Lecture 3: Management of Common Fluid Imbalances Flashcards
what % of adult body weight is water
60
what are the 2 body fluid compartments
- extracellular
- intracellular
what is extracellular fluid (ECF)
- 1/3 of body water
1. Intravascular: plasma (5%) (liquid portion of blood) - btwn cells: interstitial (15%) and lymph (immune system fluid)
2. Transcellular fluid (CSF, GI tract, pleural spaces, synovial spaces, peritoneal spaces)
intracellular fluid (ICF)
- 2/3 of body water
- located within cells
(40% of body weight)
calculation of fluid gain/loss
1 L of H20 weighs 1 Kg
body weight change is a great indicator of fluid loss (ex: daily weights)
if a pt is on a diuretic loses 2kg in 24 hrs they have lost approx 2 L of fluid
what are electrolytes
- molecules dissociate into ions when in water
- cations: positively charged (Na+,K+,Ca2+, Mg2+)
- anions: -‘ve charge (bicarbonate, Cl-, phosphate)
measurement of electrolytes
mmol/L
mech for controlling fluid and electrolyte movement
- diffusion
- facilitated diffusion
- active transport
- osmosis
- hydrostatic pressure
- oncotic pressure
what is diffusion
movement of molecules from high to low concentration
- membrane separating the 2 areas must be permeable to diffusing substances
- no ATP
facilitated diffusion
- movement of molecules from high to low concentration
- no ATP
- uses specific carrier molecules to accelerate diffusion
- glucose transport into the cell
active transport
- process in which molecules move against concentration gradient (ex: Na-K pump)
- external energy required
osmosis
- movement of h2o btwn 2 compartments by membrane permeable to h2o but not solute
- moves from low to high solute
- no ATP
osmotic pressure
amount of pressure required to stop osmotic flow of water
- determined by concentration of solutes in solution
osmolality
concentration of molecules per weight of water
plasma (liquid portion in blood) osmolality is 280-300 mmol/kg
oncotic pressure
(colloidal osmotic pressure)
- osmotic pressure exerted by colloids in solution
major collioid in vascular sys contributing to total osmotic pressure is albumin
albumin
- protein made by liver
- keeps fluid in vascular space
- albumin is low, fluid leaks out of vascular space
fluids with the same osmolality as the cell interior are ->
ISOTONIC, normally the ECF and ICF are isotonic to one another
fluids in which solutes are less concentrated than they are in cells are
HYPOTONIC (goes in)
fluids in which the solutes are more concentrated than they are in the cells are
HYPERTONIC (goes out)
hydrostatic pressure
- force within fluid compartment
- major force that pushes water out of vascular sys at capillary level
Fluid shifts
- plasma -> interstitial fluid shift = EDEMA
- increased venous hydrostatic pressure
- decrease in plasma oncotic pressure
- elevation of interstitial oncotic pressure - interstitial fluid -> plasma
- fluid drawn into plasma space with increase in plasma osmotic or oncotic pressure
- increasing the tissue hydrostatic pressure
what can help decrease peripheral edema
compression socks
fluid spacing (1st, 2nd, 3rd)
1st: normal distribution of fluid in ICF and ECF
2nd: abnormal accumulation of interstitial fluid (edema)
3rd: fluid accumulation in part of body where it is not easily exchanged w ECF
what regulates water balance
hypothalamic
pituitary
adrenal cortex
renal
cardiac
gastrointestinal
insensible water loss
serum electrolytes: Na
responsible for maintaining osmotic pressure
norm: 135-145 mmol/L
serum electrolytes: K
component in cardiac function
norm: 3.5-5 mmol/L
serum electrolytes: Cl
in combo w Na, Cl maintains fluid levels by reg osmotic pressure
norm: 95-105 mmol/L
serum electrolytes: bicarbonate (HCO3)
major buffer in body, helping to maintain proper blood pH
norm: 21-28 mmol/L
serum electrolytes: urea nitrogen (BUN)
urea is the waste product resulting from protein metabolism
norm: 2.5-6.4 mmol/L (adult)
serum electrolytes: creatinine (CR)
waste product when muscle tissue uses energy sources
norm: 71-106 umol/L
normal intake in adult
fluids - 1200 ml
solid food - 1000 ml
water from oxidation 300 ml
total intake - 2500 ml
normal output in adult
- insensible loss (skin and lungs) - 900 ml
- in feces - 100 ml
- urine - 1500 ml
total output: 2500 ml
ECF volume imbalances
- commonly occur
- accompanied by 1 or more electrolyte imbalanced
either have:
1. ECF volume deficit = hypovolemia
2. ECF volume excess = hypervolemia
what is hypovolemia
ECF volume deficit
- decrease in blood volume
- body can compensate, causing kidneys to retain xtra water and Na
causes of hypovolemia
- decreased intake
- increased loss
populations at risk for hypovolemia
- kids: immature kidneys, higher metabolic rate, immature endocrine sys, greater BSA
- elderly and disabled: chronic med conditions, decreased thirst response, decreased mobility, med effects
how to look for hypovolemia
- neuro changes: weakness, restlessness, agitation, twitching
- cardio: increased HR, orthostatic hypotension, weak, thready pulse that is easily obliterated and flattened neck veins
- resp change: increased RR
- renal: decreased urine output
weight loss
decreased skin turgor
3 types of IV solutions
- Isotonic solutions (have same effective osmolality as body fluids (close to 285 milliosmoles [mOsm]). An example of an isotonic fluid is 0.9% sodium chloride & lactated ringers
- A hypotonic solution (has a lower osmolality than body fluids; an example of a hypotonic fluid is 0.45% sodium chloride
- A hypertonic solution has an effective osmolality greater than that of body fluids; an example of a hypertonic fluid is 3% sodium chloride
normal saline
0.9% NaCl
- Expands IV volume
- Preferred fluid for immediate response
- does not change ICF volume
- run w blood products; versatile
- compatible w most meds
lactated ringers
- the solution is isotonic w blood and intended for IV admin
D5W
- 5% dextrose
- isotonic
- 170 cal/L
- Free water
- Moves into ICF
- can cause urinary Na loss
- used to replace water losses
- does not provide electrolytes
cbc
complete blood count
3 categories:
1. leukocytes
2. erythrocytes (hemoglobin [protein compound that bind w o2], and hematocrit [% of RBC])
3. platelets
hemoglobin amount norm
female: 7.4-9.9 mmol/L
male: 8.7-11.2 mmol/L
low hemoglobin
not enough o2, could be an iron deficiency, too much fluid in blood because it has diluted the red blood cells, also that they have lost a lot of blood, anemia, cancer
high hemoglobin
to low fluid, if you live at a high altitude, bone marrow disfunction, blood doping,
hematocrit levels
female: 0.35-0.47 volume fraction
male: 0.42-0.52 volume fraction
low hematocrit
fluid volume excess
high hematocrit
fluid volume deficit (causes dehydration)
ECF volume excess (hypervolemia)
- abnormal increase in blood volume
- kidneys to release additional water and sodium
causes: increased retention (CHF, chronic liver disease, renal failure), increased intake (rare w adequate renal function, excessive IV administration of fluids
sympt:
apathy, confusion, pulse not easily obliterated, increased bp, SOB
(neuro, cardio, resp)
edematous skin
1+ (2mm indentation) to 4+ (pitting, 8mm indentation)
