fluid and electrolyte imbalance, GI bleeds, blood components Flashcards
who is likely to develop fluid volume defect?
older adults b/c decreased muscle mass, increased fat stores, and a reduction in the percentage of body fluids
Intracelllular compartment and how fluid gets drawn into the cells
fluid is “inside the cells”
negatively charged ions within the cells attract positiviely charged ions like Na and K which draws fluid into the cells
sodium–potassium pump
located in cell membrane
requires ATP for energy to actively move Na from the cell into the ECF and move K into the cell.
water is attracted to Na so if follows Na into the ECF which equals ICF balance
what happens hen sodium-pottassium pump fails
Na accumulates inside the cell which causes retention of water inside the cell and accumulation of K outside the cell
extracellular compartment
fluid outside the cells
divided into the intravascular fluid (plasma within blood vessels) and transcellular fluid (CSF, peritoneal fluid, synovial fluid)
osmosis
diffusion or movement of water across the cell membrane
from area of lesser concentration to an area of greater concentration of solutes
its a passive process (requires no energy)
it maintains fluid equilibrium between fluid compartments
startling forces
there are 4 forces to control movement of fluid between interstitial and intravascular compartments
they are: capillary hydrostatic pressure, capillary oncotic pressure, interstitial hydrostatic pressure, and interstitial oncotic pressure
what are the two main mechanisms regulate and maintain body fluid homeostasis
thirst via hypothalamus regulation
excretion of body water through kidneys via the endocrine system regulation
what are osmoreceptors
they are stimulated when: there is decreased blood volume, increased serum osmolality, and mouth dryness
They stimulate the pituitary to release ASH which increases water resorption into the plasma
what are arterial baroreceptors
they detect pressure changes
when they sense a decrease in pressure they send a signal to the ANS
which causes vasoconstriction of renal arteries which reduces urine output to increase circulating blood volume
They also detect increased pressure and cause vasodilation
what are the 3 endocrine regulation responses
there are three: adrenocorticotropic hormone (ACTH), antidiuretic hormone (ADH), and the renin-angiotensin-aldosterone system (RAAS).
adrenocorticotropic hormone (ACTH)
stress response- hypothalamus sends signal to pituitary gland and releases ACTH which stimulates the release of aldosterone
(aldosterone = salt regulating hormone which regulates water balance)
causing sodium resorption and potassium is excreted by kidneys. this increases circulating blood volume by increasing water resorption = increases blood pressure
antidiuretic hormone (ADH)
hypothalamus osmoreceptors detect a change of concentration of body fluid , it sends a message to pituitary to either decrease or increase ADH (which is a vasopressin)
ex. osmolality increases which causes ADH to increase the permeability of renal tubes and ducts allowing large volume of water to be resorbed. results in expands ECF, decreases serum osmolality and improves blood pressure and perfusion
renin-angiotensin-aldosterone system (RAAS).
when NA is low or K is high or blood volume/pressure is low the kidneys releases renin which then releases angiotensin 1, which is converted to angiotensin 2 in lungs .
Angiotensin 2 stimulates release of ADH and aldosterone which causes retention of sodium and water by the kidneys = rapid increase in BP = improves perfusion
what includes assessment of fluid balance (history)
injury or disease process that can alter fluid balance?
-surgery, NG tube, hyperventilation, N/V
medications?
-diuretics, laxatives, NSAIDs, glucocorticoids
dietary restrictions?
-NPO, low sodium diet, N/V, tube feeds, anorexia
intake and outputs?
-imbalance?
