It Is The Diffusion Of Solutes And Osmosis Of Water

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It is the diffusion of solutes and osmosis of water through a passive, porous membrane from the plasma to the dialysis solution and vice-versa in response to a concentration of pressure gradient. a process that substitutes for renal function by removing excess fluid and/or accumulated endogenous or exogenous toxins. Dialysis is most often used for patients with ARF and chronic (end-stage) renal disease. The two most common types are hemodialysis and peritoneal dialysis.

Help restore normal fluid and electrolyte balance, control acid-base balance and remove waste and toxic materials from the blood.  To sustain life successfully where substitution for or augmentation of normal renal function is needed.  To remove excessive amounts of drugs and toxins (poisoning) in the blood.  To maintain kidney function when renal shutdown occurs. 

Principles involved in Dialysis: 

DIFFUSION -movement of particles from an area of greater concentration to lesser concentration. -movement of urea, creatinine, uric acid from patient’s blood into the diasylate. -the diasylate solution contains fewer particles to be removed from the bloodstream and higher concentrations of particles to be added to the blood. *since diasylate contains no protein waste products, the concentration of these substances in the blood will decrease due to random movement of these particles across the semi-permeable membrane into the dialysate. The same with K ions. *RBC and CHON is increased in the blood but they are quite large and do not diffuse through the membrane pores: hence, they are not lost from the blood.

Principles involved in Dialysis: 

OSMOSIS -movement of fluid across a semi-permeable membrane from an area of lesser to an area of greater concentration of particles. -responsible for the movement of extra fluid from the patient. *Glucose is added to the dailysate to make the particles concentration greater than that of the patient’s blood. Fluid will then move through the pores of the membrane from the patient’s blood dialysate.

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ULTRAFILTRATION -movement of fluid across a semi-permeable membrane as a result of an artificially created pressure gradient. -removal of excess water from the patient’s body.

 Involves

shunting the patient’s blood from the body through a machine in which diffusion, osmosis and ultrafiltration occur and back into the patient’s circulation

 Access

to patient’s blood  Requirements to transport the blood to and from the dialyzer  Dialyzer where exchange of fluid, electrolytes and waste products occur

A. External Arterio-venous cannula or shunt  Teflon cannla tips are placed in an artery (usually radial / posterior tibial ) and nearby vein. These cannula tips are connected by a silicone rubber tubing and a teflon bridge to complete the sunt.  It has 9 months life span due to clotting and infection

B. Internal arterio-venous fistula    

Anastomosing an artery directly to a veoin (usually radial artery and cephalic vein at the wrist) Blood is shunted from the artery to the vein causing the vein to enlarge (ripening) after a few weeks. Average life is 4 years; circumvented problems of infection, clotting and possible hemorrhage Disadvantages are painful venipuncture, formation of aneurysms, achieving hemostasis post dialysis and ischemia of the hand.

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A hemodialysis unit's dialysate solution tanks

 Hemodialysis

machine

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Arterial pressure monitor  Locations:  Proximal to the blood pump  

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Function:

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It reads the arterial pressure at the segment between the patient's needle site             and proximal to the blood pump which represent the negative pressure created by the roller pump. It identifies how much suction is being placed on the arterial wall and guard against excessive suction on the vascular access, e.g. .if suddenly the arterial pressure increases from 100 to 200 mmHg this could indicate clotted or dislodged needle, low patient BP or kink in the arterial line. 3. Resistance within the needle (function of the gauge and needle length). 4. It provide an index of vascular access blood supply relative to the flow demand by the blood pump. 5. A guide to appropriatence of needle placement or kink or obstruction in the blood segment between the patient and the monitor. 

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3. 4. 5.

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   Mechanism: The pressure is  monitored by mechanical or electronic manometers (pressure transducers) . Electronic transducer is more sensitive and have rapid response

Temperature 

Location:    Before the dialyzer

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Function:    To avoid high temperature

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Mechanism: Through a temperature sensor, high temperature activate an audiovisual alarm simultaneously with bypass mechanism

Venous air trap and air detector Location: 1. Just distal to venous pressure monitor.  2. Often second air trap on the arterial line is also used. 

Function: To prevent air entry into the patient or to the dialyzer. It is used also to measure the pressure in that segment of blood circuit.

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Mechanism: When air bubbles entered the blood circuit a sensor reacted through ultrasonic transducer or light beam by stopping the blood pump, clamping the venous line, and activating audiovisual alarms.

Coil dialyzer

•Developed by Dr. Willem Kolff.

