Topic 6: Fluid Balance Flashcards
where is fluid distributed in the body
fluid surrounds all cells in the body and is also inside cells
what are the characteristics of body fluids
-fluid amount (volume)
-concentration (osmolality)
-composition (electrolyte concentration)
-degree of acidity (pH)
what is the recommended fluid intake
~2300mL/day
when is the thirst mechanism in the hypothalamus activated?
when plasma osmolarity increases (osmoreceptor-mediated thirst) or the blood volume decreases (baroreceptor-mediated thirst and angiotensin II and III mediated thirst)
fluid distribution
the movement of fluid among its various compartments
extracellular and intracellular distribution occurs by
osmosis
vascular and interstitial distribution occurs
filtration
where does fluid ouput normally happen in the body
skin, lungs, GI tract, kidneys
insensible loss
Water lost thru the skin (individual is unaware of losing that water)
sensible loss
loss that is perceived or is measurable. (wound drainage, GI tract, urine)
fluid output is influenced by what hormonal influences
-ADH
-RAAS
-ANPs
When is ADH released?
when dehydrated and and body fluids are more concentrated
what factors increase ADH levels
o Decreased blood volume (dehydration, hemorrhage)
o Pain
o Stressors
o Some medications
what does the RAAS regulate
ECF volume by influencing how much sodium and water are excreted in urine.
it also contributes to regulation of BP
Atrial natriuretic peptides (ANPs)
regulates ECF volume by influencing how much sodium and water is excreted in urine
-Cells in the atria of the heart release ANP when they are stretched (e.g., by an increased ECV).
Volume imbalances
disturbances of the amount of fluid in the extracellular compartment
osmolarity imbalances
disturbances of the concentration of body fluids
When is ECV deficit present?
when isotonic fluid is insufficient in the extracellular compartment.
(With ECV deficit, output of isotonic fluid exceeds intake of sodium-containing fluid.)
When is ECV excess present?
occurs when too much isotonic fluid is found in the extracellular compartment.
(when you eat more salty foods than usual and drink water, ankles or feet may swell)
hypertonic
Water leaves cells by osmosis, and they shrivel (more solutes outside cell)
hypotonic
-The excessively dilute condition of interstitial fluid causes water to enter cells by osmosis, causing the cells to swell (more solute in cell)
hypernatremia
“water deficit”; hypertonic
loss of more water than salt or gain of salt
what are the s/s of hypernatremia
cerebral dysfunction (which arise when brain cells shrivel)
hyponatremia
“water excess/water intoxification”; hypotonic
(more water than salt or less salt than water)
what are the s/s of hyponatremia
cerebral dysfunction (occur when brain cells swell)
clinical dehydration
ECV deficit and hypernatremia often occur at the same time
what are some common causes of clinical dehydration
gastroenteritis or other causes of severe vomiting and diarrhea when people are not able to replace their fluid output with enough intake of dilute sodium-containing fluids.
hypokalemia
abnormally low potassium concentration in the blood.
hyperkalemia
abnormally high potassium concentration in the blood
Hypercalcemia
abnormally high calcium concentration in the blood
Hypomagnesemia
abnormally low magnesium concentration in the blood
Hypermagnesemia
abnormally high magnesium concentration in the blood
potassium function
Maintains resting membrane potential of skeletal, smooth, and cardiac muscle, allowing normal muscle function
who are those at the greatest risk for hyperkalemia
-Chronically ill patients
-Debilitated patients
-Older adult
-Patients who have oliguria (decreased UO)
what are s/s of hyperkalemia
o Bilateral muscle weakness in quadriceps
o Transient abdominal cramps
o Diarrhea
o Dysrhythmias
o Cardiac arrest if severe
hypokalemia causes
o Decreased potassium intake and absorption, a shift of potassium from the ECF into cells, and an increased potassium output
o Increased potassium output include diarrhea, repeated vomiting, and use of potassium-wasting diuretics
hypokalemia s/s
o Bilateral muscle weakness that begins in quadriceps and may ascend to respiratory muscles, abdominal distention, decreased bowel sounds, constipation, dysrhythmias
calcium function
Influences excitability of nerve and muscle cells; necessary for muscle contraction
hypercalcemia causes
o Increased calcium intake and absorption
o Shift of calcium from bones into the ECF
o Decreased calcium output
hypercalcemia s/s
o Anorexia, nausea and vomiting, constipation, fatigue, diminished reflexes, lethargy, decreased level of consciousness, confusion, personality change, cardiac arrest if severe
hypocalcemia causes
o Decrease absorption of dietary calcium and also increases calcium output by preventing resorption of calcium contained in GI fluid
o People who have acute pancreatitis frequently develop hypocalcemia because calcium binds to undigested fat in their feces and is excreted.
