electrolytes Flashcards
(91 cards)
1
Q
Total body water is _____ of total body weight
A
60%
2
Q
Intracellular volume is _____ total body weight
A
40% or 2/3
3
Q
Extracellular volume is _____ total body weight
A
20% or 1/3
4
Q
Extracellular is split up into what 2 fluid volumes?
A
Interstitial 75%
Plasma volume 25%
5
Q
TBW is ___% of a man’s weight
TBW is ___% of a woman’s weight
TBW is ___% of an infant’s weight
A
55%
45%
80%
6
Q
Obese individuals have _____ TBW per weight than non-obese individuals
A
less
7
Q
Fluid compartments are divided by
A
water-permeable membranes.
8
Q
Intracellular space is separated from the extracellular space by the
A
cell membrane
9
Q
The ______ _______ separates the components of the extracellular space.
A
Capillary membrane
10
Q
all of the fluid compartments are trying to reach equilibrium, what allows this to not happen?
A
membranes
11
Q
the intracellular fluid compartment has high concentrations of
A
potassium
phosphate
magnesium
12
Q
in the intracellular fluid compartment, what is the primary cation
A
potassium
13
Q
in the intracellular fluid compartment, what is the primary anion
A
phosphate
14
Q
What maintained the high concentration of K+ in the ICP
A
Na, K, ATPase (3Na in:2 K out)
15
Q
Extracellular fluid compartments have high concentrations of
A
Na and Cl
16
Q
in the extracellular fluid compartment, what is the primary cation
A
Na
17
Q
in the extracellular fluid compartment, what is the primary anion
A
Cl
18
Q
1/4 of ECV is high concentration of
A
plasma proteins (albumin
19
Q
Capillary membrane essentially impermeable to plasma proteins and they remain in the _______ ________
A
vascular space
20
Q
interstitial fluid is _____ of ECV
A
3/4
21
Q
What is a normal serum osmolality
A
285-295
22
Q
How do you calculate a serum osmolality
A
(2(NA)) + (BUN/2.8) + (Glucose/18) = serum osmolality
23
Q
Why is the intravascular fluid space the chief focus of fluid therapy?
A
Because it is an accessible fluid compartment
24
Q
Starling forces: hydrostatic pressure in the capillaries (Pc) is the
A
blood pressure
25
Starling forces: Hydrostatic pressure in the interstitium (Pi) is
low
| slightly negative d/t lymphatics
26
What is the main determinant of osmotic pressure?
albumin
27
a positive net driving force favors
filtration into tissues (interstitial fluid)
28
a negative net driving force favors
reabsorption into vasculature
29
Factors affecting fluid movement: osmolarity
An expression of the number of osmoles of a solute in a LITER of solution
30
Factors affecting fluid movement: osmolality
An expression of the number of osmoles of a solute in a KILOGRAM of solvent
31
Factors affecting fluid movement: tonicity
How a solution affects cell volume
For example – isotonic, hypertonic, hypotonic
Isotonic solutions approximately 285 mOsm/L
32
How does a hypertonic solution more fluid
fluid moves out of cell (shrinking cell)
33
How does a hypotonic solution move fluid
fluid moves into the cell (can burst)
34
Isotonic osmolality should be the same as
serum osmolality
35
What is the difference between hypovolemia and dehydration?
HYPOVOLEMIA
Loss of extracellular fluid
Absolute loss of fluid from the body
Reduced circulating volume
DEHYDRATION
Concentration disorder
Insufficient water present in relation to sodium levels
36
What is hypervolemia?
Excess of fluid volume in an isotonic concentration
Not usually a problem in surgical patients
37
What type of surgical patients would you see hypervolemia in?
CHF
Renal Failure
Overhydration with isotonic fluids
38
_____ and ____ are responsible for the normal osmotic activity of the ECF
Na and Cl
39
All gain/loss of Na+ is accompanied by gain/loss of
water
40
Na:
intracellular
Extracellular
intracellular 25
Extracellular 140
maintained by Na, K, ATPase pump
41
Lack of permeability to sodium changes the osmotic gradients between fluid compartments, leading to precedence of sodium over plasma proteins as the most important osmotically active substance influencing the _____ _______ of the brain
water content
42
What is the most common electrolyte abnormality in hospitalized patients
hyponatremia
| can be caused by a loss of Na or to much water
43
What are some S/S of hyponatremia?
headache, malaise, agitation, coma, cerebral edema (MOST signifiant), confusion
Anorexia, N/V
cramps, weakness
44
What are some causes of hyponatremia?
```
Vomiting
Diarrhea
Diuretics
Adrenal insufficiency
Syndrome of inappropriate secretion of antidiuretic hormone
Renal failure
Water intoxication
CHF
Liver failure
Nephrotic syndrome
```
45
Treatment of hyponatremia
fluid restriction
admin of hypertonic saline AND osmotic or loop diuretic
3% saline if symptomatic
46
How quickly should Na be replaced?
no more than 1-2 meq/hr (no more than 10 in 24 hours)
47
What happens if you correct Na levels too rapidly
Correction of serum sodium levels too rapidly can result in neurologic damage and myelinolysis!!!
48
Most common cause of hypernatramia is
excessive loss of water or inadequate water intake
49
What else can cause hypernatremia
Exogenous Na+ load
Primary hyperaldosteronism
Diabetes insipidus
Renal dysfunction
50
S/S of hypernatremia
thirst, weakness, seizure, hallucinations, irritability, disorientation, coma, intracranial bleeding
hypervolemia
polyuria or oliguria, renal insufficiency
51
treatment for hypernatremia
Correction of hypernatremia is accomplished by replacing the water deficit
Plasma sodium should be decreased by 1-2mEq/hr until the patient is clinically stable.
