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PHM 602 Cardio-Renal > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Limitations of SCr

A
  • Dependent on muscle mass
  • Some tubular secretion of creatinine (not accurate measure of glomerular filtration)
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2
Q

Purpose of measuring BUN

A

When kidneys aren’t working properly (have low perfusion), they reabsorb more urea to increase plasma volume and increase kidney perfusion

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3
Q

BUN/SCr Ratio

A

Easiest way to look at someone’s volume status in a basic metabolic panel

  • Normal = 10:1 to 20:1
  • > 20:1 = decreased kidney perfusion
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4
Q

What is CrCl used for?

A

To estimate GFR

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5
Q

Urinary CrCl equation

A

(urine creatinine/serum creatinine) x (urine volume/time)

  • Used when CrCl is directly measured via 12 or 24 hour urinary collection
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6
Q

Cockcroft-Gault CrCl equation

A

[(140 - age) x IBW]/[72 x SCr] x 0.85 (if female)

Female IBW = 45.5 + (2.3 x height above 5 ft)
Male IBW = 50 + (2.3 x height above 5 ft)

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7
Q

Limitations of Cockcroft-Gault CrCl

A
  • Value can be different when using total body weight vs ideal body weight
  • Lags behind changes in kidney function by at least 1 day (not good for unstable changes in creatinine)
  • Overestimates true GFR
  • Less reliable for < 30 ml/min b/c more tubular secretion
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8
Q

What is CKD-EPI eGFR used for?

A

Used for chronic kidney disease staging and drug dosing

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9
Q

Difference between MDRD and CKD-EPI equation

A

MDRD = included race coefficient which introduced potential disparities in how kidney disease was staged

CKD-EPI = removes race from estimation process and calculates creatinine and cystatin C (decreased inaccuracies in CKD diagnosis and staging)

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10
Q

Limitations of CKD-EPI

A
  • Underestimates true GFR, especially at higher GFR
  • SCr must be stable
  • Less reliable for > 70 ml/min
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11
Q

Albuminuria Levels

A
  • Normal < 30 mg/day
  • Microalbuminuria = 30 - 299 mg/day
  • Macroalbuminuria > 300 mg/day
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12
Q

Role of kidney when you are dehydrated

A
  • Preserves as much salt and water as possible
  • Decreases urine volume and urine sodium
  • Increases urine specific gravity (concentrates urine)
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13
Q

Role of kidney when you have too much fluid in the body

A
  • Eliminates as much salt and water as possible
  • Increases urine volume and urine sodium
  • Decreases urine specific gravity (dilutes urine)
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14
Q

Obligate water loss

A

1600 ml/day

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15
Q

Glomerular filtration is reduced by?

A
  • Age
  • Renal disease
  • Congestive heart failure
  • Cirrhosis
  • Nephrotic syndromes
  • Volume depletion
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16
Q

Delivery of H2O to Loop of Henle is determined by?

A
  • GFR
  • Proximal tubule H2O
  • Na/Cl reabsorption
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17
Q

Na/Cl reabsorption at thick ascending limb is reduced by?

A
  • Loop diuretics
  • Osmotic diuretics
  • Interstitial disease

*This is the site of most of Na/Cl and water reabsorption. If you can inhibit this, you can inhibit the vast majority of sodium reabsorption

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18
Q

Na/Cl reabsorption at distal convoluted tubule is reduced by?

A

Thiazide diuretics

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19
Q

Permeability of Collecting Duct is increased by?

