Renal and Urology Flashcards
location of the kidneys
- posterior part of abdomen
- 12th thoracic to 3rd lumber
- right is lower than left
- perirenal fat and renal fascia
renal hilus
- renal artery and vein
- lymphatics
- nerves
- ureters
what is the functional unit of the kidney? how many?
- nephron
- 1.25 million/kidney
types of nephrons
- cortical = 70-80%
- juxtamedullary = 20-30%: concentrate urine
what is the cardiac output the kidney receives?
- 20-25%
- 1100-1200 mL per minute
blood flow through kidney
- renal artery
- lobar artery
- interlobar artery
- arcuate artery
- interlobular artery
- afferent arteriole
- glomerulus
- efferent arteriole: smaller, increases pressure
- peritubular capillaries
- vasa recta: loop of Henle
- interlobular vein
- arcuate vein
- interlobar vein
- lobar vein
- renal veins
renal blood flow equation
RBF = (MAP - VP) x VR
VP = venous pressure VR = vascular resistance
regulation of RBF: autoregulation
- blood flow remains normal despite changes in BP
- maintains RBF between 50 - 180 mmHg
regulation of RBF: neural regulation
- innervated by sympathetic nervous system
- can be overridden by autoregulation
3 ways kidneys regulate urine formation?
- filtration
- reabsorption
- secretion
what is the most important index of renal function?
GFR
juxtaglomerular complex
- regulates GFR
- macula densa: distal convoluted tubule lies between afferent and efferent arteriole
- afferent and efferent arterioles consist of juxtaglomerular cells which contain renin
- sensitive to osmolality
what do the juxtaglomerular cells secrete? when (3)?
-renin
- sympathetic stimulation
- decreased delivery of Na and Cl
- decreased afferent arteriole perfusion
6 nephron segments
- glomerular capillaries
- proximal convoluted tubule
- loop of henle
- distal renal tubule
- collecting duct
- juxtaglomerular apparatus
renal: maximum transport
- maximum reabsorption has occurred and excess filtered material is excreted
- carrier is saturated
reabsorption/secretion: proximal tubule
- Na: active transport, capillary Na/K pump
- water and other electrolytes: co-transport
- large amount of mitochondria to support movement
what increases reabsorption of sodium in the proximal tubule?
- angiotensin 2
- norepinephrine
reabsorption/secretion: loop of Henle
- solute and water reabsorption follows concentration and osmotic gradients
- in thick ascending limb reabsorption of Na and Cl in excess of water – all four sites of carrier protein must be occupied, Cl is rate limiter
- descending permeable to water, ascending permeable to urea
reabsorption/secretion: distal convoluted tubule
- sodium reabsorbed under aldosterone
- water reabsorbed only under ADH
- potassium secreted for sodium
reabsorption/secretion: collecting duct
- hydrogen secretion, bicarbonate reabsorption: acidifies urine
- sodium reabsorbed under aldosterone
- water reabsorption dependent on ADH
what percentage of filtrate is reabsorbed?
99%
renal hormones: aldosterone
- increase Na and water reabsorption
- acts in distal nephron
- regulated by potassium and RAAS
renal hormones: ADH
- acts on distal tubule and collecting ducts
- inhibited by stretch of atrial baroreceptors
- released due to high osmolarity, hypotension, hypovolemia, angiotensin 2
renal hormones: ANP
- released by atria in heart due to stretch
- causes increase in sodium excretion, urine flow, RBF, GFR
renal hormones: EPO
-people will kidney disease develop anemia
renal hormones: prostaglandins
- PGE2: vasodilator
- Thromboxane A2: contraction of vascular smooth muscle
- protective during hypotension and ischemia
renal hormones: Vitamin D
-cholecalciferol converted to 25-hydrocholecalciferol in kidneys and then 1,25-dihydroxycholecalciferol in liver
renal: sevoflurane
- when reacted with soda lime, may create compound A which causes renal tubular necrosis
- increased with high concentration, low flow rates, increased temperature, increased CO2
renal failure: pain medications to avoid
- morphine
- Demerol
what is the only true physiologic diuretic?
