CRF and DialysisDarya OsmanEman Salah Moaz AhmedManal Balla

Quick Overview of CRF

Usually asymptomatic until advanced stages

Usually detected at earlier stage by blood and urine test

Common in individuals with: HTN DM Family history of CKD

Early Renal Disease – Renal Insufficiency

End Stage Renal Disease – Renal Failure

Indications for Dialysis

Should be started when benefit of relieving uremic signs and symptoms outweighs risk and decrease in quality of life

Indications vary for acute and chronic kidney injury

Dialysis indications for ARF Think AEIOU

Acidemia – from metabolic acidosis

Electrolyte abnormality e.g. severe hyperkalemia

Intoxication acute poisoning with dialyzable SLIME substances (i.e. Salicylic acid,

Lithium, Isopropanol, Mg containing laxatives and Ethylene glycol)

Overload of fluid

Uremia complications e.g. pericarditis, encephalopathy or GI bleeding

Dialysis indications for CRF Indicated when patient has symptomatic kidney failure and low

glomerular filtration rate

Studies found that early start of dialysis may be harmful

Recently guidelines recommend deferring dialysis until a patient has definite kidney failure symptoms (i.e. those that occur at GFR of 5-9ml/min/1.732)

May also be indicated if there is difficulty to medially control fluid overload or serum potassium level

If symptoms of Intractable kidney failure may start dialysis at eGFR levels above 10ml/min/1.732

General Principles of Dialysis

Works on the principles of diffusion and ultrafiltration of fluid across a semi-permeable membrane.

Diffusion: movement of solute across semi- permeable membrane from region of high concentration to low concentration

Ultrafiltration: water is driven by either a hydrostatic or an osmotic force is pushes through the membrane.

Principle of Dialysis

Blood flows by one side of a semi-permeable membrane and a dialysate (special dialysis fluid) flows by the opposite side

Semipermeable membrane contains pores of various sizes

Smaller solutes and fluid pass through membrane but large substances do not (e.g. RBCs, large proteins)

Replicates filtering process of the glomerulus of the kidney

Goal of Dialysis

Solute clearance Diffusive transport (based on counter current

flow of blood and dialysate) Conventional transport (solvent drag with

ultrafiltration)

Fluid removal

Types of Dialysis

Haemodialysis

Peritoneal Dialysis

Hemofiltration

Hemodialysis

Waste products are filtered from blood by a semi-permeable membrane and removed by the dialysis fluid, or dialysate.

In-center: 4 hours, 3 days a week

Home: Daily

Nocturnal In-centre: 6-8 hours, 3nights/week

Types of Hemodialysis

In center dialysis

Home haemodialysis

In centre nocturnal dialysis

Dialysate Composition

Varies according to clinical need

Major/Common components: High purified water Sodium Potassium Calcium Magnesium Chloride Bicarbonate dextrose

Access for Hemodialysis

Arteriovenous Fistula

Arteriovenous Graft

Central Venous Catheter

Arteriovenous Fistula

Preferred form of dialysis access

once the fistula properly matures and gets bigger and stronger; it provides an access with good blood flow that can last for decades.

Types: Radiocephalic (first choice) Brachiocephalic (second choice) Brachiobasilic (thirs choice, requires superficialization of basilic

vein,i.e. Transposition)

Arteriovenous Graft

Placed between an artery and a vein

Either straight or looped

Common sites: Radial artery to cephalic vein Brachial artery to cephalic vein Brachial artery to axillary vein Axillary artery to axillary vein

Central venous catheters

Aka cuffed dialysis catheter Most commonly placed in the internal jugular Vein, existing at

the upper, anterior chest. Can also be placed in the femoral vein. Subclavian catheters should be avoided due to risk of subclavian

stenosis. ADV: no need for fistula. DIS ADV: short period use, infection, thrombosis, inadequate

blood flow and overall increased risk of mortality.

Peritoneal Dialysis

Use of peritoneal membrane as a filter to clear wastes and extra fluid from the body and to return electrolyte levels to normal.

Peritoneal cavity: reservoir for dialysate (sodium, chloride, lactate and glucose)

Peritoneum: semi- permeable membrane across which excess body fluid and solutes are removed (fluid, urea, creatinine and potassium)

Peritoneal Dialysis

Types of Peritoneal Dialysis

Continuous ambulatory PD: 4-8 hours 4 times/day

Automated PD: Continuous cycling once a day

PD Transport

Diffusion

Ultra-filtration

Absorption

Advantages of Haemodialysis vs. Peritoneal dialysisHaemodialysis Done by trained health

professionals who can watch for any problems.

Allows contact with other people having dialysis, which may give you emotional support.

Not done by oneself, as with peritoneal dialysis.

Done for shorter amount of time and on fewer days each week than peritoneal dialysis.

Peritoneal dialysis Gives you more freedom than

hemodialysis. Can be done at home. You can do it when you travel. You may be able to do it while

you sleep. You can do it by yourself. It doesn't require as many food and

fluid restrictions as hemodialysis. It doesn't use needles. 

Disadvantages of Hemodialysis vs. Peritoneal dialysisHemodialysis Causes feeling of tiredness on

the day of dialysis. Can cause problems such as

low blood pressure and blood clots in the dialysis access.

It increases your risk of bloodstream infections.

Peritoneal diaysis Procedure may be hard for some

people to do. Increases risk for an infection of

the lining of the belly, called peritonitis.

Hemofiltration

Based on convective transport rather than diffusion to remove solutes from blood of uremic patients

Requires no dialysate, however require substitution fluid

Positive hydrostatic pressure drives water and solutes get dragged along the flow of water

Sometimes used in combination with hemodialysis

Usually used for ARF and sepsis

Types of hemofiltration

On-line intermittent hemofiltration (IHF) or hemodiafiltration (IHDF)

Continuous hemofiltration (CHF) or hemodiafiltration (CHDF)

On-line intermittent hemofiltration (IHF) or hemodiafiltration (IHDF)

Given in outpatient dialysis units 3 or 4 times per week 3 – 5 hours per treatment

Substitution fluid is prepared on-line from dialysis solution

Solution is run through two sets of membranes to purify it before infusing directly into blood line.

Continuous hemofiltration (CHF) or hemodiafiltration (CHDF)

Used as treatment for fluid overload

Treatment usually 8 – 12 hours (SLEF – Slow Extended Hemofiltration)

A.K.A. continuous veno-venous hemofiltration

No on-line creation of replacement fluid from dialysis solution

Native hemodialysis access (i.e. fistulas or grafts) are unsuitable because of prolonged residence of access needles required might damage accesses

Advantages of Hemofiltration  Convection overcomes reduced removal rate of larger solutes (due to slow

speed of diffusion)

Characterized by increased solute removal capabilities for higher MW solutes

More similar to glomeruli in the function of filtration.

More suitable than Hemodialysis to some symptoms Resistant Hypertension Water Retention, Hypertension Heart Failure caused by high blood volume, Uremic Pericarditis, Acute Renal Failure Hepatic Coma.

Disadvantages of Hemofiltration price is higher than Hemodialysis due to the need of

plentiful placement fluid

Blood pressure during Hemofiltration is not easy to control and low pressure and high pressure may occur if the volume is in imbalance.

The small products may be not removed as effectively as Hemodialysis.

Therefore, which dialysis to choose depends on each patient’s individual condition

Thank you!