Crr Week 7: Disorders Of Ecfv

Front 1

What is the total body water volume in the average man?

Back 1

42 L

Front 2

What is the intracellular fluid volume in the average man?

Back 2

28 L

Front 3

What is the extracellular fluid volume in the average man?

Back 3

14 L

Front 4

What is the insterstitial fluid volume in the average man?

Back 4

10.5 L

Front 5

What is the intravascular fluid volume in the average man?

Back 5

3.5 L

Front 6

What is the average effective arterial volume?

Back 6

0.7 L

Front 7

List the receptors of the afferent loop for total sodium volume control.

Back 7

1. Low pressure receptors (atrial and cardiopulmonary)
2. High pressure receptors (carotid, aortic arch)
3. Juxtaglomerular receptors

Front 8

List the effectors for controlling total sodium volume.

Back 8

1. Sympathetic nerves
2. Hypothalamus
3. Renin-angiotensin
4. ADH
5. ACTH
6. ANP

Front 9

Describe how low pressure receptors respond to volume expansion.

Back 9

1. Increase discharge rate impulses to hypothalamus
2. Renal sympathetic activity is decreased
3. ANP is released by atrial stretch, leading to natriuresis to lower BP.

Front 10

How are the low pressure receptors (atrial, cardiopulmonary) activated?

Back 10

Volume expansion

Front 11

How are the high pressure receptors (carotid, aortic arch) activated?

Back 11

Underfilling

Front 12

How do the high pressure receptors respond to arterial underfilling?

Back 12

1. Increase sympathetic activity and plasma NE levels
2. Increase BP and decrease natriuresis

Front 13

How does the body control extracellular fluid volume?

Back 13

By adjusting renal sodium excretion

Front 14

What causes renin release from the juxtaglomerular apparatus?

Back 14

Drop in effective arterial blood volume

Front 15

What are the actions of angiotensin II?

Back 15

1. Vasoconstriction
2. Efferent arteriolar contraction --> decreased GFR, increased GFR pressure --> increased Na+ reabsorption
3. Directly increases Na+ reabsorption at proximal tubule
4. Stimulates thirst
5. Stimulates aldosterone production

Front 16

What factors cause the release of vasopressin?

Back 16

1. Increased osmolality
2. Fall in EABV

Front 17

What are the actions of vasopression?

Back 17

1. Water reabsorption in collecting ducts
2. Na+ reabsorption in ascending limb of loop of Henle

Front 18

What is extracellular fluid volume determined by?

Back 18

Osmotically active solutes
(NOT by serum concentration of Na+)

Front 19

How does added NaCl change the plasma osmolality, extracellular volume, intracellular volume, and urine sodium?

Back 19

Added NaCl will have the following effects:

Plasma osmolality---> INCREASED
Extracellular volume --> INCREASED
Intracellular volume --> DECREASED
Urine sodium --> INCREASED

Front 20

How does added water change the plasma osmolality, extracellular volume, intracellular volume, and urine sodium?

Back 20

Added water has the following effects:

Plasma osmolality --> DECREASED
Extracellular volume --> INCREASED
Intracellular volume --> INCREASED
Urine sodium --> INCREASED

Front 21

How does added isonotic NaCl change the plasma osmolality, extracellular volume, intracellular volume, and urine sodium?

Back 21

Isotonic NaCl:

Plasma osmolality --> NO CHANGE
Plasma sodium --> NO CHANGE
Extracellular volume --> INCREASED
Intracellular volume --> NO CHANGE
Urine sodium --> INCREASED

Front 22

With osmoregulation, what is being sensed?

Back 22

Plasma osmolality

Front 23

With volume regulation, what is being sensed?

Back 23

Effective arterial blood volume

Front 24

Which sensors are involved in osmoregulation?

Back 24

Hypothalamus osmoreceptors

Front 25

Which sensors are involved in volume regulation?

Back 25

1. Carotid sinus
2. Afferent glomerular arteriole
3. Atria

Front 26

What is the effector for osmoregulation?

Back 26

ADH

Front 27

What are the effectors for volume regulation?

Back 27

1. Sympathetic NS
2. RAAS system
3. Vasopressin
4. ANP
5. Pressure natriuresis

Front 28

What is affected by osmoregulation?

Back 28

Water excretion and water intake (thirst)

Front 29

What is affected by volume regulation?

Back 29

Sodium excretion

Front 30

With heart failure, how is the EABV, ECFV, plasma volume, and cardiac output changed?

Back 30

EABV --> Decreased
ECFV --> increased
Plasma volume --> Increased
Cardiac output --> Decreased

Front 31

List 4 urinary causes of severe ECFV contraction

Back 31

1. Renal disease
2. Diurectic therapy
3. Osmotic diuresis
4. Adrenal insufficiency

Front 32

List 3 GI causes of severe ECFV contraction

Back 32

1. Vomiting
2. Diarrhea
3. Drainage

Front 33

List 2 skin causes of severe ECFV contraction

Back 33

1. Sweating
2. Burns

Front 34

List 4 signs of volume contraction that can be identified by physical examination

Back 34

1. Dry mucus membranes
2. Decreased skin tugor
3. Orthostatic BP changes
4. Decreased urine volume

Front 35

What is the therapy for treating ECFV contraction?

