IV Fluids Flashcards
1
Q
What are diff fluid and lyte disorders in a surgical pt?
A
- disorders of volume: depletion excess - disorders of lyte concentrations: sodium potassium chloride calcium Mg phosphate
2
Q
What is the sequelae of inapprop fluid and lyte management?
A
- increased length of stay
- increased cost
- wound infection
- delayed wound healing
- anastomotic failure
- tachyarrhythmias
- cerebral edema, seizures, death
- pulm edema, CHF, renal failure
3
Q
What are you trying to accomplish w/ IV fluids?
A
- maintenance therapy:
if pt isn’t expected to eat or drink for a period of time - replacement therapy:
correct abnormalities in volume and/or lytes - volume resuscitation: hypotension, hemorrhage
4
Q
Total body water in diff pop groups?
A
- directly proportional to muscle mass: muscle mass is about 70% water
- inversely proportional to fat: fat is about 10% water
- neonates: 75-80% body wt is water
- young healthy fit female:
on avg 55% of body wt is water - young healthy fit male: 60% of body wt is water
- total body water decreases in:
morbidly obese, elderly, or low muscle mass due to disease or injury
may be as little as 35%
5
Q
Total body water consists of what 2 main compartments?
A
- intracellular fluid:
- fluid w/in cells
2/3 TBW, in 70 kg man - 28 L - extracellular fluid: 1/3 TBW, 14 L (70 kg man)
6
Q
Components of ECF?
A
- the fluid outside of cells
- plasma (vascular space):
Na+ main cation, other cations: K+, Ca++, Mg++
anions: Cl-, HCO3-, proteins, sulfates, organic acids - interstitial space:
same as plasma but lower concentration of protein
7
Q
Components of ICF?
A
- K+ and Mg++ main cations
- main anions: phosphates, sulfates and proteins
8
Q
Diffusion of proteins and ions?
A
- free diffusion is limited
- Na+ stays mainly outside of cell
- K+ stays mainly inside cell
- water may diffuse freely among all compartments
9
Q
Movement of water?
A
- passive
- exchange of water b/t intracellular and interstitial compartments is determined by osmotic gradients
- ex: if ECF is hypo-osmolar: water will go into cells where the osmolarity is higher until equilibrium is reached
10
Q
Normal body osmolarity? When will hyperosmolarity occur?
A
- normal = 285 osmol/L
- hyperosmolarity will occur in both ECF and ICF if extracellular osmolartiy is increased: fluid will move from ICF to ECF and leave the ICF more concentrated from loss of water so becomes hyperosmolar
- fluid constantly moves among intracellular, interstitial and vascular spaces to maintain balance
11
Q
What are the crystalloids?
A
- dextrose in water: D5W, D10W, D50W
- saline: isotonic (.9%), hypotonic (0.45% or 0.225%), hypertonic (3% or 5%)
- combo:
D5 1/2 NS, D5 NS, D10 NS - LR (K, HCO3, Mg, Ca)
- these solns contain small molecules and are able to pass through semipermeable membranes
- soln transfers easily across cell membrane of blood vessels
12
Q
What are the colloids?
A
- albumin: 5% in NS, 25% (salt poor)
- dextran
- hetastarch
- blood
- FFP
- solns that contain high MW proteins (like albumin) or starch
- don’t cross capillary semipermeable membrane
- remain in intravascular space (pulling fluid out of intracellular and interstitial space) for several days
13
Q
Crystalloids vs Colloids use?
A
- crystalloids are generally adequate for most situations needing fluid management
- colloids may be indicated when more rapid hemodynamic equilibration is reqd
- composition of soln and rate of admin are impt when addressing a specific situation
14
Q
Diff b/t iso/hypo/hyper-tonic?
A
- isotonic: given to expand ECF volume
- hypotonic: given to reverse dehydration
- hypertonic: given to increase ECF vol and decrease cellular swelling
15
Q
How do isotonic fluids work?
A
- have same osmolality as plasma so fluids remain primarily in ECF
- Isotonic IV fluids are used to replace ECF losses and to expand vascular volume quickly
16
Q
Diff isotonic fluids used?
A
- normal saline: provides Na and Cl in water w/ same osmolality as serum, no calories or free water
- Ringers soln: contains Na, K, Ca in similar concentrations to plasma but no dextrose, Mg, or bicarb, no calories or free water
- LR: contain Na, Cl, K, Ca, and lactate in concentrations similar to normal plasma, no dextrose, Mg or free water
17
Q
How do hypotonic solns work? When are these CI?
A
- lower osmolality than normal plasma
- increases cell water by pulling water out of vessels into cells: results in decreased vascular vol and increased cell water
- used to prevent and tx cellular dehydration by providing free water to cells
- CI in acute brain injuries b/c cerebral cells are very sensitive to free water, absorbing it rapidly and leading to cerebral cellular edema
18
Q
Diff hypotonic fluids used?
A
- D5W: although isotonic in IV bag, has hypotonic effect in body as dextrose is quickly metabolized: leaving free water that shifts osmosis from vessels into cells, dextrose content doesn’t meet daily nutritional caloric requirements but it does prevent starvation
- 1/2 NS or 1/4 NS: these fluids provide free water to cells as well as small amts of Na and Cl often used as maintenance fluids
19
Q
When are hypertonic fluids used?
A
- these have higher osmolality than normal plasma: causes water to be pulled from cells into vessels, resulting in increased vascular volume and decreased cell water
- used to tx very specific problems: admin in carefully controlled, limited doses to avoid vascular volume overload and cell dehydration - pulls excess fluid from cells and to promote osmotic diuresis
ex:
saline solns that are more than 0.9% - these are used infrequently
20
Q
diff b/t isotonic, hypotonic and hypertonic fluids?
A
- isotonic: stays inside bloodstream or intravascular compartment (0.9% NS, LR)
- hypotonic: will shift and flow into a more concentrated soln (drays fluid from vessels and into cells - D5W, 0.45% NS)
- hypertonic: will pull a less concentrated soln into itself (tx severe low Na levels - 3% or 5% NS)
