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NUR370 Pathophysiology and Pharmacology > Fluids and Electrolytes > Flashcards

Fluids and Electrolytes Flashcards

1
Q

Intracellular Fluid (ICF)

A
  • fluid inside cells
  • 2/3 of body fluid
  • primarily located in skeletal muscle mass
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2
Q

Extracellular Fluid (ECF)

A
  • fluid outside cells
  • 1/3 of body fluid
  • transport system that carries nutrients and waste to and from cells

3 compartments:

  • interstitial
  • intravascular
  • transcellular (synovial fluid, CSF, pleural and peritoneal fluid)
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3
Q

Osmolarity

A

concentration of particles (solutes) dissolved in a solution (solvents)
measure for evaluating concentration of plasma, urine and body fluids

*plasma osmolarity is usually between 280 and 300 mmol/kg

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4
Q

Tonicity

A

the ability of an extracellular solution to make water move into and out of a cell by osmosis
- related to its osmotic concentration (osmolarity)

a. solution with LOW osmotic concentration has FEWER solute particles per litre = LOWER TONICITY
b. solution with HIGH osmotic concentration has MORE solute particles per litre = HIGH TONICITY

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5
Q

Osmosis

A

movement of water between two compartment separated by semipermeable membrane

water moves from areas of low solute concentration to areas of high solute concentration

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6
Q

Hypertonic IV Fluid

A

fluid leaves cells

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7
Q

Hypotonic IV Fluid

A

fluid goes into cells

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8
Q

Isotonic IV Fluid

A

no osmosis, not moving in or out

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9
Q

Hydrostatic pressure

A
  • force within a fluid compartment

- major force that pushes water out of the vascular system at the capillary level

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10
Q

Oncotic pressure

A
  • colloid osmotic pressure
  • osmotic pressure exerted by protein, such as albumin, to pull water into circulatory system

*albumin accounts for 70% of oncotic pressure

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11
Q

Filtration

A

fluid moves out of the capillary into the interstitial space

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12
Q

Reabsorption

A

fluid moves back into capillary from the interstitial space

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13
Q

Net filtration

A

Starling hypothesis

Forces favouring filtration

a. capillary hydrostatic pressure (blood pressure)
b. interstitial oncotic pressure (water pulling)

Forces opposing filtration

c. plasma oncotic pressure (water pulling)
d. interstitial hydrostatic pressure

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14
Q

Albumin and oncotic pressure

A

when albumin levels are too low, water leaves vasculature and going into interstitial space
= edema, swelling!

albumin is manufactured by the liver

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15
Q

Causes of edema

A
  1. increased capillary permeability
    - burns, inflammation
  2. changes in plasma protein level
    - cirrhosis, malnutrition, kidney disease causing loss of plasma protein
  3. increased capillary hydrostatic pressure
    - salt and water retention, heart failure

*lymphatic system usually absorbs fluids but if lymph system is blocked, fluid gets stuck

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16
Q

Third spacing

A

fluid accumulation in part of the body where it is not easily exchanged with ECF
increased permeability causes protein to leak out, which then pulls water out as well

i.e. patient with severe infection

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17
Q

S/S of Third Spacing

A

a. decreased urine output
b. increased HR
c. decreased BP
d. increased weight
e. edema, ascites

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18
Q

Hypothalamic-pituitary Regulation

A

osmoreceptors in hypothalamus sense fluid deficit or excess

  • fluid excess&raquo_space; secretion of ADH is suppressed at posterior pituitary&raquo_space; urinary excretion of water
  • fluid deficit&raquo_space; secretion of ADH is increased&raquo_space; water reabsorption

**Fluid Deficit: hypothalamus stimulates thirst and ADH release

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19
Q

Adrenal Cortical Regulation

A

Fluid Deficit: hypothalamus signals anterior pituitary to secrete ACTH, which then signals

adrenal cortex to secrete

a. cortisol
b. aldosterone

which increases Na+ reabsorption and K+ excretion

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20
Q

Renal regulation

A

primary organ for regulating fluid and electrolyte balance

adjust urine volume by:

a. selective reabsorption of water and electrolytes
b. renal tubules are sites of action of ADH and aldosterone

