fluid + electrolyte balance Flashcards

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1
Q

three fluid compartments of the body

A
  1. intravascular (fluid in blood vessels)
  2. intracellular (fluid in cells, most body fluid is here)
  3. extracellular (interstitial fluid between cells - blood, lymph bone, connective tissue, water, transcellular fluid)
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2
Q

what is it?

third-spacing

A

extracellular fluid is trapped in a body space (pericardial, abdominal, peritoneal, joint cavity, bowel, abdomen, soft tissues) from trauma or burns

trapped fluid is a volume loss + unavailable for normal physiological processes

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3
Q

what is it and what causes it?

edema

A

accumulation of fluid in interstitial space from alterations in oncotic pressure, hydrostatic pressure, capillary permeablility, or lymphatic obstruction

  • localized is from trauma (accident, surgery, local inflammatory process, burns)
  • generalized is from cardiac + renal conditions or liver failure
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4
Q

what are the processes that move fluid?

body fluid transport

A
  • diffusion: solute/dissolved substance moves from high to low concentration
  • osmosis/osmotic pressure: solvent moves from low to high concentration
  • filtration: movement of solutes and solvents from high to low pressure
  • hydrostatic pressure: force exerted by weight of solution
  • osmolalility/osmotic pressure: number of osmotically active particles, concentration of solution (plasma is 275-295 mOsm/kg)
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5
Q

solution types

high, equal, low concentrations

A
  • isotonic : equal concentration on both sides of membrane
  • hypotonic : lower osmolality than body fluids - hypotonic to cells
  • hypertonic : higher osmolality than body fluids)
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6
Q

what is it?

active transport

A

movement of molecules or ions against concentration

substances transported actively: sodium, potassium, calcium, iron, hydrogen, amino acids

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7
Q

sources of fluid intake

A

ingested liquid, foods, water formed by oxidation of foods

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8
Q

sources of fluid loss

A

skin, expired air from lungs, kidneys, GI tract

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9
Q

isotonic dehydration

A

water loss = electrolyte loss (hypovolemia)

decreased blood volume and perfusion
caused by:
* not enough intake
* fluid shift
* excessive loss of isotonic body fluids

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10
Q

hypertonic dehydration

A

more water is lost than electrolytes, water moves out of cells into plasma (makes cells shrink)

caused by:
- too much sweating
- hyperventilation
- ketoacidosis
- prolonged fevers
- diarrhea
- early kidney disease
- diabetes insipidus

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11
Q

hypotonic dehydration

A

more electrolytes lost than water, water moves into cells (makes cells swell)

caused by:
- chronic illness
- excessive fluid replacement
- kidney disease
- chronic malnutrition

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12
Q

isotonic overhydration

A

too much isotonic fluid in extracellular space, hypervolemia or circulatory overload

caused by:
- IV therapy
- kidney disease
- long term corticosteroid therapy

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13
Q

hypertonic overhydration

A

too much sodium

caused by:
- excessive sodium intake
- hypertonic saline
- excessive sodium bicarb

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14
Q

hypotonic overhydration

A

water intoxication, all fluid compartments expand and electrolytes dilute

caused by:
- early kidney disease
- heart failure
- syndrome of inappropriate ADH secretion
- replacing isotonic fluid loss with hypotonic fluids
- irrigation of wounds and body cavities with hypertonic fluids

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15
Q

function + how it’s regulated

potassium

A
  • fluid balance (main ICF ion)
  • acid-base balance
  • nerve impulse transmission (maintains resting membrane potential)
  • maintains normal cardiac rhythms
  • muscle contraction

~ mostly regulated by kidneys

normal = 3.5 - 5.0 mmol/L

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16
Q

causes + interventions

hypokalemia

A

causes:
* meds (diuretics, corticosteroids, albuterol)
* too much aldosterone
* vomiting/diarrhea
* wound drainage (mostly GI)
* prolonged NG suction
* excessive sweating
* kidney disease (can’t reabsorb)
* fasting/NPO
* potassium movement into cells (alkalosis, hyperinsulinism)

interventions:
* supplements (oral can cause nausea/vomiting on empty stomach)
* IV administration (can cause phlebitis)

17
Q

causes + interventions

hyperkalemia

A

causes:
* excessive intake
* potassium-sparing (retaining) diuretics
* kidney disease
* adrenal insufficiency
* movement of potassium out of cells (tissue damage, acidosis, hyperuricemia, hypercatabolism)

interventions:
* potassium-excreting diuretics (if renal function is good)
* if renal function impaired - give sodium polystyrene sulfonate (promotes GI absorption of sodium and potassium excretion)
* if K+ is critically high - IV calcium (to avert myocardial excitability) or dialysis
* hypertonic glucose with insulin to move potassium into cells

pseudohyperkalemia can occur due to methods of blood collection and cell lysis, new specimen would be needed

