Fluid Balance Flashcards
Homeostasis
how the body works to keep itself balanced
negative feedback
the body bringing itself back to normal
ie blood sugar goes up, insulin goes up, sugar goes down
positive feedback
causes further instability, like temperature going up when someone is hot instead of down
feed forward regulation
anticipatroy ques, like the body pumping the heart rate becuase it knows its going to be running
who is the most susceptible for fluid imbalances
the elderly, the very young, preoperative pateints
why are babies at risk for fluid imbalnaces
they have more water content than an adult (75%), have different skin, and cannot function independently when getting water
why are the elderly at risk for fluid imbalances
less water content-55%, they are already at a disadvantage if they lose water, less lean body mass
Decreased thirst mechanisms
increased drug/drug interaction
why are preoperative patients at risk for fluid imbalances
restrictions, blood/fluid loss, surgery stress
what is the best measure of water loss
body weight
intracellular fluid compartments
inside cells, holds about 2/3rd of body water and 40% of body weight
extracellular fluid compartments
area outside cells- like vascular space or interstitial space
20% of body weight
Interstitial space
where cells ar flowing, the 3rd space
difference between interstitial and plasma fluid
nearly identical, plasma just has more protein
electrolytes def
substances whose molecules split into iones when placed in water
ion: electrically charged
cations: positively charged
anions: negatively charged
ECF primary electrolyte
sodium
ICf primary electrolyte
potassium
Simple diffusion
particles become widely dispesed and reach union concentration
moving from areas of high concentration to lower until net flux is equal
facilitated diffusion
moving of bigger things that may need a transport protein, like glucose needing insulin
Does not require ATP
Active Transport
uses ATP to move molecule against a concentration gradient, from low to high concentration
like sodium potassium pump
what is hydrostatic pressure
the pressure pushing water out of the cell, against the capillary
the BP generated by heart contraction
Oncotic pressure
pressure that keeps thing in the cell
capillary hydrostatic pressure
movesd water out of the capillaries
plasma oncotic pressure
moves fluid into the capillaries
interstitial hydrostatic pressure
moves fluid out of interstitial space
interstitial oncotic pressurew
moves water out of the capillaries
hydrostatic/ oncotic pressure on vascular system
in atrial end capillary hydrostatic pressure exceed oncotic pressures so fluid can move into tissue
when it gets to the venous end, oncotic pressure exceed oncotic pressure so fluid flows back into capillary
what can happen with an increase in venous hydrostatic pressure
edema- inhibits fluid movement back in the capillary
fluid overload, heart failure, liver failure, other venous problems
Osmosis
across a semipermeable water will go to the area with higer concretation
osmotic pressure
amount of pressure required to stop osmotic flow of water
osmolarity
comes from plasma in vascular space
millimoles/L of solution
osmalality
measure the number of milliosmoles/kg of water
what does osmalitly over 295 mean
there is greater particles and less water, they are dehydrated and
fluid surrounding cells is hypertonic
what does osmolality of less than 275 mean
more, less particles
fluid overload
fluid surrounding cells is hypotonic
hypertonic
fluid with more concentrated solutes than within
will cause cell to shrink as fluid will travel to area with more concentrate
hypotonic
solution in which their is less solute concentration than inside the cells
will cause cells to swell as fluid flows to area of higher concentration, inside the cell
isotonic fluid
balanced fluid, will cause fluid shift
first spacing
normal distribution of fluid in ICF and ECF compartment
second spacing
abnormal accumulation of interstitial fluid
third spacing
excess fluid collects in nonfunctional area between cells
causes ascites, edema
insensible water loss
invisible vaporization from lungs and skin
is only water loss
regulates body temp
sensible
excess sweating
w/ fever, excercise, high temps
loss of water and electrolytes
If a patient has greatly increased capillary hydrostatic pressure that exceeds the pressure exerted by capillary colloid osmotic pressure, where will the fluid move into?
interstitial space
The interstitial space. Hydrostatic pressure pushes fluid out of vascular space, osmotic pressure pulls fluid into vessels. If hydro > osmotic = fluid pushed out into interstitial space.
