Types of IV fluid, fluid balance Flashcards
3 main types of IVF and how do they differ?
• Isotonic fluids
• Hypotonic fluids
• Hypertonic Fluids
Differ in their influence on fluid shifts between vasculature, cells, and interstitial space. We CANNOT measure osmolality of cells/tissues because it would require taking out cells and looking at them so instead we draw blood then make educated inference
isotonic fluids and tonicity/shifts/risks?
volume expander. Expands vasculature with volume: doesn’t cause ANY fluid shifts.
EVENTUALLY if you force enough in there, then there are other forces moving stuff in/out. but just tonicity itself doesn’t do anything to anything other than just vessels.
• Osmolarity similar to serum.
• Fluids remain IVS, expand volume.
• Risk of fluid overloading exists: caution w/Left ventricular dysfunction, history of CHF, HTN
isotonic fluid indications
hypotensive, hypovolemic pts
isotonic fluid contraindications
•Avoid volume hyper-expansion in pt with intracranial pathology or space occupying lesions.
hypotonic indication, fluid shift, example of hypotonic fluid?
give for cellular dehydration.
lower osmolarity than serum: dilutes serum decreasing osmolarity.
•Water moves from the IVS to ISC –> dilutes interstitial fluid –> osmolarity decreases –> water drawn into cells
*Sometimes pharmacy will put something like antibiotic in 1/2 NS (hypotonic) because it would draw antibiotic into the cell. (it’s a little faster)
hypotonic fluid cautions
Sudden fluid shifts from IVS
- Cardiovascular collapse
- increased icp in certain patients
hypotonic fluid contraindication
hypovolemia, hypotensive in the vasculature because hypotonic fluid will draw it away from bloodstream even more
hypertonic fluid indications, shifts
For stabilizing BP, increasing urine output, correcting hypotonic hyponatremia, decreasing edema.
Higher osmolarity than serum, fluid drawn into bloodstream (vasculature).
• Fluid ( & electrolytes) from ICS/ ISC into
IVC.
hypertonic fluid shift cautions
•These can be dangerous in the setting of dehydration of cells.
Can be helpful for edema: draws fluid out of the interstitial space also. But also draws fluid from cells, may cause dehydration.
cellular vs intravascular dehydration
If pt only has cellular dehydration, not vasculature, BP will be normal. So BP is the “window” for seeing how much fluid is in vasculature.
what is more important? cellular or vasculature dehydration? what if pt has both?
What we’re concerned about with dehydration in the vasculature, we are worried about NOT PERFUSING ORGANS causing like acute renal failure. So prioritize dehydrated vasculature over dehydrated cells.
If you have both problems, don’t use hypertonic/hypo cause even if it helps one problem it makes cells worse. Only give isotonic soln if you have both dehydration problems. It’ll bring BP back up, perfuse organs (addressing vasculature first). Eventually, there’s so much fluid in vasculature (not a tonicity change) that itll get pushed out into the interstitial space then into the cells and just by force of excess volume and so it’ll also solve that problem with the cells
dehydrated cells s/s
might affect functioning of the tissue little bit
Dry mucous membrane, orthostatic hypotension, poor skin turgor, steady BP
dehydration of vasculature
hypotension, cardiac problems, dizziness, flattened neck veins
2 main groups of fluids
- Crystalloids: Normal Saline, Lactated Ringers (hypo, hyper, iso, come in big bags). Clear, water/electrolyte solutions, small molecules.
- Colloids: Blood, Blood Products, plasma, plasma fractions, synthetic plasma expanders (synthetic albumin). tend to be hypertonic
crystalloids advantages
-Inexpensive
-Easy to store with long shelf life
-Readily available with a very low incidence of ac
reactions
-Variety of formulations that are available that al
for use as replacement fluids or maintenance flu
crystalloids disadvantages
takes approx 2-3x more volume of a crystalloid to cause the same IVS expansion as a single volume of colloid.
how is albumin a plasma expander?
doesn’t leave vasculature because its too big, takes up space and therefore draws fluid into its area
pt gets shot, bleeding a lot, low volume. What’s the tx?
pump them up with clear crystalloids (isotonic) so it can stay in the vasculature. That will bring volume back up. meanwhile, we are cross matching and blood typing cause we wanna give him blood.
