Kidney Flashcards
Controls extracellular fluid volume (Na+ and water are reabsorbed)
Aldosterone
Controls plasma osmolarity (water is reabsorbed, but Na+ is not)
ADH (vasopression)
What are the hormones produced in the kidney?
- erythropoietin
- calcitrol
- prostaglandins
What causes the kidney to release erythropoietin?
- inadequate O2 delivery to the kidney (anemia, reduced intravascular volume, hypoxia)
- severe kidney dz reduces EPO production and leads to chronic anemia
How is Calcitrol synthesized in the kidneys?
- calciferol is synthesized by injested vit D or light exposure
- in the liver calciferol is converted to 25 [OH] Vit D3 (inactive Vit D3)
- in the kidney (under control of the parathyroid hormone) 25 [OH] Vit D3 is converted to calcitrol (1, 25 [OH]2 Vit D3 (active form)
What are the 2 functions of calcitrol?
- stimulate intestine to absorb Ca+2 from food
- stimulate bone to store Ca+2
stimulate kidney to reabsorb Ca+2 and phosphate
What are the renal prostaglandin hormones and what do they do?
- PGE2 and PGI2 vasodilate renal arteries
- thromboxane A2 constricts the renal arteries
What is urine output related to?
- linearly r/t MAP > 50mmHg
- NOT autoregulated
What are the two most important processes that carry out autoregulation?
- myogenic mechanism
- tubuloglomerular
What are conditions that increase renin release?
- Dec. renal perfusion pressure (hemorrhage, PEEP,CHF, liver failure w/ascites, sepsis, diuresis)
- SNS activation - Beta 1 (circulating catecholamines, exogenous catecholamines)
- tubuloglomerular feedback (dec Na+ & Cl in distal tubule)
What is Conn’s disease?
- excess aldosterone production
- Na+ retention and K+ loss
What is the principle determinant of osmolarity?
Na+ concentration
What are the two mechanisms that control ADH release?
- increased osmolarity in the ECF
- decreased blood volume
ADH stimulates which receptor in the collecting ducts and does what to cAMP?
- V2 receptor
- increases cAMP
What receptor does ADH stimulate to cause vasoconstriction in the peripheral vasculature? (inc IP3, DAG, Ca+2)
- V1
- net result is inc SVR
GFR is how many mL/min or L/day?
- 125 mL/min
- 180 L/day
What is the glomerular filtration fraction?
- 20% of RBF is filtered by glomerulus
- 80% is delivered to peritubular capillaries
What determines GFR?
hydrostatic pressure across the glomerulus
What is freely filtered by the glomerulus?
water, electrolytes, and glucose
What are the 3 determinants of hydrostatic pressure across the glomerulus?
- arterial blood pressure
- afferent arteriole resistance
- efferent arteriole resistance
Where is the region of the nephron where the MOST of the filtered Na+ is reabsorbed?
- Proximal tubule 65%
- Loop of Henle (thick ascending) 20%
- Distal tubule 5%
- Collecting duct 5%
- Urine 5%
What is reabsorbed in the proximal tubule?
- potassium
- chloride
- bicarb
- sodium
- water
What is secreted into the proximal tubule?
- organic bases and acids (bile salts, uric acid, catecholamines, toxins)
- H+ ions
What is reabsorbed in the Loop of Henle (descending)?
- water (20%)
What is reabsorbed in the Loop of Henle (ascending)?
- Na+ (20%)
- potassium
- chloride
- region is impermeable to water
- Hydrogen is EXCRETED via sodium countercurrent mechanism
What is reabsorbed in the Distal Tuble?
- Na+
- potassium, chloride, and bicarb (via sodium co-transport mechanism)
- late distal tubule is impermeable to water except in presence of aldosterone or ADH
- parathyroid hormone inc’s Ca+ reabsorption
What is reabsorbed in the Collecting Duct?
- Sodium (5%)
- ADH inc’s water reabsorption only
- Atrial natriuretic peptide inhibits water & Na+ reabsorption
- aldosterone works here
- adjusts H+ concentration
What is the most useful indicator of GFR?
- creatinine clearance
What is the most common cause of perioperative kidney injury?
ischemia-reperfusion injury
What is the standard monitor for urine production?
foley catheter
What medication should you avoid in pts at risk for kidney injury?
- NSAIDS
- NSAIDs dec. prostaglandin synthesis causing constriction of renal vasculature
What is the most common and second most common cause of CKD?
- DM
- HTN
What is the most common cause of death in CDK pts?
CAD
What are the 5 indications for use of dialysis?
- volume overload
- hyperkalemia
- severe metabolic acidosis
- symptomatic uremia
- overdose w/drug that is cleared by dialysis
What are anesthetic options for dialysis graft placement?
- brachial plexus block
- local infiltration
- general
What is the leading cause of death in dialysis pts?
infection
What are the best opioids to give a pt with renal failure?
- fentanyl
- sufentanil
- alfentanil
- remifentanil
What is the estimated absorbed volume while doing a TURP?
- 10-30 mL/min of resection time
What is the classic triad of TURP Syndrome?
- HTN (w/ inc. pulse pressure)
- Bradycardia (reflex)
- Change in mental status
How to estimate bleeding during TRUP?
2-5 mL of resection time
What are absolute contraindications to Extracorporeal Shock Wave Lithotripsy?
- Pregnancy
- risk of bleeding (bleeding disorder or anticoagulation)
