Lytes Flashcards
1
Q
How is TBW calculated?
A
as Kg x 0.6 = Liters total body water
2
Q
How much of total body water is intracellular?
A
2/3rds
3
Q
How much of extracellular body water is intravascular?
A
25%
4
Q
How is total body water distributed?
A
- 2/3rds intracellular
- 1/3rd extracellular
- 25% intravascular
- 75% interstitial
5
Q
What is the blood volume of an average adult? average child?
A
- 70kg male has 5L blood volume
- children have 80cc/kg blood volume
6
Q
What is the makeup of LR?
A
- 130 mEq sodium
- 4 mEq potassium
- 2.7 mEq calcium
- 109 mEq chloride
- 28 mEq bicarb
7
Q
How much sodium and potassium does a person need each day?
A
- 0.5 - 1.0 mEq of potassium
- 1.0 - 2.0 mEq of sodium
8
Q
How many calories are in a liter of D5?
A
- D5 = 50g of dextrose
- dextrose has 3.4kcal/g
- total = 170 kcal
9
Q
How is serum osmolality calculated?
A
- Osm = 2 x Na + glucose/18 + BUN/2.8
- simplifies to 2 x Na + 10
10
Q
How can you differentiate SIADH from excess free water?
A
- calculate serum osmolality (2 x Na + 10) and compare it to urine osmolality
- if urine osmolality is lower than likely excess free water
- if urine osmolality is higher than likely SIADH
11
Q
How is SIADH treated?
A
- fluid restriction
- normal saline
- vaptans (vasopressin antagonists)
- demeclocycline
12
Q
What are the two most likely causes of hypernatremia?
A
dehydration and diabetes insipidus
13
Q
How is free water deficit calculated?
A
(actual Na - desired Na)/desired Na x kg x 0.6
14
Q
What are the symptoms of hypocalcemia?
A
- weakness
- perioral tingling
- Chovstek’s sign (tap on facial nerve and get a perioral twitch)
- Trousseau’s sign (carpal pedal spasm with blood pressure cuff)
15
Q
How is calcium corrected for albumin?
A
- normal albumin = 4
- add 0.8 to calcium for every 1 albumin is below 4
- e.g. if albumin is 2, add 1.6 to calcium
