DIALYZER Yousaf khanRenal dialysis lecturerIPMS-KMU

DIALYZER Dialyzer shell

(polyurethane) is a box or tube with four port (2 blood and 2 dialysis)

Dialyzer – blood and dialysis solution

Movement of molecule across semipermeable membrane

DIALYZER

An ideal dialyzer should have High clearance of small and medium MW toxins Adequate UF Negligible losses of protiens and amino acids Non toxic composition Minimal activation of cell or thrombotic pathways Minimal blood volume Reliability Reusability Low cost

DIALYZER TECHNICAL SPECIFICATION Priming volume very from 40-150 ml. Surface area vary from 0.5-2.2m2

KUF from 2.5 to 85ml/h/mmHg KoA urea varies from 200 to 1200 (<300 represents a

low efficiency dialyzer and >600 a high efficiency dialyzer)

Specification sheets also provide clearance for urea and vitamin B12.

Dialyzer are sterilzed by gamma irradiation, ethylene oxide or by steam

Must be pre rinsed with >2L rinsing solution prior to connecting to patient to prevent release of fragments from the dialysis circuit

DIALYZER MEMBRANECellulose: Obtained form processed cotton (regenerated

cellulose, cuprammonium cellulose, cuprammonium rayon and saponified cellulose)

Substituted cellulose: Cellulose polymer has a large number of free hydroxyl

group at its surface Free hydroxyl group are responsible for blood cell

activation causing bio-incompatibiltiy of the dialyzer (cellulose acetate, cellulose diacetate, triacetate)

DIALYZER MEMBRANECellulosynthetic: A synthetic material ( a tertiary amino compound) is

added to liquefied cellulose during formation of the membrane as result the surface of the membrane is altered and biocompatibility is increased (cellosyn or hemphan)

Synthetics: Not cellulose based but are synthetic plastics and

materials used include polyacrylonitrile (PAN) polysulfone, polycarbonate, polyamide and polymethyl-methacrylate (PMMA)

DIALYZER TYPESCoil dialyzer: Flattened cellulose tubing wrapped as a coil and

through which patients blood flow during dialysis. The blood channels was long to obtain the needed

surface area, and resistance was high UF was unpredictable and blood leak were frequent.

PARALLEL PLATE DIALYZER Sheets of membrane are placed between supporting plates. The plates have ridges and grooves to support the membrane and

allow flow of dialysate along it Resistance to blood flow is low. The surface area vary from 0.25 to 1.5

msq.Advantage: Blood volume is about 50-100 ml at 100 mmHg increase with high TMP Heparin requirement usually low, minimal clotting in the blood

compartment Ultrafiltration is reasonably predictable and controllable

Disadvantage: Formation of local thrombi around inlet and outlet ports and corners May lead to bacterial growth and endotoxin formation therefore plates

are not often reused

HOLLOW FIBER DIALYZER Numerous hollow fiber Hollow fiber are tiny its diameter 150-250um Number of fiber20000 or more, depending upon length, kind of

membrane and surface area of dialyzer

Advantage : Low blood volume 60-90ml Resistance to blood flow is low Ultrafiltration can be precisely controlled Well adapted to reuse

Disadvantage: Deaeration of fiber predialysis is necessary to prevent air lock of the

fibers More heparin is required for most of the patients Adverse patient reaction

DIALYZER TYPE

REACTION TO MEMBRANESType A reaction Within minutes of

starting dialysis with Dyspnoea, wheeze A feeling of warmth,

urticaria Cough, hypotension Collapse or cardiac

arrest

Type B reaction More common but much

milder often occur 20-40 min after starting dialysis

Usually cause back and chest pain

Thank you