Fluids and Electrolytes

Question 1

What percentage of our body weight is water, depending on age?

Answer 1

60% for the average adult, 80% for an infant, and 45% for an older adult.

Question 2

How much fluid in the body is extracellular?

Answer 2

1/3 (~15L)

Question 3

How much fluid in the body is intracellular?

Answer 3

2/3 (~27L)

Question 4

What is osmosis?

Answer 4

the movement of water across a semi-permable membrane from an area of high concentration to an area of low concentration.

Question 5

what is diffusion?

Answer 5

movement of solutes from an area of high concentration to an area of low concentration.

Question 6

what is active transport?

Answer 6

process that uses energy to move solutes from an area of low concentration to an area of high concentration

Question 7

explain hydro static pressure and osmotic attraction and how they move solutes in and out of the vascular space

Answer 7

hydro static pressure is the force exerted on the walls of the capillaries by the blood, forcing solutes out of the vascular space. proteins are too big to cross the membrane, so they increase osmolality, pulling other materials back into the vascular space

Question 8

how does damage to membranes lead to third spacing

Answer 8

damaged membranes are more permable and let proteins out, and therefore osmolality does not pull fluid back into the vascular space

Question 9

what is the tonicity of IV fluids measured against

Answer 9

the osmolality (concentration of solutes) in the blood

Question 10

what is an isotonic solution, and what does it do in the body?

Answer 10

has the same osmolality of blood, expands volume in the intravascular space

Question 11

give examples of isotonic solutions

Answer 11

0.9% NaCL lactated ringers

Question 12

who should not get ringers

Answer 12

pts with a ph >7.50, pts with liver disease

Question 13

what is special about D5W

Answer 13

it is isotonic in the bag but once in the body and the dextrose is metabolized it becomes hypotonic

Question 14

what is a hypotonic solution, and what does it do to the body?

Answer 14

osmolality is lower than blood, will push fluid into the intravascular space

Question 15

give examples of hypotonic solutions

Answer 15

0.45 NaCl, 2.5 dextrose in 0.45 NaCl

Question 16

what is a hypertonic solution and what does it do to the body

Answer 16

osmolality is greater than blood, pulls fluids from cells into vessels

Question 17

give examples of hypertonic solutions

Answer 17

3% NaCl, 10+ D5W

Question 18

what is a colloid

Answer 18

contains large molecules which do not pass through capillary membranes

Question 19

explain how thirst works

Answer 19

regulated by the osmolality of intrvascular space, they hypothalamus shrinks as a result of hypertonicity, which stimulates the feeling of being thirsty

Question 20

explain ADH

Answer 20

antidiuretic hormone, when glomular filtrate is hypertonic, osmoreceptors in the hypothalmus stimulate ADH to be released by the pituitary gland, making the renal collecting tubules more permable to water

Question 21

explain RAAS

Answer 21

renin-algiotensin-aldosterone-system, when low filtration rate, leads to ecreation of aldosterone, which increases sodium reabsorbtion

Question 22

explain baroreceptors

Answer 22

reduced stretch, activate SNS, leads to release of RAAS and ADH

Question 23

what electrolytes are found in ECF

Answer 23

sodium, calcium, chloride bicarb

Question 24

what electrolytes are found in ICF

Answer 24

potassium, magnesium, phosphorous

Question 25

what is the relationship between Mg, Phos, Ca

Answer 25

Mg and Phos move in the same direction, Ca moves opposite

Question 26

what is the relationship between K and Mg

Answer 26

is K is low Mg may also be low

Question 27

what is the relationship between Na and Cl

Answer 27

Move together

Question 28

What are the S/S of hyponatremia and how is it treated?

Answer 28

anorexia, vomiting, weakness, confusion and agitation, <110 can result in seizures, coma and death, due to cellular swelling

tx: depends on concentration, 0.9% NaCl unless severe, then 3% NaCl, have to monitor very closely for effects on brain, furosemide may be given concurrently to prevent fluid overload

Question 29

What are the S/S of hypernatremia and how is it treated?

Answer 29

signs are simular to hyponatremia, with addition of low grade fever, muscle twitching and hyperreflexia, but are secondary due to cellular dehydration

tx; hypotonic solution

Question 30

What are the S/S of hypochloremia?

Answer 30

same as hyponatremia, plus muscle weakness and slow shallow respiration

tx: as with hyponatremia

Question 31

What are S/S of hyperchloremia? tx?

Answer 31

same as hypernatremia plus deep laboured breathing

Question 32

What are causes and S/S of hypokalemia? ECG changes? Tx?

Answer 32

causes: thiazide and lasix diuretic, GI losses (nausea and vomiting), heart failure, kideny disease

S/S: potassium is needed for smooth muscle contraction, so when it is low it leads to muscle weakness, hyporeflexia, decreased GI motility, decreased respiratory function

ECG changes: depression of ST, bradycardia

Tx: oral or IV replacement, ECG monitoring, check magnesium levels too

Question 33

What are causes and S/S of hyperkalemia? ECG changes? Tx?

Answer 33

causes: shift out of cells due to burns or trauma, BB, K+ sparing diuretics, kidney failure means not able to excrete potassium

S/S: muscle weakness,

ECG: peaked t waves, sine waves

Tx: calcium gluconate, insulin/D50, salbutamol inhaler, kayexalate

Question 34

What are S/S of hypocalcemia? Tx?

Answer 34

makes the nervous system more excitable, positive Trousseaus sign (BP cuff) and positive Chvosteks sign (face), prolong QT, anxious/irritable, laryngo and bronchospasm

Tx: IV replacement

Question 35

What are S/S of hypercalcemia? Tx?

Answer 35

s/s: vague weakness, n/v, irritability, constipation

Tx: tx with fluids and diuretics, potentially dialysis

Question 36

What are S/S of hypophosphatemia? Tx?

Answer 36

s/s: weak, hemolysis, altered LOC

tx: replace

Question 37

What are S/S of hyperphosphatemia? Tx?

Answer 37

signs related to hypocalcemia

Question 38

What are S/S of hypomagnesia? Tx?

Answer 38

n/v, sedation, muscle weakness

Question 39

What are S/S of hypermagnesia? Tx?

Answer 39

depression of CNS, give calcium