water
osmotic diuretics (4) types
- mannitol
- urea
- glycerin
- isosorbide
avoid osmotic diuretics in which patients?
heart failure
osmotic diuretics mechanism of action
-increases the osmolarity of tubular fluid and prevents reabsorption
carbonic anhydrase inhibitors mechanism of action
- limit secretion of H+ ions and increase the loss of bicarbonate
- forms alkaline urine
carbonic anhydrase inhibitors (1) type
-Diamox/acetazolamide
avoid carbonic anhydrase inhibitors in which patients?
-renal and liver failure
avoid what medication when taking loop diuretics?
-NSAIDS; inhibit prostaglandin synthesis
loop diuretics mechanism of action
- prevent chloride reabsorption
- increased prostaglandin production which promotes renal artery vasodilation
aldosterone antagonists mechanism of action
-inhibit aldosterone: prevent the reabsorption of Na and water
loop diuretic (4) types
- bumex
- Lasix
- torsemide
- ethacrynic acid
aldosterone antagonists (2) type
- spironolactone
- eplerenone (selective antagonists: fewer side effects)
potassium sparing diuretics (4) types
- spironolactone
- eplerenone
- triamterene
- amiloride
potassium sparing diuretics mechanism of action
-inhibit potassium and hydrogen ion secretion in distal tubule
thiazide diuretics types
—thiazide
thiazide diuretic mechanism of action
-inhibit reabsorption of sodium and chloride in the ascending loops of Henle and the proximal and distal tubules
xanthines potentiate which diuretic?
-carbonic anhydrase inhibitors
xanthines mechanism of action
- naturally occurring
- stimulate CNS and cardiac muscle, relax smooth muscle
- increased GFR and increased sodium/chloride secretion
symptoms of rhabdomyolysis seen under anesthesia (2) and lab tests
- peaked T-waves
- myoglobinuria
- elevated serum CK, K, creatinine
- hypocalcemia
- lactic acidosis
rhabdomyolysis treatment
- fluid (NS over LR)
- electrolyte corrections
fenoldopam
- dopamine receptor agonist
- protective for situations that may lead to impaired renal function
prevent of contrasted induced acute renal failure
- fluid
- no NSAIDS
- newer contrast agents (iodixanol>isovue)
all forms of anesthesia can depress renal function by?
30-40%
fluoride ion renal toxicity
- methoxyflurane
- interferes with transport of sodium and chloride, vasodilator, ADH inhibitor
fluoride ion renal toxicity: symptoms
- polyuria
- hypernatremia
- hyperosmolality
- increased BUN, creatinine
nonoliguric, oliguric, anuric volumes
nonoliguric >400
oliguric <400, <0.5 mL/kg
anuric <100
major causes of kidney tubular injury
- ischemia
- endogenous/exogenous toxins
- infections
most common cause of AKI?
-prolonged renal hypoperfusion
5 stages of CKD
1: kidney damage with normal GFR
2: GFR 60-89
3: GFR 30-59
4: GFR 15-29
5: GFR<15
anesthetic considerations with CKD
- anemia
- pruritic
- metabolic acidosis
- electrolyte disturbances
- coagulopathies
- HTN
- pulmonary congestion/edema
what is the most reliable tool for renal function?
-creatinine clearance test
creatinine clearance formula and normal number
GFR=(urine creatinine x urine volume) x serum creatinine
-normal 95-150 mL/min
fluid for CKD?
- use NS
- do not use LR because of high potassium
brachytherapy
- insertion of radioactive implant to treat cancer
- low EBL
extracorporeal shock wave therapy
- high energy shock waves sent through body to break up kidney stones
- synced to R waves of heart: caution for arrhythmias