hypocalcemia s/s
o Numbness and tingling of fingers, toes, and circumoral (around mouth) region, positive Chvostek’s sign (contraction of facial muscles when facial nerve is tapped), hyperactive reflexes, muscle twitching and cramping; carpal and pedal spasms, tetany, seizures, laryngospasm, dysrhythmias
magnesium functions
o Influences function of neuromuscular junctions; is a cofactor for numerous enzymes
hypermagnesemia causes
o Renal failure
o Diabetes Mellitus
o Clients who ingest large amounts of Mg-containing antacids such as Tums, Maalox, Mylanta, or laxatives such as MOM are also in ↑ risk for developing hypermagnesemia
hypermagnesemia s/s
o Bradycardia and hypotension
o Severe hypermagnesemia: cardiac arrest
o Drowsy or lethargic
o Coma
o Deep tendon reflexes are reduced or absent
o Skeletal muscle contractions become progressively weaker and finally stop
hypomagnesemia causes
o Decreased magnesium intake and absorption
o Shift of plasma magnesium to its inactive bound form
o Increased magnesium output
hypomagnesemia s/s
o Positive Chvostek’s sign, hyperactive deep tendon reflexes, muscle cramps and twitching, grimacing, dysphagia, tetany, seizures, insomnia, tachycardia, hypertension, dysrhythmias
Chronic alcohol abuse commonly causes…
hypomagnesemia, in part because it increases renal magnesium excretion
what things in medical history are important to asses for fluid output
-recent surgery (excessive blood loss)
-GI output
-trauma (respiratory disorder, burns (increased exudate output) hemorrhage
oliguria
Decreased urine output
what is the most accurate indicator of fluid status?
daily weights
each 2.2 lbs of weight gained or lost overnight is equal to _____
1 L of fluid retained or lost
When taking daily weights it is impprtant to
use the same conditions (clothes, weight, scale, sheets etc)
fluid intake and output
compare intake vs output
if intake is substantially greater than output…
The patient may be gaining excessive fluid or may be returning to normal fluid status by replacing fluid lost previously from the body.
if intake is substantially smaller than output…
The patient may be losing needed fluid from the body and developing ECV deficit and/or hypernatremia or may be returning to normal fluid status by excreting excessive fluid gained previously.
Intake includes what?
all liquids eaten, drunk, or received through IV, NG tube
output includes what?
Urine, diarrhea, vomitus, gastric suction, wound drainage, or other tubes
health promotion and fluid balance
o Fluid replacement education
o Teach patients with chronic conditions about risk factors and signs and symptoms of imbalances.
total parenteral nutrition
administered to patients who cannot, or should not, get their nutrition through eating
crystalloids
electrolyte therapy
colloids
Blood and blood components.
what is the goal of IV fluid administration
to correct or prevent fluid and electrolyte disturbances. IVs allow direct access to the vascular system, permitting continuous infusion of fluids over a period of time.
Isotonic solutions
have the same effective osmolality as body fluids. (normal saline)
what is normal saline used for
ECV replacement to prevent or treat ECV deficit.
Hypotonic solutions
have an effective osmolality less than body fluids, thus decreasing osmolality by diluting body fluids and moving water into cells.
*make body fluid less concentrated, forcing water into cells
Hypertonic solutions
have an effective osmolality greater than body fluids. If they are hypertonic sodium-containing solutions, they increase osmolality rapidly and pull water out of cells, causing them to shrivel.
Central catheters and implanted ports
Devices for long-term use, which empty into a central vein.
Central catheters and implanted ports
Devices for long-term use, which empty into a central vein.
Peripherally inserted central catheters (PICC lines)
enter a peripheral arm vein and extend through the venous system to the superior vena cava, where they terminate.