18
Q

function + regulation

sodium

A
  • water balance (regulates the ECF osmotic forces/blood pressure)
  • nerve impulse conduction
  • acid-base balance

~ regulated by aldosterone (promotes sodium/water reabsorption + potassium excretion)

normal = 135 - 145 mmol/L, accounts for 90% of ECF cations

19
Q

causes + interventions

hyponatremia

A

causes:
* increased excretion (excessive sweating, diuretics, vomiting/diarrhea, wound drainage, kidney disease, low aldosterone)
* not enough intake (NPO, fasting, low-salt)
* dilution of serum sodium (excessive ingestion or irrigation with hypotonic fluids, freshwater drowning, syndrome of inappropriate antidiuretic hormone secretion, hyperglycemia, heart failure)

interventions:
* IV sodium chloride
* osmotic diuretics for water excess
* monitor neuro status for osmotic demyelination if hyponatremia is corrected too fast

20
Q

causes + interventions

hypernatremia

A

causes:
* decreased sodium excretion (corticosteroids, Cushing’s, kidney disease, hyperaldosteronism)
* increased intake
* not enough water (NPO, fasting)
* increased water loss (increased metabolism, fever, hyperventilation, infection, too much sweating, diarrhea, diabetes inspidus)

21
Q

function + regulation

calcium

A
  • bone/tooth formation
  • blood clotting cofactor
  • nerve impulses
  • muscle contraction

~ regulated by parathyroid hormone, vitamin D, calcitonin (act together to control calcium absorption/excretion)

normal serum: 2.25 - 2.75 mmol/L

22
Q

causes + interventions

hypocalcemia

A

caused by:
* GI tract can’t absorb (lactose intolerance, celiac, Crohn’s, lack of vitamin D, end-stage kidney disease)
* increased excretion (kidney disease, diarrhea, wound drainage)
* conditions that decrease ionized fraction of calcium (hyperproteinemia, alkalosis, calcium binders, pancreatitis, hyperphosphatemia, parathyroid gland removal)

interventions:
* supplements
* aluminum hydroxide (reduces phosphorus = countereffect of increasing calcium)
* vitamin D helps intestines absorb calcium

23
Q

causes + interventions

hypercalcemia

A

caused by:
* too much calcium/vitamin D intake
* decreased excretion (kidney disease, thiazide diuretics)
* increased bone resorption (hyperparathyroidism, hyperthyroidism, malignancy that destroys bone, immobility)

interventions:
* diuretics to increase calcium excretion
* medications that stop calcium resorption from bone (phosphorus, calcitonin, biphosphonates, prostaglandin synthesis inhibitors)
* monitor for fracture, urinary stones

24
Q

function + regulation

magnesium

A
  • cofactor for many enzymes
  • nerve impulse transmission
  • muscle contraction

~ absorbed by intestines + eliminated by kidneys

normal: 0.74 - 1.07 mmol/L

25
Q

causes + interventions

hypomagnesemia

A

caused by:
* not enough intake (vomiting, diarrhea, celiac, Crohn’s)
* increased excretion (diuretics, chronic alcohholism)
* intracellular movement (hyperglycemia, insulin, sepsis)

interventions:
* magnesium sulfate IV (oral can cause diarrha)

26
Q

causes + interventions

hypermagnesemia

A

caused by:
* increased intake (antacids/laxatives containing magnesium)
* renal insufficiency

interventions:
* calcium gluconate IV (antidote for Mg overdose)
* calcium chloride
* diuretics

27
Q

function + regulation

phosphate

A
  • bone formation
  • muscle contraction (provides energy as ATP)
  • acid-base balance

~ regulated by parathyroid hormone, vitamin D, calcitonin (act together to control absorption/excretion)

normal: 0.97 - 1.45 mmol/L

28
Q

causes + interventions

hypophosphatemia

A

caused by:
* malnutrition/starvation
* increased excretion (hyperparathyroidism, malignancy, magnesium/aluminum hydroxide based anatacid)
* intracellular shift (hyperglycemia, respiratory alkalosis)

interventions:
* phophorus supplement with vit D
* phosphorus IV

29
Q

causes + interventions

hyperphosphatemia

A

caused by:
* decreased renal excretion
* tumor lysis syndrome
* increased intake
* hypoparathyroidism

interventions:
* phosphate-binding meds to increase excretion