremia
anemia, fatigue, n/v, anorexia, coagulopathy
1st line tx for uremia
desmopressin
2 ways CKD increases anemia
decreased production of EPO via kidneys, normochromic normocytic anemia
excess PTH replaces bone marrow with fibrotic tissue which increases anemia.
CKD shifts oxyhgb dissociation curve
to the right to help with metabolic acidosis
how does osteodystrophy happen in CKD
caused by decreased vitamin D production, secondary to hyperparathyroidism. PTH demineralizes bone to restore serum calcium conentration
5 indications for HD
- volume overload
- increased K (over 6)
- severe metabolic acidosis
- symptomatic uremia
- OD with a drug
FDA recommend that sevoflurane be administered at a rate of __L/min for no more than ___ MAC hours
1L/min for more than 2 MAC hours.
best nondepolarizing NMB’s for CKD
cisatracurium and atracurium
do you need an increased or decreased dosage of propofol in CKD patients?
increased related to hyper dynamic circulation and disruption of BBB secondary to azotemia
better opioid analgesics for CKD patients (that dont have metabolites that can accumulate) include
fentanyl, sufentanyl, alfentanil
radiographic contrast media causes nephrotoxicity by
ischemic injury due to vasoconstriction in renal medulla, direct cytotoxic effect
use what kind of contrast with CKD?
non ionic iso or low osmolar contrast instead of hyperosmolar
strategies to prevent injury from free myoglobin include
maintenance of RBF and tubular flow with IV hydration, osmotic diuresis with mannitol, keep UOP >100-150mL/h, administer NaHCO3 or acetazolamide to alkalinize the urine
two ways sevo can theoretically impair renal functoin
- compound A
- free fluoride ions
calcineuron inhibitors
are immunosuppressant agents that prevent the rejection of transplanted organs. sirolumus is a non cal
sirolumus
non calcineurin inhibitor that carries a much lower risk of nephrotoxity
most common approach to TURP (anesthetic)
spinal (T10 level necessary)
distilled H2O irrigation solution for TURP
osmolarity
pros
cons
0 mOsm/L
good surgical visibility
increases risk of TURP syndrome, hyponatramia, hemolysis, hemoglobinuria, renal failure
glycine irrigation solution for TURP
osmolarity
pros
cons
200 mOsm/L
decrease risk of TURP syndrome
increased ammonia, decreased LOC, transient post visual syndrome, blind/blurry vision for 24-48h, glycine is inhibitory transmitter in eye
sorbitol 3.3% irrigation solution for TURP
osmolarity
pros
cons
165 mOsm/L
decreased risk of TURP syndrome
increased BG, osmotic diuresis, lactic acidosis
mannitol 5% irrigation solution for TURP
osmolarity
pros
cons
275 mOsm/L
osmolarity similar to plasma, renal filtration and excretion (no metabolism)
cons: osmotic diuresis, transient plasma expansion
NaCl .9% irrigation solution for TURP
osmolarity
pros
cons
303 mOsm/L
osmolarity just a bit higher than plasma. absent of many SE’s associated with other solutons
cons: can only be used with bipolar electrocautery. do not use with monopoly.
presentation of TURP syndrome
triad: HTN, bradycardia, change in mental status
treatment of TURP syndrome
support with O2/CV. labs: lytes, HCT, creatinine, glucose
12 lead,
if Na >120 then restrict fluids and give furosemide
if <120 then give 3% NaCl at <100mL/h
bladder perf presentation and tx
abdominal and shoulder pain, decrease in irrigation fluid return
tx: supportive. serial H/H, emergent suprabupic cystotomy or even exlap
absolute contraindications to lithotripsy
pregnancy and risk of bleeding
relative contraindications to lithotripsy
Pacer/ICD. calcified aneurysm of aorta or renal artery, URI, obstruction, morbid obesity
anesthesia considerations for percutaneous lithotripsy
used when ESWL ineffective
stents placed
GETA and in prone
irrigation used
pneumothorax is a complicaton
anesthesia considerations for laser litho
breaks up stone, irrigation used, pts are usually in lithotomy.
how to calculate creatinine clearance (men)
(140- age) * (weight in kg) / (serum creatinine /72)
how to calculate creatinine clearance (men)
(140-age)* (kg) / (serum creat*72)
how to calculate creatinine clearance (women)
.85 (140-age)*(kg)/ (serum creat *72)