• First to be mass produced • Cut treatment time to 8-10 hours • A membrane supported by a mesh screen coiled around a central core • Primed with a large amount of blood, set in a holding container called a canister, and bathed with dialysate

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• Sterile and disposable - very costly An early design in which the blood compartment consisted of one or two long membrane tubes placed between support screens and then tightly wound around a plastic core. This design had serious performance limitations, which gradually restricted its use as better designs evolved. The coil design did not produce uniform dialysate flow distribution across the membrane. More efficient devices have replaced the coil design. Basically consists of a flattened cellulose tubing  wrapped as a coil and through which patient’s 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 mounted on plastic support screens, and then stacked in multiple layers ranging from 2 to 20 or more. This design allows multiple parallel blood and dialysate flow channels with a lower resistance to flow. The physical size of the parallel plate dialyzers has been greatly reduced since their introduction. There have been major improvements which provide (1) thinner blood and dialysate channels with uniform dimensions, (2) minimal masking or blocking of membranes on the support, and (3) minimal stretching or deformation of membranes across the supports

Parallel Plate Dialyzer   

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Structure:  -Sheets of membranes 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. Advantages: -Blood volume is about 50-100 ml at 100 mmHg increases with high TMP (bulging sheets) -Heparin requirement usually low, minimal clotting in the blood compartment. -Ulttrfiltration is reasonably predictable and controllable. Disadvantages: -Formation of local thrombi around inlet and outlet ports and corners due to uneven blood flow at these parts. These may lead to bacterial growth and endotoxin formation , therefore plates are not often reused

Measurend record baseline vital signs as weight, temperature, pulse rate, respiration, blood pressure.  Mesure pre treatment result of BUN, creatine, Na, K levels and hematocrit. 

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Sterile technique for needle insertions and shunt connections Anchor connections securely. Check equipment for readiness, safety and gauge settings Monitor vital signs every 15 minutes for 1 hour then every 30 minutes thereafter. Watch out for rapid shifts in volume on electrolytes that my result in hypovolemia, angina, the osmotic gradient produced across the blood-brain barrier by the efficient removal of urea from the blood but not the brain tissues. Urea draws in the water from the ECF and cause cerebral edema.

Measure and record vital signs and weight.  Precaution against infection  Routine care to shunt or fistula  Avoid trauma to sites  Do not use arm with shunt or fistula for blood pressure taking and needlesticks.  Record BUN, creatine Na, K levels to note effects of treatment. 

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follow diet (low Na, low protein) nd fluid restriction Take mediction as ordered Limit weight gain to 0.5 Kg day between treatment Care of access site: a. No BP or IV punctures on arm with shunt/ fistula. b. Cleanse site aseptically w/ peroxide c. Clean shunt w/ alcohol sponges from exit site d. Cover with dry sterile dressing e. Avoid trauma to site, wear loose sleeves, avoid temparature extremes, avoid lifting, heavy objects, avoid prolonged immersion of arm in water

- due to decrease blood flow which results from:

 systemic hypotension  infection of shunt/fistula  compression of shunt/fistula  tight bandages / restricted clothing  phlebitis from puncture of involved veins  prolonged inflation of BP cuff

 absence of palpable or audible bruit along the venous portion of shunt / fistula  presence of dark / separated blood in the tubing

- signs of infection Redness Tenderness Swelling excessive warmth of skin

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Pyrogenic reactions - is a febrile response to infusion of bacteria or bacterial breakdown products

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Bacteremia - is the presence of bacteria in the blood

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Membrane rupture

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Occlusion of hollow fibers

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A catheter is placed in the peritoneal cavity by paracentesis. Two liters of sterile dialysis solution are allowed to run into the peritoneal cavity through the catheter for 10-20 minutes. Equilibrium between the dialysis fluid and the highly vascular semi-permeable peritoneal membrane takes place. The peritoneum acts as the semi-permeable membrane. This is called “dwell time” which is generally 30-45 minutes. The fluid is then allowed to drain by gravity into a closed, sterile connecting system. Cycle is repeated successfully over a period of time.

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simpler, and often as effective, is the technique of peritoneal dialysis, which is essentially a repeated filling and draining off of the abdominal cavity with two or three gallons at a time of a special solution that soaks up harmful metabolites that would otherwise poison the patient. Dr. Belding Scribner of Seattle is prominent in peritoneal dialysis research.

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Simple; does not require highly skilled personnel or sophisticated equipment Does not require access to the bloodstream.

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Requires about 6 times longer than hemodialysis to achieve the same results Often painful especially when increased glucose concentration are used to achieve ultrafiltration. Repeated treatment may lead to peritonitis

1. Continuous Cycling Peritoneal Dialysis (CCPD) -connecting the peritoneal catheter to an automated peritoneal dialysis machine that perform 3-5 cycles during the night while patient sleeps; last bag of solution remains in abdomen during daytime.

2. Continuous Ambulatory Peritoneal Dialysis (CAPD) -a permanent peritoneal dialysis catheter is inserted into the abdomen; a connector joins the transfer set to the bag of the fluid. Plastic bags are use; performs 3-5 exchanges daily; last bag of solution remains in the abdomen overnight.

3. Intermittent Peritoneal Dialysis (IPD) -connected for about 10 hrs, with cycle changing every 30-60 minutes; abdomen is left “dry” between sections.

 Glucose  Sodium

(Na)  Potassium (K)  Calcium (Ca)  Magnesium (Mg)  Chlorine (Cl)  Lactate

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PERITONITIS signs and symptoms: -Abdominal pain -Elevated temperature Intervention: -Aseptic technique, culture and sensitivity of dialysate fluid Antibiotic treatment -Possible removal of catheter

Group members: de Vera, Christine Joy dela Rosa, Mary Jane Fabila, Camille Ferrer, Rodel Flores, Rezza Andrea Gaces, Maria Regina Granado, Neil Bryan Ignacio, Lyra Camille Joniga, Jennalyn Lopez, Jay Mark Madrid, Levin Kim Pabalan, Kenette Lynn