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1. A form of filtration to separate crystalloid from colloid substances (or smaller molecules from larger ones) in a solution by interposing a semipermeable membrane between the solution and dialyzing fluid; the crystalloid (smaller) substances pass through the membrane into the dialyzing fluid on the other side, the colloids do not. 2. The separation of substances across a semipermeable membrane on the basis of particle size and/or concentration gradients. 3. A method of artificial kidney function. [G. a separation, fr. dialyo, to separate]
- continuous ambulatory peritoneal d. (CAPD) method of peritoneal d. performed in ambulatory patients with influx and efflux of dialysate during normal activities.
- equilibrium d. in immunology, a method for determination of association constants for hapten-antibody reactions in a system in which the hapten (dialyzable) and antibody (nondialyzable) solutions are separated by semipermeable membranes. Since at equilibrium the quantity of free hapten will be the same in the two compartments, quantitative determinations can be made of hapten-bound antibody, free antibody, and free hapten.
- peritoneal d. removal from the body of soluble substances and water by transfer across the peritoneum, utilizing a d. solution which is intermittently introduced into and removed from the peritoneal cavity; transfer of diffusable solutes and water between the blood and the peritoneal cavity depends on the concentration gradient between the two fluid compartments.
- d. retinae congenital or traumatic separation of the peripheral sensory retina from the retinal pigment epithelium at the ora serrata, often causing a retinal detachment. SYN: retinodialysis.
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1) the separation of substances in solution by means of their unequal diffusion through semipermeable membranes esp such a separation of colloids from soluble substances
2) either of two medical procedures to remove wastes or toxins from the blood and adjust fluid and electrolyte imbalances by utilizing rates at which substances diffuse through a semipermeable membrane:
a) the process of removing blood from an artery (as of a kidney patient), purifying it by dialysis, adding vital substances, and returning it to a vein called also hemodialysis
b) a procedure performed in the peritoneal cavity in which the peritoneum acts as the semipermeable membrane called also peritoneal dialysis
di·a·lyt·ic .dī-ə-'lit-ik adj
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n.
a method of separating particles of different dimensions in a liquid mixture, using a thin semipermeable membrane whose pores are too small to allow the passage of large particles, such as proteins, but large enough to permit the passage of dissolved crystalline material. A solution of the mixture is separated from distilled water by the membrane; the solutes pass through the membrane into the water while the proteins, etc., are retained. The principle of dialysis is used in the artificial kidney (see haemodialysis). The peritoneum is used as an autogenous semipermeable membrane in the technique of peritoneal dialysis, which is employed when haemodialysis is not appropriate.
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di·al·y·sis (di-alґə-sis) [Gr. “dissolutionâ€] 1. the process of separating macromolecules from ions and low-molecular-weight compounds in solution by the difference in their rates of diffusion through a semipermeable membrane, through which crystalloids can pass readily but colloids pass very slowly or not at all. Two distinct physical processes are involved, diffusion and ultrafiltration (qq.v.). 2. hemodialysis. dialytic adjMedical dictionary. 2011.