Back 35

1. Rehydration (volume and sodium, plasma expanders--dextran, full blood)
2. Treat primary cause

Front 36

List 4 clinically important causes of ECFV expansion

Back 36

1. Heart failure
2. Renal failure
3. Nephrotic syndrome
4. Severe liver disease

Front 37

List 4 conditions that will cause sodium retention due to arterial underfilling.

Back 37

1. Hypoalbuminemia
2. CHF
3. Cirrhosis
4. Vasodilation

Front 38

List 3 conditions that will cause sodium retention, despite arterial overfilling.

Back 38

1. Renal failure (no urine output)
2. Glomerulonephritis
3. Primary aldosteronism

Front 39

What is the difference between underfilled arterial conditions like CHF and overfilled arterial conditions like renal failure in the stimulation of renin, sympathetic NS, and ADH?

Back 39

Underfilled (CHF) --> Increased renin, sympathic NS, and ADH

Overfilled (CHF) --> Decreased renin, normal sympathetic NS and ADH
*When arteries are overfilled, body had no reason for these to be stimulated

Front 40

What is the result of CHF on BP and blood volume?

Back 40

BP --> Normal or decreased
Blood volume --> variable

Front 41

What is the effect of renal failure on BP and blood volume?

Back 41

(overfilled arteries)

BP --> High
Blood volume --> expanded

Front 42

List 5 signs of volume expansion that can be seen by physical examination

Back 42

1. Dependent edema
2. JVD
3. Rales on lungs
4. S3
5. Hepatomegaly

Front 43

What serum sodium concentration defines hypernatremia?

Back 43

> 145 meq/L

Front 44

How does the body respond to hypernatremia?

Back 44

1. Hypothalamus osmoreceptors sense high osmolality
2. ADH is released of posterior pituitary
3. ADH acts on collecting ducts of kidney to increase water reabsorption
4. Osmotic pressure decreases

Front 45

List 3 general causes of hypernatremia

Back 45

1. Addition of hypertonic NaCl solution
2. Loss of hypotonic fluid or pure water
3. No water intake

Front 46

List 3 categories of hypernatremia

Back 46

1. Normal-volume hypernatremia (loss of electrolyte free fluids-- loss of pure water)
2. High-volume hypernatremia (loss of Na+ containing, hypertonic solutions)
3. Low-volume hypernatremia (loss of hypotonic fluids)

Front 47

List 2 causes of normal-volume hypernatremia

Back 47

1. Renal loss (Central or nephrogenic diabetes insipidus)
2. Insensible loss (skin or lungs-- fever, hot room, hyperventilation)

Front 48

Plasma volume is what fraction of ECF volume and TBW?

Back 48

1/4 ECF
1/12 of TBW

Front 49

What are some possible lab findings in the urine of a patient with normal-volume hypernatremia?

Back 49

1. Large volume, dilute urine (<240 mOsm) --> Central or Neph. DI
2. Small volume, concentrated urine (>600 mOsm) --> insensible loss

Front 50

What are some causes of Central diabetes insipidus?

Back 50

1. Idiopathic
2. Neurosurgery or trauma
3. CNS tumor
4. Infiltrative disorder (CNS sarcoidosis)
5. Hypoxic encephalopathy, bleeding, infection..

*Impairment or complete loss of ADH secretion

Front 51

What are some causes of nephrogenic diabetes insipidus?

Back 51

1. **Chronic lithium treatment
2. Hypercalcemia
3. Persistent severe hypokalemia
4. Hereditary Neph DI (children)
5. Sickle cell, amyloidosis, myeloma...

Front 52

What is the treatment for central DI?

Back 52

dDVAP (desmopressin)

*Also must correct underlying disorder if possible

Front 53

What are some treatments for Nephrogenic DI?

Back 53

1. Thiazides
2. Dietary solute restriction (salt, protein)
3. Amiloride (lithium-induced NDI)
4. NSAIDs
5. Correct underlying problem

Front 54

What is the treatment for lithium-induced Nephrogenic DI?

Back 54

Amiloride

Front 55

What is the cause of high-volume hypernatremia?

Back 55

Exogenous solute addition
(NaHCO3, hypertonic NaCl, Salt poisoning in infants, sea water ingestion)

Front 56

List 3 treatments for high-volume hypernatremia?

Back 56

1. Diuretics
2. Replacement of water losses from diuretics
3. Dialysis (if concurrent renal failure)

Front 57

What is the most common cause of low-volume hypernatremia-- loss of hypotonic fluid or loss of pure water?

Back 57

Loss of hypotonic fluid

Front 58

What are the 2 major causes of hypotonic fluid loss?

Back 58

1. Renal losses (osmotic diuresis, diuretics)
2. GI losses (diarrhea, vomiting)

Front 59

List 4 symptoms of hypernatremia.

Back 59

1. Muscle weakness
2. Altered mental status
3. Focal neurological deficit
4. Coma and seizures

Front 60

Normally in hypernatremia, urine osmolality > ______ mosm/kg and urine volume drops to ______cc/day.