We wanna give him blood because blood has more than just small molecules like isotonic soln. Has proteins
why is isotonic crystalloid not a good long term soln for dehydrated pt?
eventually theres so much volume, itll push out.
colloids
volume expanders.
have a VERY STRONG OSMOTIC FORCE
• Colloids are large molecular weight solutions
-Do NOT readily cross semi-permeable membranes
• High osmolarities
-Important in capillary fluid dynamics
-Causes osmotic force across the wall of the capillaries
Initially stay almost entirely in the IVS for a prolonged period of time compared to crystalloids.
colloid indication
• Reducing edema, reduce third spacing, bring up volume
Draw fluid from interstitial and intracellular compartments into the vascular compartments.
crystalloids - dextrose solns
Anything wit a D added to it is gonna be hypertonic. (sugar makes you hyper). ONE EXCEPTION: D5W (D 5 weird) - instead of becoming hyper, it is isotonic while sitting on the shelf. But once you start infusing, it starts to act hypotonic.
Ex: 5% Dextrose, dextrose saline
5% dextrose
5% Dextrose (often written D5W) — Sugar and water
- To maintain water balance when NPO
- Provides some calories
- Electrolyte free
- Distribution: < 10% Intravascular; >66% intracellular
- Rapidly redistributed into ICS
- Less than 10% stays in IVS
Hardly ever see someone on D5W, more likely D5NS. With dextrose, always check if DM.
dextrose saline
- Dextrose saline — ‘a bit of salt and sugar’ D5NS
- Similar indications to 5% dextrose
- Primarily used to replace water losses post operatively
- Neither really saline or dextrose
- Advantage: doesnt commonly cause water/salt overload
Determining appropriate IVF
- Assess volume status
- What is the volume status of my patient?
- Do we want to shift fluid to another compartment?
- Can my patient take PO safely? PO fluids preferred. Taking PO same time as iv: get off IV faster.
- Is the patient NPO for a reason?
- Is the patient diabetic?
- What fluids was the patient on previously? Effects of fluids that were stopped recently will still be in their body (if it’s already been a day since off it don’t worry as much)
do we need to know the chart at the end of types of iv fluids ppt?
?
what fluid has closest makeup to blood itself?
LR is an isotonic soln that has closest makeup to blood itself.
body fluid compartments
- Intracellular Fluids (ICF) - 3/4 total body fluid
- Extracellular Fluids (ECF)
- 1/4 of ECF is plasma in intravascular space (IVS)
- 3/4 of ECF is interstitial in lymph and between cells
- supplies food, o2, h20, vitamins, electrolytes, and removes body wastes
fluid balance
• 2-2.5 liters per day Continually lost -Respiration -Urine -Feces -Perspiration Insensible water loss
fluid regulation
body is always trying to return to homeostasis.
ex: if person is hypervolemic, inhibit ADH and aldosterone, thirst is inhibited too.
effect of aging on fluid regulation
Very common effect of aging: person doesn’t have same thirst response as before. They are not thirsty even if dehydrated. Tell them to drink even if don’t feel thirsty.
osmolality
Osmolality (tonicity but in the body)
- Number of molecules of solute per kilogram of water
- Isotonic: Blood
- Hypertonic: lots of particles, hyperosmolar
- Hypotonic: losing particles, hypoosmolar
regulation of body fluid mechanisms
Osmosis
Diffusion: Simple, facilitated, Active transport
Filtration: hydrostatic pressure, osmotic pressure
osmosis vs diffusion
movement of water vs movement of particles from areas of less to more solute concentrations
filtration influenced by
- Hydrostatic Pressure
- Capillary Fluid Movement (Capillary bed is where fluid moves in/out of vacsulature)
- Oncotic Pressure
- Fluid Shifts (Not because of tonicity in filtration, but because of pressures)
hydrostatic pressures
Has everything to do with cardiac function. Pushing pressure.
- The major force in the movement of water out of the capillaries into the interstitial fluid
- Comes from force of heart pumping. arterial end pressures much higher: that’s why it pushes out.
hydrostatic pressure and the CHF pt
So patient with CHF with heart that doesn’t pump as well as it should, hydrostatic pressure (arterial pressure) may be low since heart is not pumping with enough pressure. That’s why we don’t give em a lot of fluid.
hydrostatic presure vs isc
One factor that determines whether fluid leaves the blood vessels and enters the tissue spaces (interstitial fluid) is the difference between the hydrostatic pressure of
capillary blood and that of the interstitial fluid.
increased venous hydrostatic pressure?
