Renal

Question 1

Kidney functions

Answer 1

Fluid, pH, ion homeostasis

Waste removal- urea, uric acid, creatinine, meds, toxins

Endocrine- RAAS system, EPO, 1,25 D3–> active vitamin D, Prostaglandin production

Question 2

Hypovolemic urine production

Answer 2

SNS and angiotensin II–> vasoconstrictive decrease in GFR and increase in Na+ reabsorption

Aldosterone increases Na+ reabsorption

ADH increases H2O reabsorption

Question 3

Hypervolemic urine production

Answer 3

ANP increases GFR via vasodilation

Reduced SNS and angio II allow vasodilation and Na+ excretion

Increased cap hydrostatic pressure discourages Na reabsorption

Decreased aldosterone decreases Na reabsorption in the DCT and CD

No ADH leads to H2O being impermeable to the CD

Question 4

Normal renal autoregulation

Answer 4

about 80-200 mmHg

Question 5

Most anesthetic agents lead to

Answer 5

Decreased GFR, UO, RBF, and e-lyte excretion

All major kidney functions affected

Question 6

Surg/Anesthesia effect on ADH, Aldosterone, RAAS system

Answer 6

Increase in ADH–> decreased UO

Increase in Aldosterone from baroreceptors detecting volume depletion

Hypotension (under 80mmHg) leads to a release of renin and further renal vasoconstriction

Question 7

Prostaglandins have what effect on the renal system

Answer 7

Protective against renal ischemia

Ischemia, renal hypotension, stress, promote their production

Oppose action of angio II, SNS, ADH,

Avoid ketorolac in pts at risk for medullary ischemia

Question 8

Low dose dopamine is

Answer 8

voodoo medicine

Question 9

T4-T10 sympathectomy will

Answer 9

Decrease catecholamines, renin, and ADH

Need fluid boluses to maintain RBF and GFR

Question 10

Which gas can create compound A

Answer 10

Sevo

Maintain flows over 2L

Question 11

Which gases have negligible levels of free fluoride ion from metabolism

Answer 11

Iso and Des

Methoxy>Enflu=Sevo are the worst

No evidence Sevo cause injury though

Question 12

PPV

Answer 12

More PIP/PEEP, less RBF/GFR/UO

Hydration will largely overcome this

Question 13

Periop oliguria is defined as

Answer 13

< 0.5ml/kg/hr of UO (<30ml/hr as a general number)

Question 14

Pre-op eval

Answer 14

HTN?
DM, MI, CHF?
Meds
Dialysis- pre/post weight, how much fluid off, when was last, e-lyte status

Question 15

Renal function tests

Answer 15

GFR:
BUN (10-20mg/dl)
Plasma Cr (0.7-1.5mg/dl)
Cr clearance (110-150ml/min)

Tubular function:
Urine spec grav (1.003-1.03)
Urine osmo (38-140mOsm/L)

Question 16

BUN

Answer 16

Inverse to GFR, >50 is indicative of decrease GFR
Not as sensitive as Cr
Can be abnormal, but GFR ok due to- high protein diet, GI bleed, fever, dehydration

Question 17

Plasma Cr

Answer 17

8-17 hour lag after a GFR change

Suggestive of ARF
50% increase indicates 50% decrease in GFR

Question 18

Cr clearance

Answer 18

Index of GRF
Most reliable ESTIMATE of GFR (don’t forget about Inulin aka gold standard for calculating GFR)

less than 25ml/min indicates moderate disease, less than 10 needs dialysis

Disadvantage- needs 2-24hr urine collection

Question 19

Chronic RF Hgb hovers around

Answer 19

5-8g/dl

Question 20

PT, PTT, bleeding time in CRF, reason and Tx

Answer 20

increased bleeding despite normal PT, PTT, and BT- cause is defective vWF

Give DDAVP 0.3-0.4mg/Kg over 30 minutes or cryo, also have blood warmer ready to go

Question 21

Hyperkalemia common, what EKG changes does it produce

Answer 21

Peaked T, long PR, long QRS, ST depression

HB and V-fib can result

Question 22

HyperMg leads to

Answer 22

CNS depression and coma

Question 23

high or low pH in CRF

Answer 23

low, can’t excrete H+ ions

Question 24

CXR for

Answer 24

HTN CV disease, pericardial effusion, uremic pneumonitis

Question 25

Dig tox EKG

Answer 25

Short QT, ST depression

Question 26

Hypocalcemia EKG

Answer 26

Long QT

Question 27

RF and drugs

Answer 27

Anemia, low serum protein, e-lyte changes, fluid retention, changed cell membrane dynamics all affect drugs

Drugs excreted by the kidney unchanged are CONTRAINDICATED, like gallamine, phenobarbital

Question 28

Common anesthetic drugs to use with caution in RF

Answer 28

Thiopental- high PB
Midazolam- 60-80% renal clearance, high PB
Dexmedetomidine- high PB

Question 29

Opioid of choice in RF

Answer 29

Fentanyl

Remi also ok

Question 30

Bad opioids in RF

Answer 30

Meperidine, morphine, hydromorphone

Question 31

Muscle relaxants to avoid in RF

Answer 31

d-tubo, metocurine, gallamine, pancur, pipecur, doxacur

Vec, roc ok (30% renal), but may see longer effect

Question 32

Extra caution with succs because

Answer 32

K is released! Only use if K is normal, but probably want to avoid it