The health care provider orders an I.V. solution of 5% dextrose in 0.45% (D5.45) sodium chloride solution for a post-operative patient. What category of fluid is this solution?
Hypertonic
When a patient is under stress, they retain fluid. Therefore we give hypertonic fluid to shift fluids out of the cells and into the vascular space so it can be excreted through the kidneys.
During administration of a hypertonic IV fluid solution, the mechanism involved in equalizing the fluid concentration between ECF and the cells is
osmosis
While osmosis and diffusion is similar, diffusion is the movement of particles to create a union concentration, osmosis is the movement of water to reach the union concentration.
Dextrose 5% in 0.45% NaCl (D5.45)
Hypertonic
0.9% NaCl
Isotonic
Dextrose 5% in Water (D5W)
Hypotonic
0.45% NaCl
Hypotonic
Lactated Ringer’s (LR)
Isotonic
Dextrose 5% in 0.9% NaCl (D5.9)
Hypertonic
3% sodium
Hypertonic
Dextrose 5% in Lactated Ringer’s (D5LR)
Hypertonic
How does the hypothalamus regulate fluid balance
works as the thirst center: BOfy fluit deficcit or an increase in plasma osmlality activateds receptors in the hypothalamus that stimulate thirst and release of ADH from posterior pituitary gland
How does ADH work with fluid balance
acts on distaal tubules of kidney sby making them more water permeable, allowing increased water reabsorption from tubular filtrate into the blood and decreased excretion into the urine
What factors infleunce ADH secretion/thirst
decreased BP, nausea, pain, hypoglycemia, hypoxemia stimulate ADH release
effect of surgery on ADH
stress response, analgesics, anathesia ewual ADH release and decreased osmolality
aldosterone with fluid balance
holds on too sodium, allows retaining of fluid
released by adrenal cortex
REnal fluid balance regulation
helps maintain normal plasma osmolality, electrolyte balance, blood volume, and acid-base balance
if impaired: edema, potassium/phosphate retention, acidosis, electrolyte imbalances
ANP/ BNP
atrial natriuretic peptide and B-type natriuretic peptide
Cardia peptides, promote excretion of Sodium and water, decreasing BLood volume/BP
Cardiac system with fluid balance
increased atrial pressure= high serum sodium levels= increase ANP/BNP to allows water to be gotten rid of
why with heart disease/kidney failure, water retention
GI Regulation of Fluid balance
Intake/output
Diarrhea, vomiting preventing GI reabsorption of secreted fluid cna cause significant fluid/electrolyte loss
Lymphatic system regulation of fluid balance
normally drain of excess fluid at ends of venous capillaries, but if removed fluid not drained as easily
what does the body do when dehydrated
you are hyperosmolar
pituitary stimulates antidiuretic to hold on to flui and lower plasma osmolality
REnal perfusion decreases and hormones renin, angiotensin and aldosterone stimulate/increased
Extracellular Fluid volume deficit (ECFVD)
Dehydration, loss of fluid from vascular space
what can cause extracellular fluid volume deficit
Diabetes insipidus, vomiting/diarrhea, NG suction, diuretics, hemorrhage, hyperglycemia/ ketoacidosis, osmotic diuresis, insensible water losses like fever, heatstroke, burns
Manifestations of ECFVD
sluggish cap refill, dry mucus membranes, skin tenting, orthostatics, thready pulse, tachycardia, decreased blood pressure, weight loss, tried, dizzy, lightheaded, constipation, increased respiratory rates, decreased urine output with more concentrated urine
Labs with ECFVD
osmolality above 295
plasma sodium above 145
blood urea nitrogen above 25
hematocrit above 55
urine specific gravity above 1.030
ECFVD intervention
I/Os, daily weights, ORtho BP
LAbs: BUN/CR, HRt, urine specific gravity
Fluid per md order: Oral or IV
REduce risk of falls, skin integrity problems
What fluid are good bad for PO rehydration
good: water, decaf herbal teas
Bad: Coffee, any caffeine, sugary sodas
Isotonic fluids used for
Filling vascular space, like .9 normal saline, lactated ringers
Give first with dehydration+low BP
Hypotonic fluid used for
shifting from vascular space into cells