Stuff’s not being properly pushed out ie in CHF, or for some other reason holding onto stuff in vasculature, will bring VP up, so things don’t get pushed back in.
Increase venous pressure can also be from kidney/liver failure.
Movement of fluid blocked by higher vp than normal; edema.
oncotic pressure, what is it affected by
Pulling pressure. Drawing from interstitial spaces, so can be done on purpose for pts with edema. Eventually draws from the cells too tho since interstitial spaces draw from the cells
•AKA colloidal osmotic pressure caused by colloids in the serum
•Colloids are particles that are too large to pass through the capillaries
• Edema
-Plasma oncotic pressure too low, fluid is not drawn back to capillaries from interstitial space
-protein malnutrition
liver failure pt and oncotic pressure?
–liver failure patients will have fewer particles in vessels. –> edema. Their BP would actually be low and also their perfusion low because all the fluid is in the interstitial space, not in the vasculature, causing edema, all because they have decreased oncotic pulling pressure d/t decreased colloids. So don’t always confuse edema for fluid vasculature overload. Check BP.
Decrease the edema and bring up the BP at the same time by giving albumin: volume expander plus is doing it by drawing fluid from ICS, decreasing edema and bringing up BP.
what leads to capillary fluid movement?
hydrostatic/oncotic pressures. They are two SEPARATE forces that just happen to be working at the same time. They are not influencing each other.
• The amount and direction of fluid movement is based
on the hydrostatic pressure and the oncotic pressure
-Fluids normally leave to bathe the cells but return to the vessels
edema
•Fluid moves from the plasma to the interstitial spaces
- when the hydrostatic pressure in the venous vascular system rises,
- and/or the colloidal osmotic pressure plasma decreases
•Examples
- Right-sided heart failure (increased hydrostatic pressure)
- Liver failure (decreased oncotic pressure)
extreme edema
3rd spacing.
Fluid going into spaces that shouldn’t have fluid at all.
Ascites (liver failure), pleural effusion, burn pts: third spacing all over
homeostatic mechanisms
Osmoreceptors in hypothalamus • Measure osmolality Dehydration -ADH and Aldosterone - Thirst mechanism Overhydration • ADH, Aldosterone inhibited -if not corrected, can lead to third spacing. thirst mechanism diminished.
dehydration etiology
fluid volume deficit. Etiology • Lack of fluid intake • Excess fluid loss •Regulator alteration -Thirst -hormones -lymphatic system -kidneys
average daily fluid intake?
1500 to 2500 ml
know causes, body compensations, manifestations including labs, management, and pt teaching
5 things yikes
EXCESS fluid loss causes
Potential causes of excess fluid loss:
• Unmonitored use of diuretics
• Severe vomiting and persistent diarrhea
• Fever and diaphoresis
• Gastrointestinal suction and fistula drainage
• Blood loss and burns
•Third spacing of fluids (a lot of fluid in the body, but causing vascular dehydration. Not fluid in the right place)
how does the body compensate for fluid loss?
• Interstitial fluid moves to restore volume
•ADH & aldosterone increase, causing
reabsorption of sodium, water
• Baroreceptors are stimulated ->
vasoconstriction & increased HR
• Osmoreceptors signal thirst mechanism
•when compensation FAILS, individual experiences fluid volume deficit
fluid volume deficit tx
first order: keep fluid in the vasculature, then deal with dehydration of cells
effects of fluid volume deficit on osmolarity, cells, fluid
- Hypertonic dehyration: Typically water loss is greater than electrolyte loss (hypertonic loss). Meaning, the blood that’s still in the vasculature, is hypertonic. THAT means fluid from the cells and interstitial spaces will be drawn out, resulting in cellular dehydration. BECAUSE number one space to pay attention to is vasculature because of perfusion.
