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29 Cards in this Set
- Front
- Back
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What is the solution used during dialysis?
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Dialysate
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What is the solvent used in dialysis?
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Water
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What are the solutes used in dialysis?
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Electrolytes (K, Ca, Na, Mg, Cl) and glucose
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What is the difference in the concentrations on either side of a semi-permeable membrane?
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Gradient
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What diffuses the slowest in dialysis?
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RBC, WBC, albumin, platelets, viruses, bacteria
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How does temperature affect diffusion?
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The warmer the fluids are, the faster diffusion occurs.
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How does the surface area affect diffusion?
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A larger surface area allows more diffusion.
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How does the way that fluids flow affect diffusion?
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A countercurrent flow speeds up diffusion because you keep a high concentration gradient b/w the blood and dialysate.
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What is the term for solvent moving across a membrane?
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Osmosis
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What is the term for solutes moving across a membrane?
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Diffusion
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When we dialysize pts, what do we take out and what do we put in?
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Typically...
Na, K, & Urea come out and HCO3 (bicarbonate) goes in. (Kidneys produce HCO3, so pts are low on this putting them in an acidotic state.) |
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What is hydraulic pressure?
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The pressure created by forcing water through a narrow pipe.
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What is filtration?
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Movement of fluid through a filter as the result of hydraulic pressure.
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What kind of pressure do we put on dialysate side?
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Negative so we pull fluid off
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What happens if you hold the flow rate constant and cut the diameter of the tube in half?
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Flow velocity doubles
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What is flow rate?
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Ml/min
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What is flow velocity?
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The speed at which the fluid moves through a given length of tubing
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What fluid compartments do we have as a human?
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Intracellular
Interstitial Intravascular |
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What fluid compartment does dialysis remove fluid from?
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Intravascular
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What is the term for the tubing and dialyzer?
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Extracorporeal circuit
(meaning "outside of the body") |
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Where is the highest pressure in the dialyzer located?
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At the arterial header (where blood enters the dialyzer fibers).
This is called the post-pump arterial pressure. |
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Where is the lowest positive pressure in the blood path?
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After the blood leaves the dialyzer (venous pressure)
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What is the average of the pressure entering and leaving the dialyzer fibers called?
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Positive hydraulic pressure.
It aids UF of H2O out of the blood. |
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What is the difference in pressure across the dialyzer membrane called?
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transmembrane pressure
Machine can control this. |
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Why do dialysis tx require more than one pass through the dialyzer?
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So that solutes have a chance to diffuse out of the intracellular space in to the intravascular space
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How do you figure out how much fluid to remove?
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Predialysis weight - Estimated dry weight (EDW) + Fluids pt will receive in tx
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How is Na used in dialysis?
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We add Na in the beginning of tx to keep the BP from crashing, then we lower Na towards the end of tx to pull Na out of the blood.
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What is the term for fluid movement ouside of the body? Inside the body?
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Ultra filtration (outside)
Osmotic forces (inside) |
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What is the sieving coefficient?
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The size and number of holes (pores) in the membrane.
1.0 mean 100% of given solute can pass through 0.4 means 40% of given solute can pass through |