A
  • Vasopressin
  • Other drugs
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20
Q

Hypovolemic Physical Characteristics

A
  • Hypotension
  • Tachycardia (Lower BP and higher HR because there isn’t enough volume to fill the BV for them to have enough pressure against the BV walls to create normal BP)
  • Poor skin turgor
  • Slow capillary refill time
  • FeNa < 1% (normal = 1-2%)
  • FeUrea < 35% if patient is on loop diuretic
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21
Q

Hypervolemic Physical Characteristics

A
  • Hypertension (Blood volume is so large that it is pushing against the walls of the BV → higher BP)
  • Edema (peripheral and/or pulmonary) (The higher pressure will push fluids back into the interstitial spaces → edema)
  • Weight gain
  • Jugular venous distention
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22
Q

Hypotonic IV Fluids

A
  • D5W
  • 0.45% NaCl
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23
Q

Isotonic IV Fluids

A
  • 0.9% NaCl
  • Lactated Ringers
  • 5% albumin
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24
Q

Hypertonic IV Fluids

A

3% NaCl

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25
Q

When to use 5% albumin?

A

Hypoalbuminemia and/or sepsis

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26
Q

Balanced crystalloids vs Normal saline

A
  • Balanced crystalloid is closer to neutral pH, has contents closer to physiologic levels, showed decreased risk of death, need for renal replacement therapy, and persistent renal dysfunction
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27
Q

Oral Fluid Solutions (Gatorade, Powerade, Pedialyte) Tonicity

A

Hypotonic because most of the osmolality is derived from dextrose content which is rapidly metabolized in blood stream

*If a patient is really dehydrated and needs oral fluid supplement, Pedialyte is the best option because it is the only one that has reasonable electrolyte content

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28
Q

Normal maintenance fluid infusion rate

A

100 - 125 ml/hr

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29
Q

How to calculate maintenance fluid infusion rate

A

1500 + [20/every kg above 20 kg]

Divide by 24 hours to get ml/hour

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30
Q

When to use what type of IV fluid?

A

Replace fluid losses with the same type of fluid
- Hypotonic loss should be replaced with hypotonic fluids

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31
Q

What to do when patient is hemodynamically instable (low BP and high HR)

A

Bolus isotonic crystalloids or bolus iso-oncotic colloids until improvement in hemodynamics (to expand intravascular volume as quick as possible)

Once BP and HR are normal, go back to replacing fluid losses with the same type of fluids

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32
Q

Effects of different tonicity fluids in the body

A
  • Isotonic = stays in extracellular fluid
  • Hypotonic = shifts water into intracellular space
  • Hypertonic = shifts water out of intracellular space
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33
Q

When to give maintenance fluid rate?

A
  • Patient is NPO for procedure
  • CKD with mild dehydration
  • ESRD with severe dehydration
  • HF with moderate dehydration
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34
Q

When to give less than maintenance fluid rate

A
  • 0.75 x = CKD, chronic liver disease, mild heart failure
  • 0.5 x = severe heart failure, end-stage renal disease
35
Q

When to give more than maintenance fluid rate

A
  • 1.25 x = mild dehydration
  • 1.5 x = moderate dehydration
  • 2 x = severe dehydration
  • large volume boluses = hemodynamic shock
36
Q

Hyponatremia Clinical Presentation

A
  • Low Na
  • Symptoms dependent on Na concentration and the rate of change of Na
  • Chronic and/or mild hyponatremia → asymptomatic
  • Acute hyponatremia → more severe presentation of symptoms
  • Neurologic changes (Headache → Confusion → Lethargy → Seizures → Coma)
  • May be associated with increased/decreased/normal ECF volume
37
Q

Drugs that cause SIADH

A
  • SSRIs
  • Carbamazepine
  • Opiates
38
Q

Corrected Na equation

A

Measure Na + 1.6 x (every 100 mg/dl glucose above 100)

39
Q

How to correct hyponatremia

A
  • Stop symptoms and prevent seizures
  • Get corrected Na to > 120
  • Correct Na to normal range (135 - 145)

Maximum correction = 6 - 12 per day or 0.25 - 0.5 per hour

40
Q

What happens when you rapidly correct hyponatremia?