Back 60

Urine osmolality > 800mosm/kg
Urine volume drops to 500cc/day

Front 61

How do you treat hypernatremia incrementally over time?

Back 61

Correct half of deficit in 12-24 hours
Aim to lower serum Na by 0.5 meq/l/hr and no more than 12 meq/l in 24 hours

Front 62

What type of solution is given to treat patients with a hypotonic water deficit with concurrent hypotension?

Back 62

Half normal saline solution

Front 63

What type of solution is given to treat patients with a pure water deficit?

Why should you be especially careful with this?

Back 63

D5W given IV

*Hyperglycemia can result, so be careful with diabetic patients

Front 64

What serum sodium concentration defines hyponatremia?

Back 64

<135 mEq/L

Front 65

What are the 3 general classes of hyponatremia?

Back 65

1. True hyponatremia
2. Pseudohyponatremia
3. Dilutional hyponatremia

Front 66

Which class of hyponatremia is associated with hyperosmolality?

Back 66

Dilutional hyponatremia
(increased glucose, glycine, or mannitol causes increased water in ECV)

Front 67

What is the normal osmolality?

Back 67

285 - 290 mosm/kg H20

Front 68

What is the normal osmolar gap?

Back 68

10

Front 69

How do you calculate osmolality?

Back 69

Osm(calc) = 2Na + BUN/2.8 + Glucse/18

Front 70

How is the osmolar gap calculated?

Back 70

Osm gap = Osm(measured) - Osm(calculated)

Front 71

What does hyponatremia tell us about volume status?

Back 71

Nothing!
As a result of hyponatremia, ECF could be normal, increased, or decreased

Front 72

Usually hyponatremia does not occur unless the patient has both an impaired _________ and continued__________.

Back 72

Impaired capacity to excrete water
Continued intake of fluids

Front 73

In general, what are the two basic causes of hyponatremia, and which is the most common?

Back 73

1. Decreased renal ability to excrete solute free water <-- MOST COMMON
2. Massive water intake

Front 74

List 3 examples of massive water intake that lead to hyponatremia.

Back 74

1. Fresh water drowning
2. Psychotic water drinker
3. Beer potomani

Front 75

List 2 causes of impaired renal water excretion that will lead to hyponatremia.

Back 75

1. Decreased distal sodium delivery
(Decreased GFR, increased proximal reabsorption)
2. Increased back diffusion of water in collecting ducts
(ADH, decreased flow rate)

Front 76

What are some clinical conditions that result in hyponatremia?

Back 76

1. Sodium depletion
2. Drugs
3. Endocrine disorders (deficient aldost, cortisol, thyroxine)
4. SIADH
5. CHF
6. Renal failure
7. Cirrhosis
8. Stress
9. (+) pressure ventilation

Front 77

Water intoxication results when urine osmolality drops lower than _____mosmol/L.

Back 77

< 50 mosmol/L

*Kidneys are unable to excrete water, so it is reabsorbed along collecting ducts

Front 78

What is the normal osmotic load per day?

What are the most important osmoles to maintain this concentration?

Back 78

600 mosmol/day

Na+, urea (from protein catabolism)

Front 79

What is the cause of beer potomania?

Back 79

Beer has a high carbohydrate concentration and no sodium. Excessive consumption of carbohydrates blocks protein synthesis, decreasing urea production.
Thus, decreased amounts of sodium and urea ensues, impairing the kidneys' ability to excrete water.

Front 80

What kind of symptoms result from hyponatremia?

Back 80

CNS dysfuction
(confusion, lethargy, stupor, coma, and seizures)

Front 81

Explain the 3 different volume statuses that can be seen along with hyponatremia

Back 81

1. Hypovolumic (Both salt and water are lost, but more salt than water)
2. Euvolumic (some expansion of ECF due to water retension, but clinically no evidence of excess fluid)
3. Hypervolumic (excess water and salt, but more water compared to salt)

Front 82

Give some examples of hypovolumic hyponatremia.

Back 82

1. Urinary (renal disease, diuretics, adrenal insufficiency)
2. GI (vomiting, diarrhea, drainage)
3. Skin (sweating, burns)
4. Drainage of ECF (peritoneal, pleural)

Front 83

List 5 causes of euvolumic hyponatremia

Back 83

1. Hypothyroidism
2. Drugs
3. (+) pressure ventilaiton
4. Stress
5. SIADH

Front 84

What kind of hyponatremia does SIADH cause?

Back 84

Euvolumic hypernatremia

Front 85

What is the time difference between development of acute and chronic hyponatremia?

Back 85

Acute <48 hrs < Chronic

Front 86

As a rule, chronic hyponatremia is not symptomatic unless the serum sodium concentration is < _____mEq/L

Back 86

<120 mEq/L

Front 87

Are stupor and coma manifestations of chronic hyponatremia?

Back 87

No
Seizures and coma preclude continued water intake, which is required to maintain the hyponatremic state

Front 88

Central pontine myelinosis can be caused by rapid correction of which condition?

Back 88

Chronic hyponatremia