assessment of fluid balance: vitals
temperature- increase due to excess loss of water and Na
pulse- tachycardia due to decreased intravascular volume
resps- dyspnea due to K and/or Mg levels
BP- orthostatic BP can show dehydration, blood loss
assessment of fluid balance: inspection
sunken eyes vs round edematous face
oral tissues/tongue moist or dry
tongue furrows = FVD
jugular venous pressure- specifically he right vein
hand veins distention
hypovolemia= venous filling takes >5sec
distention should disappear within 5 sec when hand is elevated
hypervolemia = distention that doesn’t clear within 5 sec
extremities for edema
assessment of fluid balance: palpation
skin turgor (forehead, sternum, inner thigh)
*older adults will normally have reduced skin turgor bc of elasticity
cap refill - hypovolemia = prolonged (many factors like smokers, cold temp, anemia can effect results)
extravascular accumulation (second or third spacing) = high risk for hypovolemia
edema - pitting or non pitting
generalized = edema all over body (results from malnutrition)
localized = confined areas which causative condition effects capillaries/lymph tissues (ex. HF = lower extremities, sacrum)
ascites (accumulation of fluid in peritoneal cavity) can form into pleural effusion which can cause hemodynamic instabilitythird spacing of fluids
is the shift of fluid from the intravascular compartment into a “third” (transcellular) space—usually a serous cavity, such as the pericardial or pleural sac
S+S: can manifest as ascites and pericardial or pleural effusions. they are difficult to assess bc it is deep structures.usually need Xray/echo
assessment of fluid balance: body weight
peripheral edema develops when 5L or more fluid accumulates in interstitial spaces
Pitting edema develops with accumulation of 10L
Weight gain or loss of 1kg represents a fluid gain or loss of about 1L
DAILY WEIGHTS is valuable
assessment of fluid balance: auscultation
heart- may reveal 3rd or 4th heart sound with fluid overload
Tachy and hypo = fluid volume defect
pericardial friction rub can hear = accumulation of fluid in pericardial sac around heart = pericardial effusion (complication w/ kidney failure)
lungs- valuable for presence of pulmonary edema (occurs when fluid shift from vascular space into pulmonary interstitial (can indicate HF or ARDS) can hear crackles that don’t clear with cough = fluid overload
assessment of fluid balance: percussion
pain w/ percussion of flank area = UTI thats extended into kidneys
of abdomen - ascites
pt w/ Renal and/or liver failure can have ascites
assessment of fluid balance: hemodynamic monitoring (pressure and urine)
CVP/AWP/CO/CI/MAP
with fluid excess, all will show high pressure
with fluid deficit all will show low pressure
urine- low urine = FVD and high urine = FVE
urine concentration measured in two ways
1) urine specific gravity = measures ability of kidneys to concentrate urine
if increased = higher concentration = FVD
if decreased = FVE bc kidneys cannot concentrate urine
2) urine osmolality (more accurate if patients have protein or glucose in urine).
is concentration of solute in urine
increased = FVD as kidneys hold onto water (urine output decreases)
decreased = FVE kidneys excrete more water (UO increases)
assessment of fluid balance: laboratory assessment
BUN - by product of protein metabolism
low = over hydration, malnutrition, low protein
high = dehydration, kidney injury, high protein
creatinine - byproduct of muscle breakdown + filtered by kidneys
low = pregnant
high = kidney injury, shock, heart disease
BUN to creatinine ratio - ratio between the two
low = liver disease, excessive IV fluid intake, over hydrated
high = hypovolemia, shock, GI bleeding, kidney injury, muscle or tissue injury
osmolality- serum concentration
low= FVE
high = FVD
anion gap- measures difference between (-) and (+) charged ions
low = metabolic alkalosis, severe dehydration
high = metabolic acidosis, kidney injury
albumin - plasma protein, maintains vascular osmotic pressure
low = liver failure, malnutrition, kidney injury
high = dehydration, severe diarrhea/vomiting
assessment of fluid balance: urinalysis
measure pH (normal is 5) alkaline urine = vegetarian or infection glucose in urine = pregnancy or DM protein = glomerular basement membrane disease heme in urine = blood present
creatinine clearance - provide info about kidney function to measure GFR
when renal function decreases, this lab value decreases
Electrolytes
electrically charged microsolutes found in body fluids. There are two types of electrolytes: cations (positively charged ions) and anions (negatively charged ions).
major extracellular lytes are Na, Cl, Ca
major intracellular lytes are K, Mg, Po4
Sodium
responsible for water balance and is required for the normal transmission of impulses across muscle and nerve cells
plays an important role in maintaining acid–base balance by combining with chloride or bicarbonate to increase or decrease serum pH
High Na = fluid volume in intravascular compartment increases = kidneys increase urine excretion of sodium , inhibits ADH which prevents resorption of sodium by kidneys and aldosterone release is suppressed = enhancing excretion of sodium
low Na = plasma volume decreases, which triggers the RAAS causing increased sodium resorption = increasing urine output and fluid volume
sodium and water balance
sodium level changes alter water balance
water is drawn to sodium =
high sodium in ECF pulls water from intracellular spaces ( results in shrinking of intracellular compartment and expansion of extracellular compartment
this expansion can cause HF and pulmonary deem
when sodium levels are low water moves from low sodium concentration (EC) to high sodium concentration (intracellular) which causes excess volume in intracellular compartment and fluid volume defect in extracellular compartment
Chloride
works with sodium, they follow closely to sodium levels because chloride follows sodium in body
aldosterone regulates chloride levels (stimulates resorption of sodium in the kidneys)
Cl maintains osmolality of extracellular fluid space (acid-base status) which requires balance. sodium must be balance with chloride and bicarbonate.
chloride and bicarbonate compete for sodium
ex. if patient is getting too much sodium bicarb, there will be less chloride = hypocholermia
Calcium
enters body through diet and is absrobed in intestine
excess Ca is excreted through stool and urine
is required for blood coagulation, neuromuscular contraction, enzymatic activities, and bone integrity.
Ca is regulated by PTH, calcitonin and calciferol
Ca needs vitamin D to be activated by the kidneys in order to be absorbed
when Ca is low= PTH released + stimulates conversion of calcidiol to calciferol
when Ca high = PTH secretion is surpassed and calcitonin is secreted which inhibits release of calcium from bone into the blood = inhibits absorption in the intestines