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21
Q

Cardiac regulation

A

Natriuretic peptides are antagonists to the RAAS
- produced by cardiomyocytes in response to increased atrial pressure

**natriuretic peptides suppress secretion of aldosterone, renin, and ADH to decrease blood volume and pressure

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22
Q

Gastrointestinal regulation

A

INPUT
- oral intake

OUTPUT

  • feces
  • diarrhea and vomiting

*can lead to significant fluid and electrolyte loss

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23
Q

Insensible water loss

A

invisible vaporization from lungs and skin to regulate body temperature

  • approximately 600 to 900ml/day
  • no electrolytes are lost
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24
Q

Age related considerations

A

a. structural changes in kidney
b. hormonal changes
c. loss of subcutaneous tissue
d. reduced thirst mechanism

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25
Water content across lifespan
Infant: 70-80% water Adult: 50-60% water Older Adult: 45-55& most water are stored in muscle tissue! *more fat = less water!
26
Hypovolemia
ECF volume deficit - decrease capillary hydrostatic pressure and fluid transport 3 Main Causes: 1. fluid loss 2. reduced fluid intake 3. fluid shift from intravascular space
27
How does the body respond to hypovolemia?
a. decreased renal blood flow triggers RAAS leading to increased ADH and aldosterone production b. thirst response c. increase in heart rate and vascular resistance **When body cannot compensate anymore, hypovolemic shock occurs
28
S/S of Hypovolemia
- hypotension - tachycardia, weakened pulse - thirst - flattened neck veins - dry mucous membrane/skin, decreased skin turgor - weight loss - decreased urine output - prolonged capillary refill - sunken eyes - confusion, headache, changes in LOC
29
Hypovolemia Assessment
a. intake and output b. cardiovascular changes (HR, BP) c. respiratory changes d. daily weights e. skin assessment f. neurological function - LOC, PERRLA, voluntary movement, muscle strength, reflexes
30
Treatment for Hypovolemia
a. oral or parenteral fluids b. fluid resuscitation (IV infusion) c. blood/blood product if hemorrhage d. antidiarrheals/antiemetics as needed *urine output is a good indicator of fluid volume returning
31
Why are infants more predisposed to serious, rapid fluid volume deficits?
- surface area to volume - 3 times greater than adults - ability to concentrate urine - metabolic rate
32
Hypervolemia
fluid volume excess - abnormal increase in volume circulating fluid 3 Main Causes: 1. risk for sodium and water retention 2. excessive sodium and water intake 3. fluid shifts to the intravascular space
33
How does the body respond to Hypervolemia?
a. circulatory overload b. increased cardiac contractility and increased bp c. increased capillary hydrostatic pressure d. shift of fluid into interstitial space e. edema f. increased bp inhibits ADH and aldosterone, which increases urinary elimination **If hypervolemia is severe, CV dysfunction, heart failure and pulmonary edema may develop
34
S/S of Hypervolemia
- hypertension - tachypnea, dyspnea and crackles - cyanosis - decreased tissue perfusion - rapid, bounding pulse - headache - distended neck veins - moist skin - weight gain - edema - muscle twitching
35
Hypervolemia Assessment
a. intake and output b. cardiovascular changes (HR, BP) c. respiratory changes d. daily weights e. skin assessment f. neurological function - LOC, PERRLA, movment of extremities, muscle strength, reflexes
36
Treatment for Hypervolemia
a. remove fluid without changing electrolyte composition or osmolarity of ECF b. promote output and treat underlying condition c. restrict sodium and fluid intake d. diuretic therapy - furosemide e. dialysis
37
Electrolytes
substances which split into ions when placed in a solution + cations are positively charged particles - anions are negatively charged particles
38
Prevalent Cations and Anions in ECF and ICF
