Fluid & Electrolyte Balance Flashcards
Exam 1
Fluid & electrolyte balance
regulation of body fluid volume, osmolarity, and composition
interstitial fluid
fluid between cells; “third space”
movement of fluid (water) through a cell or blood vessel membrane because of hydrostatic pressure
Filtration
Pressure exerted by water molecules against the surfaces (membranes or walls) of a confining space
Hydrostatic pressure
movement of particles across a semipermeable membrane from an area of higher particle concentration to lower particle concentration
Diffusion
two fluid spaces that have different concentrations of the same type of particles
Concentration gradient
the movement of water only through a selectively permeable membrane to achieve equilibrium of osmolarity
Osmosis
What is the normal osmolarity for plasma and other body fluids?
300 mOsm/L
Hyperosmotic / hypertonic fluids means there is more ____ than _____.
solute; water
Hyposmotic / hypotonic fluids means there is more ____ than _____.
water; solute
Osmoreceptors
cells that respond to changes in ECF
dissolved substances that express an electrical charge
Electrolytes
What are 3 patient populations that are at risk for fluid and electrolyte imbalance?
(1) older adults
(2) CKD or endocrine disorders
(3) taking drugs that alter F&E balance
T/F: All adults who are ill are at some risk for electrolyte imbalances
True
Na Normal Range
136-145 mEq/L
K normal range
3.5-5.0 mEq/L
Ca normal range
9.0-10.5 mg/dL
Cl normal range
98-106 mEq/L
Mg normal range
1.3-2.1 mEq/L
Why are older adults at risk for F&E imbalances?
Age-related organ changes
What factors influence the amount and distribution of body fluids?
(1) age
(2) gender
(3) amount of fat
Why do females tend to have higher dehydration risk than males?
Because males usually have more muscle mass than females, and females have more fat than males. Muscle mass holds more water, while fat holds almost no water.
Name 2 age-related changes in the kidneys that put older adults at risk of F&E imbalance
(1) decreased glomerular filtration
(2) decreased concentrating capacity
Name 3 age-related changes in the skin that put older adults at risk of F&E imbalance
(1) loss of elasticity
(2) decreased turgor
(3) decreased oil production
Name 1 age-related changes in the muscular system that put older adults at risk of F&E imbalance
decreased muscle mass
Name 1 age-related changes in the neurologic system that put older adults at risk of F&E imbalance
Reduced thirst reflex
Name 1 age-related changes in the endocrine system that put older adults at risk of F&E imbalance
Adrenal atrophy
What are the two things that trigger thirst response?
(1) increase in blood osmolarity
(2) decrease in blood volume
What is the most important and sensitive water loss route?
Kidney
the minimum amount of urine output per day needed to excrete toxic waste (definition)
obligatory urine output
What is the obligatory urine output amount?
400-600 mL/day
natural water losses without a mechanism to control it
Insensible water loss
What is the typical amount of insensible water loss per day?
500-1000 mL/day
What puts a pt at increased risk for insensible water loss?
(1) mechanical ventilation
(2) rapid respirations
(3) continuous GI suctioning
What are the most important body fluids to keep in balance for optimal function?
blood, ICF
What triggers RAAS (4)?
(1) low BP
(2) low blood volume
(3) low blood Na
(4) low blood oxygen
Name the 3 main actions of angiotensin II
(1) vasoconstriction & peripheral resistance
(2) lower glomerular filtration rate / lower urine output
(3) triggers secretion of aldosterone
Why is the Na gradient important?
Muscle contraction
Cardiac contraction
nerve impulse transmission
If Na serum levels are low, we inhibit ____ and ____ ; trigger ____
ADH, NP; RAAS
If Na serum levels are high, we inhibit ____ and stimulate ____ and _____.
aldosterone; ADH, NP
Why is the K gradient important?
generation of action potentials
Why is Ca important?
(1) bone strength and density
(2) enzymes
(3) muscle contraction
(4) nerve impulses
(5) clotting
____ triggers the release of PTH.
low Ca serum levels
_____ triggers the releases of thyrocalcitonin (TCT).
high Ca serum levels
Why is Mg important?
(1) muscle contraction
(2) carb metabolism
(3) generate energy stores
(4) blood coagulation
(5) cell growth
The main goal of PTH is to what?
Increase blood Ca levels
The main goal of TCT is what?
To manage blood Ca levels by decreasing them
Fluid intake or retention is less than what is needed to meet body’s fluid needs
Dehydration
loss of total body water, such as when water shifts from plasma into the interstitial space
vascular dehydration
Older adults are at higher risk of dehydration because of what?
Age-related muscle mass loss.
Name 3 other risks for older adults and dehydration (besides muscle).
(1) decreased thirst sensation
(2) decreased mobility
(3) medications
What is the most common type of fluid loss problem?
Isotonic dehydration
Isotonic dehydration
loss of water and electrolytes
What is the main overarching risk of dehydration?
Reduced perfusion
a weight change of 1 lb corresponds to a fluid volume change of ____.
500 mL
Why is orthostatic hypotension important in dehydration?
Increased fall risk
Assess skin turgor in older adults by pinching _____ rather than back of hand
skin over sternum
What is one early indication of fluid imbalance in older adults?
Changes in cognition
What is the threshold of urine output that is cause for concern (no kidney disease)?
500 mL/day
Hemoconcentration
Increasing blood concentration
Name the 2 priority problems for dehydration
(1) fluid and electrolyte balance
(2) potential for injury d/t poor perfusion
Name the 3 nursing priority interventions for dehydration
(1) fluid replacement
(2) drug therapy
(3) patient safety
3 key signs of fluid overload are what?
(1) bounding pulse
(2) difficulty breathing
(3) neck vein distention in upright position
IV fluids with water, electrolytes, and other water-soluble substances (glucose)
Crystalloids
How do you calculate amount of fluid needed for dehydration tx?
Pt weight loss and symptoms
IV fluids that contain larger non-water-soluble molecules to increase osmotic pressure in plasma volume
Colloids
What are the two most important areas to monitor during rehydration?
Urine output
Pulse rate & quality
A well-rehydrated pt should have a daily fluid intake of what?
1500 mL
What is the most common type of fluid overload?
Hypervolemia
The two conditions related to fluid overload are what?
(1) Excessive intake
(2) inadequate excretion of fluids
Shallow respirations and increased RR are s/s of what?
Fluid overload
Name the 4 nursing priorities for fluid overload
(1) ensure pt safety
(2) restore normal fluid balance
(3) provide supportive care
(4) prevent future fluid overload
The nurse should assess the pt with fluid overload at least ____ to recognize pulmonary edema
every 2 hours
Patients with fluid overload are at risk for which 4 conditions?
(1) pulmonary edema
(2) heart failure
(3) electrolyte dilution
(4) edema
furosemide, conivaptan, and tolvaptan are drugs used to treat what?
Fluid overload
Daily weights are important because they determine what?
Treatment decisions
What is the best indicator of fluid retention and overload?
Weight gain
When should the pt report weight changes?
more than 3 lb gain in a week;
2 lb gain in 24 hours
How do you treat dehydration?
Isotonic Na+ containing solution and water
.9% normal saline is a ____ solution
isotonic
.45% normal saline is a ____ solution
hypotonic
If a person has fluid overload, name at least 3 nursing interventions
(1) stop fluids
(2) ask for order for diuretics
(3) raise HOB to high fowler’s / 60 degrees
(4) monitor K
(5) monitor I&Os
(6) daily weights
