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Perf Tech 3 > 2. Renal Response- Exam 1 > Flashcards

2. Renal Response- Exam 1 Flashcards

1
Q

What is the functional unit of the kidney

A

nephron- each kidney has more than 1 million

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2
Q

what are the 2 main parts of the nephron

A

glomerulus

tubular system

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3
Q

which part of the nephron allows filtration of fluid from plasma (no cellular components or proteins)

A

glomerulus

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4
Q

the glomerulus membrane is how much more permeable than normal capillaries?

A

100x

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5
Q

which part of the nephron collects filtered fluid and alters the composition- converting plasma filtrate to urine?

A

tubular system

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6
Q

describe the blood flow path through the glomerulus

A

afferent arteriole- to glomerulus- to efferent arteriole

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7
Q

what is the normal GFR for a normal adult

A

100-200 ml/min

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8
Q

is the GFR preserved over a broad range of pressures

A

yes

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9
Q

what % of volume filtered is reabsorbed (osmotic diffusion)

A

99%

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10
Q

with GFR- what is actively reabsorbed

A

glucose and amino acids

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11
Q

with urine output- there will be a linear increase in output with increase in what?

A

arterial blood pressure

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12
Q

an increase pressure of 100 to 200 mmHg will increase urine output by factor of ___?

A

7

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13
Q

a decrease in blood pressure below 50 mmHg will cause what?

A

urine output to stop

◦ allows long term control of blood pressure

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14
Q

Patients undergoing ____ surgery have ____ the risk of getting acute renal failure compared to ____ patients

A

Valve
Twice
CABG

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15
Q

What is the most significant risk factor for getting acute renal failure

A

Preoperative renal dysfunction

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16
Q

what are 2 signs of Preoperative renal dysfunction

A

Elevated serum creatinine

Decreased creatinine clearance

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17
Q

besides pre-op renal dysfunction- name 4 other risk factors for getting acute renal failure

A

impaired cardiac function
complexity of procedure
advanced age
genetics

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18
Q

what procedure has the highest % of dialysis

A

CAB / MVR

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19
Q

what procedure has the least % of dialysis

A

CABG

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20
Q

ARF-D develops in ____% of patients post CPB

A

1.2 to 13%

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21
Q

Name 8 intraoperative renal risk factos

A 
Low flow
Decreased blood volume
IABP
Prolonged CPB times with SIRS
Inappropriate hemodilution
Emboli
Avoiding hypothermia
Pulsatility
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22
Q

why is a high hct a risk factor

A

Decrease in microcirculatory blood flow

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23
Q

why is a low hct a risk factor

A

Decrease in renal oxygen-carrying capacity

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24
Q

why is hypothermia a risk factor

A

Lowers organ metabolic requirements

◦ most important target is brain

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25
Q

strokes & renal failure occurred more frequently at what temp

A

37C

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26
Q

is there a difference plasma renin activity or concentration of vasopressin in cold or warm CPB

A

no

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27
Q

Incidence of emboli and their associated clinical problems greatly reduced when what 2 things occur

A

stopped using bubble oxygenators

started using arterial / cardiotomy filter

28
Q

Most patients who develop post operative renal failure Suffer from what?

A

preexisting renal disease

29
Q

Most patients who develop post operative renal failure Have compromised renal perfusion secondary to what?

A

low cardiac output during perioperative period
◦ low renal perfusion pressure while on bypass
◦ low renal perfusion pressure off pump caused by renal vasoconstriction during low cardiac output states

30
Q

How many studies have conclusively shown that any pharmacological agent was effective in preventing acute renal failure requiring dialysis or death during or after cardiac surgery

A

None

31
Q

define Oliguria

A

Urine output less than 0.25 to 0.33 ml/kg/hour

32
Q

Decreased urine output could be result of what

A

kinked or obstructed catheter or stress-induced ADH

secretion

33
Q

what may be most important counter to renal hypoperfusion

A

Maintaining adequate perfusion pressure

34
Q

Dopamine

Method of action

A

stimulates dopamine specific receptors in the renal vasculature promoting vasodilation while inhibiting sodium reabsorption in the proximal tubule causing natriuresis

35
Q

Dopamine

Common dosage

A

0.5 mcg/kg/min

36
Q

Dopamine

Potential problems associated with use (3)

A
  1. research shows no actual renal benefit
  2. associated w/ an increased risk of post-op A-Fib, impairment of ventilatory drive in response to hypoemia and hypercarbia in spontaneously breathing patients secondary to carotid body depression
  3. suppression of circulating levels of anterior pituitary dependent hormones (prolactin)
37
Q

Dopamine

Summary of current research

A

When given btwn 3-10 mcg/kg/min- they observed no association btwn plasma concentration and infusion rate- concluding that the “renal” effect of the drug is unpredictable

38
Q

Fenoldopam

Method of action

A

A synthetic benzazepine derivative that binds selectively to DA1 receptors causing both systemic and renal vasodilation. Does not effect circulating levels of anterior pituitary dependent hormones (prolactin) or cause post-op A-Fib

39
Q

Fenoldopam

Common dosage

A

0.1 mcg/kg/min

40
Q

Fenoldopam

Potential problems associated with use

A

primarily given for HTN emergencies but research has not proven its effectiveness.