ECF cation: Na+ anion: Cl- ICF cation: K+ anion: phosphate
39
Sodium Reference Range
135-145 mmol/L
40
Regulation of sodium balance
a. ADH increases water reabsorption in the kidneys, reduces sodium concentration b. aldosterone promotes sodium reabsorption in the distal nephron c. atrial natriuretic hormone (ANH) promotes sodium excretion *changes in serum Na+ may reflect sodium or water imbalance, usually in ECF volume
41
Hypernatremia Critical Value
> 160 mmol/L results from water loss osmotic shift from ICF to ECF >> cellular dehydration
42
S/S of Hypernatremia
a. intense thirst (early symptom) b. agitation, restlessness c. water loss dry swollen tongue, weakness, postural hypotension, decreased central venous pressure, weight loss d. sodium gain flushed skin, weight gain, peripheral and pulmonary edema, increased bp, increased CVP
43
Treatment of Hypernatremia
a. treat underlying cause b. oral fluid or IV solution (D5W or hypotonic 0.45%NS) c. diuretics d. monitor sodium levels
44
Hyponatremia Critical Value
<120 mmol/L results from excess sodium loss or water gain osmotic shift from ECF to ICF >> intracellular edema
45
``` Dilutional Hyponatremia (water intoxication) ```
resulting from large intake of free water or replacement fluid loss with IV D5W water enters into cells, coma results from swelling brain tissues * babies under 6 months * lethal volume around 6L in a 165lb adult
46
S/S of Hyponatremia
Mild: not associated with any symptoms Moderate: lethargy, weakness, confusion, headache, nausea, vomiting, abdominal cramps Severe: muscle twitching, seizure, coma, death
47
Treatment of Hyponatremia
a. treat underlying cause b. replace lost sodium (PO or IV) SLOWLY c. get rid of excess water (loop diuretics) d. if primary water deficit, prevent water loss or water replacements
48
Potassium
- transmission and conduction of nerve and muscle impulses - cellular growth - maintenance of cardiac rhythms - acid-base balance
49
Potassium Reference Range
3.5-5.0 mmol/L
50
Sources of Potassium
- fruits and vegetables - salt substitutes - potassium medications (PO or IV) - stored blood
51
Regulation of Potassium Balance
aldosterone, insulin, epinephrine and alkalosis facilitate K+ into the cells insulin deficiency, aldosterone deficiency, acidosis and strenuous exercise facilitate K+ out of cells *maintained by sodium potassium pump
52
Hyperkalemia Critical Value
> 6.5 mmol/L
53
Causes of Hyperkalemia
a. massive intake b. impaired renal excretion c. shift from ICF to ECF *common in renal failure HYPEREXCITABILITY: more intense action potential >> longer refractory period >> slower movement
54
S/S of Hyperkalemia
Mild: no specific symptoms Moderate: tingling of lips and fingers, restlessness, intestinal cramping and diarrhea, ECG changes Severe: muscle weakness, loss of muscle tone, flaccid paralysis, cardiac arrest - arrhythmia can lead to death
55
ECG changes and Hyperkalemia
5. 5-6.5 mmol/L: tall, peaked T-wave 6. 5-7.5 mmol/L: loss of P wave 7-8 mmol/L: widening of QRS complex 8-10 mmol/L: cardiac arrythmias, sine wave pattern, asystole (beepppp)
56
Treatment of Hyperkalemia
a. telemetry, monitoring b. eliminate oral or parenteral K+ intake c. increase elimination of K+ (diuretics, dialysis, kayexalate) d. force K+ form ECF to ICF by IV insulin e. reverse membrane effects using calcium gluconate IV
57
Hypokalemia Critical Value
< 2.5 mmol/L
58
Causes of Hypokalemia
a. abnormal losses of K+ via kidneys or GI tract b. magnesium deficiency c. metabolic alkalosis
59
S/S of Hypokalemia
Mild: no specific symptoms Moderate: muscle weakness/spasms, fatigue, numbness, tingling, constipation, palpitations Severe: confusion, lethargy, weak pulses, hypotension, muscle cramps and pain, cardiac arrhythmias
60
ECG changes and Hypokalemia
shallow T wave ST depression prominent U wave
61
Treatment of Hypokalemia
a. treat underlying cause b. telemetry, monitoring c. KCl supplements (PO or IV) should not exceed 10-20 mmol/hr

NUR370 Pathophysiology and Pharmacology (20 decks)

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