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?
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