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Co-Existing & Basic Principles 2016 * > Renal > Flashcards

Flashcards in Renal Deck (93):
1

These factors will result in prostaglandin synthesis by the kidneys

Renal ischemia, renal hypotension, and physiological stress

2

This common drug used for post-op pain relief should be avoided in those at risk for medullary ischemia. Why?

Ketorolac (Toradol) This is because it is a powerful NSAID, which drastically reduces prostaglandin synthesis, putting the kidneys at risk for ischemia

3

Low dose dopamine will do this, but not this

Will have positive inotropic effects, which increase UO. Will not decrease the incidence of ARF, dialysis, or mortality

4

The kidneys are able to autoregulate over this range of MAPs

80-180 Some say up to 200 Either way, kidneys are very sensitive to a reduction in MAP Also, may be higher than 80 if the patient has chronic HTN

5

Surgical stimulation can cause release of this hormone

ADH This will cause a drop in UO

6

This will cause aldosterone release

baroreceptor response to volume depletion

7

In hypotension, blood will be shunted (towards/away) from the kidneys

Away from the kidneys! Towards the vital organs

8

What ion are we concerned about in renal failure?

Floride. Free fluoride ions cause tubular injury and loss of concentrating ability (can result in ARF)

9

Ranking of volatile agent effects on the kidney

Methoxy>Enflu>Sevo>Iso>Des>Halo (MESID H)

10

We prefer the use of these IAs in renal failure patients

Iso and des These have negligible effects on renal function

11

This is the minimum amount of gas flow that should be given with Sevo

2L to prevent compound A formation

12

BUN > ___ is indicative of decreased GFR

50

13

These factors may cause GFR to rise despite a normal GFR

High protein diet GI bleed Febrile illness Dehydration

14

What is the most common cause of high BUN

CHF secondary to the reabsorption of BUN Low CO causes lows kidney perfusion. Kidneys try to correct perceived fluid deficit by reabsorbing urea.

15

There is a __-__ hour lag time after a change in GFR before the increase creatinine levels are seen

8 - 17

16

What test is the most reliable estimate of GFR?

Creatinine clearance

17

Why is anemia common in renal failure?

1) Decreased EPO production 2) Build-up of toxins decreases the lifespan of RBCs

18

Chronic renal patients will usually have an increased or decreased CO?

Increased to compensate for the anemia

19

Hemoglobin levels as low as __-__ are common for renal patients, so don't freak out

5-8

20

Renal patients usually have fucked up coags. Which coags are fucked up and why?

PT, PTT, and bleeding time. These are fucked up because they have shitty vWF. Treat this by replacing vWF.

21

How can you treat the fucked up coags seen in renal dysfunction?

Replace the vWF! 1) Desmopressin .3-.4mg/kg over 30 min) - Desmopressin will increase the release of vWF from endothelial cells 2) Cryoprecipitate (remember that this contains factor VIII, XIII, fibrinogen, and whaddup --> vWF!)

22

The hyperkalemia seen in RF can result in these EKG changes

Peaked T waves, ST depression, prolonged PR interval and QRS complex, heart block, and V-fib

23

Hypermagnesemia resulting from RF can cause

Coma and CNS depression Prolongs the duration of NMBs

24

Why do we use a microdripper to give fluids in renal patients?

To make sure we don't fluid overload them

25

Why does RF cause HTN?

1) Renin release by the diseases kidney 2) High intravascular fluid volume d/t inappropriate handling of sodium and water

26

RF can lead to ____ pericarditis and cause

uremic pericarditis tamponade

27

Hypocalcemia causes this on EKG

Prolonged QT

28

Digitalis toxicity produces this on EKG

Shortened QT and depressed ST

29

These meds are excreted via the kidneys unchanged and are contraindicated in RF

Gallamine (100% renal elimination) and phenobarbital

30

Is UO predictive of post-op renal insufficiency?

No

31

What can happen if you give too much fluid to your anuric renal patients?