- Increases the osmolarity of the remaining plasma, making it hypertonic (aka hyperosmolar)
- Increased osmolarity causes water to move from the ICF into the plasma
- Results in cellular dehydration and shrinkage
- Plasma volume increases to normal or greater than normal levels
clinical manifestations of fluid volume deficit
- loss of body weight
- changes in intake/output
- changes in VS: decreased BP (initially, and particularly orthostatic hypotension), decreased CVP, increased HR to compensate, maybe a rise in temperature because metabolism is going a little faster
- dry mucous membranes, decreased skin turgor, headache, dizziness, concentrated urine, decreased urine output, tachypnea
- labs basically all go up
diagnostic findings in fluid volume deficit
Indicators of hemoconcentration •Osmolality above 295 mOsm/kg •Plasma sodium above 145mEq/L •Blood urea nitrogen above 25 mg/dL •Plasma glucose above 120 mg/d •Hematocrit above 55% •Urine specific gravity above 1.030
Management for fluid volume deficit
• Fluid restoration
- Oral or IV rehydration (Oral if you can. Cause gut can take what it wants.)
• Thorough Assessment
• Monitor for complications
• Decreased cardiac output
• Dysrhythmias
• Electrolyte imbalances
• impaired mucous membranes (dryness, cracks)
• correct the underlying problempt education: why tell parents they shouldnt give their vomiting/dehydrated child gatorade?
When doing pt teaching, teach parents not to give a vomiting/dehydrated child gatorade because it has a lot of sugar, and if they have too much sugar (like dextrose) it’ll just make pt even more dehydrated cause increasing that hyperosmolality. Gatorade is hypertonic.
If child RLY wants gatorade, do 1/2 gatorade 1/2 water
ESP bad if pt has GI problem: sugar is irritating to gI –> more diarrhea
pt education to prevent fluid deficit
• Teach:
•Appropriate fluid replacement
•Exercise with adequate fluid replacement
• Cool water before exercise
•150 to 200 ml every 15 minutes
exercise
•Do not decrease fluid intake for incontinence
•drink fluids in absence of thirst
fluid volume excess
fluid overload.
Hypervolemia
• Excess fluids in the vascular system
• Third-spacing
• Excess fluids in the interstitial spaces (spaces that don’t normally have water)
fluid volume excess etiology
- Simple overloading of fluids
- Failure to excrete fluids
* Renal failure
* Edema
* Heart failure
* corticosteroids
hypervolemia
When you have too much fluid in the vasculature, it tends to be isotonic.
-Isotonic overhydration
•Caused by problems that arise from excessive fluid in the vessels
•Osmolarity remains normal
•Only the vasculature expands and does not shift between the spaces
-eventualllyyy hydrostatic pressure increases to the point where it will push fluid into the interstitial spaces *IF pt has a healthy heart because hydrostatic pressure is all about how well the heart is pumping but hypervolemia = too much fluid in BLOODSTREAM
third spacing: what is it, causes
- Fluid accumulation in areas that normally have no fluid or a minimal amount of fluids (ascites or edema with burns)
- Either from decreased oncotic pressure
- Or from hypotonic overhydration (–> edema)
* excess fluid is hypotonic to normal body fluids
* the osmolarity of the blood decreases and hydrostatic pressure increases
* fluid moves into the intracellular space because of the decreased plasma hydrostatic pressure
patho: hydro/oncotic pressures during fluid volume excess
Hydrostatic pressure increases, pushing fluids into the interstitial spaces
Peripheral vascular resistance increases
Pulmonary edema and heart failure develop
clinical manifestations of fluid volume excess
Respiratory and cardiovascular: -Cough, dyspnea, crackles, pallor, etc. -Bounding pulse, elevated BP, CVP, JVD Other: -peripheral edema -weight gain -confusion, seizure, coma from crossing BBB during things being pushed out from being hypotonic as a LATER effect
lab indicators of fluid volume excess
Indicators of hemodilution •Osmolality less than 275 mOsm/kg •Sodium less than 135 mEq/L •Hematocrit less than 45% •Specific gravity less than 1.010 •BUN less than 8 mg/dL
management for fluid volume excess
• Restrict sodium
• Restrict fluids
.• Daily weights
• Promote urine output
• Diuretics and digitalis (if cardiac in nature to increase heart function and ability for hydrostatic pressure to push things out)
•Improve myocardial function
•Angiotensin-converting enzyme (ACE) inhibitors and beta-blockers
• Correct the underlying problem