.45, D5W (IV tap water)
Lower BP, so use after Iso fluids w/ severe dehydration
Hypertonic fluid used for
Shifting water from cells to vascular space
Dehydrating cells with fluid overload/excess
D545
What fluid should be used with ECFVD
Isotonic first to fill vascular space and increase BP, then hypotonic to shift fluid into cells
Intracellular fluid volume deficit (ICFVD)
Cells shrink
Rare, but may be in older adults with acute water loss
hyperosmolar in vascular space, water is pulled from the cells
Manifestations of ICFVD
Thirst, oliguria, CNS changes from effect on neural cells
ICFVD management/intervention
hypotonic fluid to push fluid back into cells if BP is ok
address underlying cause
Extracellular fluid volume excess: intravascular hypervolermia
Fluid overload, failure to excrete, increased total body sodium
increased hydrostatic pressure and decreased oncotic pressure
causes of ECFVE (intravascular)
long term corticosteroid use
cushing syndrome
heart/renal disease/failure
primary polydipsia
SIADH- syndrome of inappropriate antidiuretic hormone secretion
stress
organ failure
Manifestations of ECFVE (intravascular)
Bounding pulse, increased BP, pulmonary and peripheral overload crackles, edema
Bloated, swollen, SOB, fatigue
low urine output, pale cold extremities
Lab indicators of ECFVE
Osmolality < 275
sodium <135
hematocrit < 45%
specific gravity of urine < 1.010
blood urea nitrogen <8
ECFVE intervention/management
Monitoring skin, daily wieghts, I/Os, fluid restriction
Oxygenation and monitoring of crackles
Elevate legs and mobilize fluid
Promote Urinary w/ diuretic like furosemide, HCTZ, Spironolactone
K-wasting diuretics
Increase urination and potassium loss, Furosemide, HCTZ
k-sparing diuretics
increase urination without promoting potassium loss
spironolactone
ECFVE: third spacing
tissue injury or protein malnutrition leading to fluid shift
increasedf cap permeability, decreased serum protein/albumin levels
obstrcted lymphatic pressure
increased capillary hydrostatic pressure
ECFVE 3rd manifestations
Weak pulse, hypotension, pallor, oliguria, Decreased LOc, elevated BUN, hematocrit, urine specfic gravity, edema, ascites
ECFVE 3rd management/interventions
weight, vitals I/os, skin intergity
interstitial to vascular with hypertonic, diuretics to get it out
Intracellular fluid volume excess (ICFVE
Water intoxication
water excess or solute deficit
can cause brain cell swelling
intracellular shift of water soward sodium inside cells
ICFVE manifestations
increased intracranial pressure, altered LOC
hemodilution: plasma sodium< 125, decreased hematocrit
ICFVE management/interventions
safety (ie seizure, fall risk) fluid restriction, sodium administration, intervention to prevent further increase in ICP ( stool softeners, antiemetics)
The patient is admitted to a nursing unit from a long-term care facility with a hematocrit of 58% and a serum sodium level of 152mEq/L. Which condition is a cause for these findings?
Dehydration
Dehydration = hemoconcentration. More solutes and less fluid would manifest in elevated hematocrit and sodium levels.
A patient is admitted with shortness of breath, bibasilar crackles on auscultation, and the B/P is 150/90 mmHg. The nurse suspects fluid volume overload. Which laboratory result would be consistent with this nursing diagnosis?
Serum osmolality - 320 mOsm/L
Blood urea nitrogen (BUN) – 32
Serum sodium - 130 mEq/L
Serum potassium – 4.0 mEq/L
Serum sodium
Fluid excess = hemodilution. Less solutes and more fluid would manifest in decreased sodium levels.
A patient comes to the clinic reporting frequent, watery stools and dizziness for the past 2 days. Which action should the nurse take first?
Obtain baseline weight
Check the patient’s blood pressure
Draw blood to check serum electrolyte levels
Ask about extremity numbness and tingling
Check blood pressure
Patient is at risk for dehydration and is exhibiting signs of fluid deficiency (dizziness). Always assess first, and vitals are vital! In this case, dizziness comes from loss of fluid which leads to vascular depletion and low BP.