41
Q

Fenoldopam

Summary of current research

A

Unsure of the usefulness of this drug. One study showed it improved creatinine clearance, reduced amount of renal replacement therapy, decreased ventilation time and ICU stay. But another study showed no difference and that it should not be given prophylacticly.

42
Q

Dopexamine

Method of action

A

Synthetic sympathmimetic amine that stimulates adrenergic B2 and dopaminergic DA1 receptors causing both a systemic and renovasodilatory effect.

43
Q

Dopexamine

Common dosage

A

0.5-2.0 mcg/kg/min

44
Q

Dopexamine

Potential problems associated with use

A

only shows modest improvements in creatinine clearances

45
Q

Dopexamine

Summary of current research

A

shown to be a possible inhibitor of SIRS due to decreased release of proinflammatory cytokines

46
Q

Furosemide

Method of action

A

inhibits the active transcellular transport of chloride and sodium which produces natriuresis and associated diuresis. This reduces cellular oxygen demand and damage to the mTAL.

47
Q

Furosemide

Potential problems associated with use

A

routine use for oliguria or ARF- may worsen renal outcome and possible increase mortality

48
Q

Furosemide

Summary of current research

A

showed improvements in urine flow rates but no change in their overall dialysis-free survival.
One study showed it to increase renal impairment

49
Q

Mannitol

Method of action

A

causes ‘flushing’ effect of necrotic tubular debris, oxygen-free radical scavenging and improvement in medullary blood flow by reducing endothelial edema.

50
Q

Mannitol

Common dosage

A

0.25-1 g/kg before AoXc

51
Q

Mannitol

Potential problems associated with use

A

the use in prime to decrease tissue edema and promote urine formation is unproven as a renoprotectant

52
Q

Mannitol

Summary of current research

A

shown to decrease renal injury when administered before CPB and AoXc.

53
Q

Natriuretic peptides

Method of action

A

Atrial natriuretic peptide= hormone synthesized by cardiac atria that dilates afferent arterioles which increases glomular capillary hydrostatic pressure and GFR. Also inhibits reabsorption of Cl- and Na+, redistributes medullary BF, and blocks the effects of endothelin on the renal vasculature

54
Q

Natriuretic peptides

Potential problems associated with use

A

there appears to be no role for the use of ANP in the management of peri-op renal dysfunction

55
Q

Natriuretic peptides

Summary of current research

A

studies show an increase in dialysis-free survival only in patients with oliguric ARF. Patients nonoliguric ARF became worse due to resultant hypotension.

56
Q

Calcium channel antagonists: Nifedipine

Summary of current research

A

improves GFR, enhance the vasodilating prostaglindin E2, suppress the vasoconstricting protaglandin thromboxane B2, and modulate the vascular synthesis of endothelin

57
Q

Calcium channel antagonists: Felodipine

Summary of current research

A

showed improvements of GRF and active tubular transport when given during the second half of hypothermic CPB and stopped before rewarming

58
Q

Calcium channel antagonists: Diltiazem

Summary of current research

A

showed reductions in urinary microenzyme production, but little in the way of protection against ARF.

59
Q

Anti-inflammatory / antioxidant drugs: Corticosteroids

Potential problems associated with use

A

potential harm by worsening renal function due to the effects of hyperglycemia

60
Q

Anti-inflammatory / antioxidant drugs: Corticosteroids

Summary of current research

A

when dexamethasone was given before anesthesia induction and 8 hours after- there was induced renal injury as seen by the increase in urinary N-acetyl-glucosaminidase levels

61
Q

Anti-inflammatory / antioxidant drugs: Aspirin

Method of action

A

inhibition of thromboxane, a potent renovasoconstricor

62
Q

Anti-inflammatory / antioxidant drugs: Aspirin

Common dosage

A

pre-op low dose 100 mg- potential benefit for preserving post-op renal function

63
Q

Anti-inflammatory / antioxidant drugs: Aspirin

Potential problems associated with use

A

post op bleeding

64
Q

Anti-inflammatory / antioxidant drugs: Aspirin

Summary of current research

A

when stopping asprin 7 days before the procedure then getting 100 mg pre-op - there was less post-op renal insufficency at the expense of increased post-op bleeding

65
Q

Anti-inflammatory / antioxidant drugs: N-acetylcysteine

Summary of current research

A

studies fail to show any benefit of therapy in the at-risk patients undergoing CABG so it should not be used prophylacticly

Perf Tech 3 (15 decks)

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