CHF and pulmonary edema

32

UO during surgery should be maintained at this rate

0.5cc/kg/min If it falls, we can give 5mg of lasix

33

A 50% increase in plasma creatinine means

A 50% reduction in GFR

34

This is the source of creatinine

Skeletal muscle

35

We are concerned about K+ when it is over

5

36

When is vasopressin released?

Released by the posterior pituitary in response to high serum osmolarity and acts on the kidneys

37

This is the dose for low-dose dopamine

1-2mcg/kg/min

38

Effect of neuraxial anesthesia in renal dysfunction

• T4-T10 sympathectomy will decrease the release of catecholamines, renin, and vasopressin (ADH) o This is because we’re causing vasodilation and blocking the sympathetic response! o Make sure to pre-hydrate before placement! • Key to maintenance of renal blood flow and GFR is you have to maintain renal perfusion pressure – fluid boluses etc. o Remember that proper RBF is dependent on MAP

39

Effect of PPV on renal function, and how we can over come this

• The higher the PIP and PEEP the greater the decrease in RBF, GFR, and urine flow rate o Probably because PPV will decrease venous return and CO We can overcome this by hydrating.

40

Creatinine Clearance

Normal is 125mL/min •

41

What may a CXR show in the patient with renal failure?

• LVH o Determine presence of hypertensive cardiovascular disease • Pericardial effusion (from uremic pericarditis) • Uremic pneumonitis- RF patients have chronic pulmonary edema → fluid overload, shitty heart function, and leaky capillaries

42

Avoid these NMBs in renal failure

d-tubocurarine, metocurine, gallamine

43

What is the most common cause of death in renal failure?

Infection Make sure to use aseptic technique!!

44

IAs for RF

 Halothane  Avoid- High K+ & acidosis-> myocardial irritability  Enflurane  Avoid- fluoride concern  Sevoflurane  Controversial: some practitioners remain concerned regarding Compound A and fluoride  Isoflurane/Desflurane  Volatile agents ideal-no dependence on kidney for elimination  Accelerated induction and emergence seen with severe anemia  Anemia results in decreased solubility of the IA

45

Ventilation goals in RF

 Hypoventilation exacerbates acidosis  Hypercapnia predisposes to cardiac arrhythmias from acidosis  Alkalosis shifts oxy-hgb curve to left- less O2 available to tissues  Overall, we want to maintain normal acid/base balance  Remember too that they are anemic and we want to do this to keep the O2 dissociation curve to the right!! Remember that high PIP and PEEP will decrease RBF

46

This is the pressor of choice for renal pts

Ephedrine

47

What's the deal with H2 blockers and renal failure?

H2 blockers are highly dependent on renal excretion

48

When does cystoscopy require more than local anesthesia?

If the bladder if being inflated (consider RA or GA)

49

Lithotomy position for cystoscopy puts you at risk for these nerve injuries

All major legs nerves except LFC (Sciatic, common peroneal, femoral, saphenous, and obturator)

50

RA for cystoscopy

Need T10 block Spinal preferred d/t brief nature of the surgery Will not abolish the obturator reflex (can only be blocked by muscle relaxants, which we don't use with a regional technique)

51

GA for cystoscopy

Short case (15-20 min) LMA ok to use

52

S/S associated with TURP syndrome

headache, restlessness, confusion, seizure, dyspnea, cyanosis, arrhythmias, hypotension with bradycardia

53

Irrigating fluids used for TURP

glycine, sorbitol, or mannitol

54

How to prevent TURP syndrome

Limit irrigating fluid height to 40cm above prostate (job of the urologist) Limit resection time to less than 1 hour

55

Treatment for TURP syndrome

EARLY DETECTION!!  Fluid restriction  Loop diuretic  To correct fluid overload and hyponatremia  Hypertonic solution if hyponatremia present. 100cc 3% saline over 1-2 hours. Administer based on patients serum sodium (Ideally >120)  Hyponatremia occurs d/t large absorption of this fluid that doesn’t contain lytes  Results in cerebral edema  Treat seizures with midazolam, thiopental or phenytoin (if glycine used consider a trial of magnesium)  Intubate if pulmonary edema has occurred (from volume overload)

56

Regional blockade level needed for ESWL

T6

57

Why is GA preferred for ESWL?