52
Which electrolyte is largely responsible for resting membrane potential
potassium
53
how is potassium balanced
GI absorption and renal excretion
54
Causes of hypokalemia
```
Gastrointestinal losses
Systemic alkalosis
(Diabetic ketoacidosis) wrong
Diuretic therapy
Sympathetic nervous system stimulation
Poor dietary intake
```
55
the most common electrolyte abnormality encountered during clinical practice
hypokalemia
56
CV manifestations of hypokalemia
ST-segment depression
Presence of U wave
Flattened or inverted T waves
Ventricular ectopy
57
neuromuscular manifestations with hypokalemia
Weakness ( respiratory muscle)
Decreased reflexes
Confusion
58
what will you see with a K < 2.5
paresthesia, depressed deep tendon reflexes, fasciculations, muscle weakness
59
Below what K level do you question whether the surgery needs to be done now
<3
60
At what K level do you start to see U waves on the EKG
2
61
Treatment for hypokalemia
IV potassium supplements (up to 40mEqs can be given per hour)
62
What do you NOT want to do when a patient has hypokalemia
Avoid hyperventilation of the lungs (makes you more alkalotic and drives K into cells)
Avoid glucose containing IV solutions (If you give glucose, body produces more insulin – drive K into cells )
Avoid rapid infusion of IV K+ supplements
63
Causes of hyperkalemia
Renal failure
Potassium-sparing diuretics
Excessive IV K+ supplements
Excessive use of salt substitutes (Mrs Dash)
```
Metabolic or respiratory acidosis
Digitalis intoxication
Insulin deficiency
Hemolysis
Tissue and muscle damage after burns
Administration on succinylcholine
```
64
CV manifestations of hyperkalemia
```
Tall, peaked and elevated T waves
Widened QRS complex
Prolonged PR interval
Flattened or absent P wave
ST segment depression
Cardiac arrest
tachycardia
Vfib
```
65
Treatment for hyperkalemia
Insulin and glucose to shift K+ into cells
IV calcium to antagonize cardiac effects of hyperkalemia
albuterol, hyperventilate
66
What is the upper limit of K for elective procedures
5.5
67
Where is Magnesium stores
___ - ____% in muscle & bones
____% in cells
____% in serum
40-60%
30%
1%
68
Where does regulation of magnesium occur
intestines and kidneys
69
T/F: Mag is a cofactor in enzymatic reactions (Energy metabolism, protein synthesis, neuromuscular excitability, function of NA-K-ATPase)
True
70
Causes of hypomag
```
Inadequate dietary intake of magnesium
TPN without magnesium supplementation
Starvation
Gastrointestinal losses
Diarrhea
Fistulas
Nasogastric suctioning
Vomiting
Chronic alcoholism
```
71
ECG changes with hypomag
```
Flat T-waves
U-waves
Prolonged QT interval
Widened QRS
Atrial and Ventricular PVCs
```
72
Low Mag has inhibitory effect on NA-K-ATPase which
alters the resting membrane potential
73
How do you replace IV mag?
1-2 g over 5 min with EKG monitoring
| followed by a continuous IV infusion of 1-2g/hr
74
causes of hypermag
```
Iatrogenic administration
Preeclampsia
Antacids/laxatives
Renal failure
Adrenal insufficiency
```
75
what S/S at each mag level
4-7
10
10-15
4-7 = drowsiness, decreased deep tendon reflexes, weakness
10 = respiratory depression
10-15 = respiratory paralysis, coma
15-20 = cardiac arrest
76
What do you use as an antagonist in urgent hypermag situations (bradycardia, heart block, Resp depression)
Calcium
77
Mag will potentiate _______, but not enough to clinically effect us
NDNMBs
78
Where is the majority of calcium found
99% in bones
| 1% in plasma and body cells
79
What is the second messenger that couples cell membrane receptors to cellular responses
Calcium
Muscle contraction, hormones, neurotransmitters, coagulation, myocardial contractility
80
PTH move ca -
CalcitonIN moves Ca
out of bones
INto the bones
81
Causes of hypocalcemia
Hypoparathyroidism
Malignancy
Chronic renal insufficiency
82
How does hyperventilation effect calcium
Hyperventilation leads to alkalosis which facilitates protein-binding of Ca
83
Why do you give Ca when doing large blood transfusions
Citrate in banked blood binds Ca
84
Neuro S/S of hypocalcemia
```
Cramps
Weakness
Chvostek sign
Trousseau sign
Seizure
Numbness
tingling
```
85
CV S/S of hypocalcemia
```
Dysrhythmias
Prolonged QT interval
T-wave inversion
Hypotension
Decreased myocardial contractility
```
86
Pulmonary S/S of hypocalcemia
Laryngospasm
Bronchospasm
Hypoventilation
87
How to correct low Ca levels
Infusion of Ca Chloride (best option, more rapid correction)
```
Ca gluconate (slower)
3g Ca gluconate = 1 g Ca Chloride
```
88
Causes of hypercalcemia
Hyperparathyroidism (>50% cause)
Tumors/malignancy
Calcium mobilization from bone due to immobility
89
CV S/S of hypercalcemia
Hypertension
Heart block
Shortened QT interval
Dysrhythmias
90
Neuromuscular S/S of hypercalcemia
Muscle weakness
Decreased deep tendon reflexes
Sedation
91
Treatment of hypercalcemia
treat underlying cause
give adequate fluids/loop diuetics
If hypercalcemia with life threatening dysrhythmias = emergent dialysis