A

Leads to osmotic demyelination syndrome (central pontine myelinolysis)

41
Q

What is isotonic hyponatremia

A

Decreased serum Na, normal measured serum osmolality

42
Q

Causes of isotonic hyponatremia

A

Lab error

43
Q

What is hypertonic hyponatremia

A

Decreased serum Na, increased measured serum osmolality

44
Q

Causes of hypertonic hyponatremia

A

Hyperglycemia

  • Elevated glucose in intravascular space pulls water out of the intracellular space which lowers Na in the extracellular space
45
Q

Treatment of hypertonic hyponatremia

A

Reduce serum glucose (treat hyperglycemia with insulin) and recheck sodium

46
Q

What is Hypotonic Euvolemic Hyponatremia

A

Increased TBW, no change in Na

47
Q

Causes of Hypotonic Euvolemic Hyponatremia

A
  • SIADH (Overactivity of ADH → water from urine is reabsorbed → concentrated urine and excess free water in ECF)
  • Drug-induced SIADH
  • Psychogenic Polydipsia (Psychiatric disorder where patient drinks too much water (>20L/day))
48
Q

Treatment of Hypotonic Euvolemic Hyponatremia

A
  • Treat underlying disorder
  • Water restriction 1000-1200 mL/day
  • Vasopressin receptor antagonist (rarely used)
  • Sodium chloride + loop diuretic
49
Q

What is Hypotonic Hypervolemic Hyponatremia

A

Big increase in TBW, increase Na

50
Q

Causes of Hypotonic Hypervolemic Hyponatremia

A
  • Cirrhosis
  • HF
  • Nephrotic syndrome
51
Q

Treatment of Hypotonic Hypervolemic Hyponatremia

A
  • Treat underlying disorder
  • Slow progression of disorder
  • Water restriction 1000 - 1200 mL/day and salt restriction 2000 mg/day
  • Loop diuretics
  • V2 receptor antagonist (rarely used)
52
Q

What is Hypotonic Hypovolemic Hyponatremia

A

Decrease TBW, big decrease in Na

53
Q

Causes of Hypotonic Hypovolemic Hyponatremia

A

GI Losses (Diarrhea/Vomiting):
- Isotonic or hypotonic fluid loss → stimulation of thirst (AVP) → administration of hypotonic fluid with continuing fluid loss → decline in sodium concentration
- Urinary Na < 20 mEq/L

Thiazide Diuretics:
- Urinary Na > 20 mEq/L
- High urine Na because thiazide is stimulating the kidneys to secrete sodium

54
Q

Treatment of Hypotonic Hypovolemic Hyponatremia

A

0.9% sodium chloride (replace fluid and sodium)

55
Q

What is Acute Severe Hypotonic Hypovolemic Hyponatremia

A

Rapid decline in serum Na < 110 mEq/L

Severe symptom = seizure

56
Q

Treatment of Acute Severe Hypotonic Hypovolemic Hyponatremia

A
  • Hypertonic saline (3% or 23.4% NaCl) can be used to initially manage
  • Desired Na = 125 - 130 mEq/L to avoid rapid overcorrection
  • May combine with loop diuretic to enhance free water clearance (not recommended)
  • Stop once serum Na > 120 mEq/L or severe symptoms resolve
57
Q

Demeclocycline dosing

A

300 mg PO BID-QID

58
Q

Risks of Demeclocycline

A
  • Risk of renal tubular damage and AKI (this drug is not used anymore because of these risks)
  • Avoid in children < 8 years and pregnancy (changes in tooth development)
59
Q

Use of Conivaptan

A

V1, V2 receptor antagonist (IV only)

Used for acute euvolemic hyponatremia (FDA indication)

60
Q

Tolvaptan dosing

A

15 - 60 mg PO QD

61
Q

Uses of Tolvaptan

A

Hyper and euvolemic hyponatremia due to HF, cirrhosis, or SIADH

Autosomal dominant polycystic kidney disease

62
Q

Tolvaptan AE

A
  • Thirst
  • Polyuria (this drug prevents you from responding to ADH and water is not reabsorbed and is eliminated in urine → polyuria)
  • Constipation