Ability to control diaphragmatic excursion (Jet ventilation)

58

Coagulation considerations in RF

o Increased bleeding despite normal PT, PTT, and Bleeding Time • Caused by release of defective von Willebrand factor • Rx- Desmopressin (0.3-0.4 mg/kg over 30 min) or cryoprecipitate o Blood warmer- set up and have ready to go

59

When is vasopressin released?

It's released by the posterior pituitary in response to an increase in serum osmolarity

60

Something to remember before doing neuraxial anesthesia in renal failure

• T4-T10 sympathectomy will decrease the release of catecholamines, renin, and vasopressin (ADH) o This is because we’re causing vasodilation and blocking the sympathetic response! o Make sure to pre-hydrate before placement!

61

Kidney functions

Fluid, pH, ion homeostasis Waste removal- urea, uric acid, creatinine, meds, toxins Endocrine- RAAS system, EPO, 1,25 D3--> active vitamin D, Prostaglandin production

62

Hypovolemic urine production

SNS and angiotensin II--> vasoconstrictive decrease in GFR and increase in Na+ reabsorption Aldosterone increases Na+ reabsorption ADH increases H2O reabsorption

63

Hypervolemic urine production

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

64

Normal renal autoregulation

about 80-200 mmHg

65

Most anesthetic agents lead to

Decreased GFR, UO, RBF, and e-lyte excretion All major kidney functions affected

66

Surg/Anesthesia effect on ADH, Aldosterone, RAAS system

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

67

Prostaglandins have what effect on the renal system

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

68

Low dose dopamine is

voodoo medicine

69

T4-T10 sympathectomy will

Decrease catecholamines, renin, and ADH Need fluid boluses to maintain RBF and GFR

70

Which gas can create compound A

Sevo Maintain flows over 2L

71

Which gases have negligible levels of free fluoride ion from metabolism

Iso and Des Methoxy>Enflu=Sevo are the worst No evidence Sevo cause injury though

72

PPV

More PIP/PEEP, less RBF/GFR/UO Hydration will largely overcome this

73

Periop oliguria is defined as

74

Pre-op eval

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

75

Renal function tests

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)

76

BUN

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

77

Plasma Cr

8-17 hour lag after a GFR change Suggestive of ARF 50% increase indicates 50% decrease in GFR

78

Cr clearance

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

79

Chronic RF Hgb hovers around

5-8g/dl

80

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

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

81

Hyperkalemia common, what EKG changes does it produce

Peaked T, long PR, long QRS, ST depression HB and V-fib can result

82

HyperMg leads to

CNS depression and coma

83

high or low pH in CRF

low, can't excrete H+ ions

84

CXR for

HTN CV disease, pericardial effusion, uremic pneumonitis

85

Dig tox EKG

Short QT, ST depression

86

Hypocalcemia EKG

Long QT

87

RF and drugs

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

88

Common anesthetic drugs to use with caution in RF

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

89

Opioid of choice in RF

Fentanyl Remi also ok

90

Bad opioids in RF

Meperidine, morphine, hydromorphone

91

Muscle relaxants to avoid in RF

d-tubo, metocurine, gallamine, pancur, pipecur, doxacur Vec, roc ok (30% renal), but may see longer effect

92

Effects of Anesthetics on Normal Kidney

  • ADH release d/t surgical stimulation will ↓ U/O (and promote the reabsorption of H20)
  • Aldosterone release → baroreceptor response to volume depletion
  • Autoregulation may be affected under GA
    • Lower limits of autoregulation around 80 mmHg
  • Hypotension
    • caused by agents shunts blood away from kidney
    • Any ↓ in RBF causes release of renin → renal vasoconstriction & SNS stimulation further ↓ RBF 
    • with low pressure in anesthesia = get preferential efferent vasoconstriction so that the GFR is increased
    • massive hypotension → get afferent vasoconstriction and dramatic decreased GFR

93

Extra caution with succs because

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