BBW = hepatotoxicity

63
Q

What is hypovolemic hypernatremia

A

Water loss&raquo_space; sodium loss

Decrease Na/Big decrease TBW

64
Q

Causes of hypovolemic hypernatremia

A

Over-diuresis

65
Q

Clinical Presentation of hypovolemic hypernatremia

A
  • Orthostasis
  • Hypotension
  • Tachycardia
  • Dry mucous membranes
66
Q

Treatment of hypovolemic hypernatremia

A
  • Normal saline IV until BP/HR stable
  • Then free water replacement
67
Q

What is Euvolemic Hypernatremia

A

Water loss

Neutral Na/decrease TBW

68
Q

Causes of Euvolemic Hypernatremia

A

Diabetes insipidus

69
Q

Clinical Presentation of Euvolemic Hypernatremia

A
  • Polyuria
  • Polydipsia
  • Lethargy
  • Seizures
70
Q

Treatment of Euvolemic Hypernatremia

A
  • Free water replacement
  • Vasopressin (DDAVP)
71
Q

What is Hypervolemic Hypernatremia

A

Sodium gain > water gain

Big increase Na/Increase TBW

72
Q

Causes of Hypervolemic Hypernatremia

A

Sodium overload

73
Q

Clinical Presentation of Hypervolemic Hypernatremia

A

Peripheral and pulmonary edema

74
Q

Treatment of Hypervolemic Hypernatremia

A

Free water + loop diuretic

75
Q

Free Water Deficit Equation

A

[0.6/kg] x [(Na absorbed/140) - 1]

76
Q

How to administer free water replacement for hypernatremia

A
  • Administer 50% of free water deficit in first 24 hours, then administer 50% over 2 - 3 days

Close monitoring of serum sodium is necessary

Don’t exceed a sodium correction greater than 6 - 12 mEq/L/day (risk of cerebral edema)

77
Q

How does renal disease, cardiac dysfunction, liver disease, and excessive salt intake cause edema?

A

They decrease effective circulatory volume which stimulates RAAS –> increases sodium and water reabsorption at kidneys

  • Increases capillary hydrostatic pressure
  • Decreases protein production (liver disease) or excessive albumin excretion (renal disease) –> decreased oncotic pressure
78
Q

Treatment of edema

A
  • Salt restriction = 1,000 - 2,000 mg/day
  • Optimize cardiac function
  • Pharmacologic diuresis
79
Q

How does diuresis help treat edema?

A

Edema causes ECF to expand

Diuresis removes fluid from intravascular compartment and over time, equilibrium between intravascular and interstitial compartments occur

80
Q

Types of Diuretics

A

1) Carbonic anhydrase inhibitors (acts in proximal convolutes tubule and blocks the reabsorption of sodium and bicarb)

2) Loop diuretics (in ascending loop of henle and blocks NKCC channel)

3) Thiazides (in distal convoluted tubule and stops reabsorption of Na)

4) K Sparing Diuretics (in collecting duct and blocks aldosterone –> inhibits sodium reabsorption)

81
Q

Where do loop diuretics act?

A

Luminal membrane of ascending loop of henle

82
Q

Types of Loop Diuretics (with IV and PO dosing)

A

Furosemide (Lasix) = 20 mg IV, 40 mg PO

Bumetanide (Bumex) = 1 mg IV, 1 mg PO

Torsemide (Demadex) = 20 mg IV, 20 mg PO

Ethacrynic Acid (Edecrin) = 50 mg IV, 50 mg PO

83
Q

AE of Loop Diuretics

A

Hypokalemia, metabolic alkalosis, renal injury due to dehydration, ototoxicity at high doses, sulfa reactions (use ethacrynic acid if sulfa allergy)

PHM 602 Cardio-Renal (1 decks)

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