PRINCIPLES OF DIALYSIS DR SAAD ALSHOHAIB ASSOCIATE PROFESSOR IN

MEDICINE AND NEPHROLOGY KAUH

Dialysis in Saudi Arabia

There are 6700 patients on dialysis in Saudi Arabia

There is 130 haemodialysis centres in Saudi Arabia

The incidence of hepatitis B is 6.7%and 50% for HCV

SCOT data Saudi J kid 2001 12 (3)

Dialysis in the Kingdom

It had been estimated that the number of dialysis patients would exceed 10000 patients in the year 2010

Most centres are saturated and need to expand in order to accept new patients

There is a great need for CAPD in Saudi Arabia

SCOT data Saudi J kid 2001 12 (3)

Principles of dialysis

The exchange will depend on

Concentration Size and binding Speed Membranes pores Time pressure

Dialysate

Treated water is mixed with an electrolyte solution

Na 135---145 K 0 -- 4 Ca variable HCO 3 35 Mg .5-- 1

MEMBRANES

Cellulose Substituted cellulose ( acetate ) Cellulose synthetic ( amino group added ) Synthetic (PAN polysulfone )

COMPLEMENT

Cellulose membranes activate complement and this reduced by using more compatible membranes

prescription

Blood flow Time Membrane type Fluid removal Electrolytes

DRY WEIGHT

WELL KNOWN CONCEPT BUT MANY PITTFALLS WITH PRACTICAL APPLICATION

LOW DRY WT LEAD TO FATIGUE WEAKNESS AND LETHARGY

HIGH DRY WT LEAD TO HYPERTENSION

DRY WEIGHT

When patient appetite improve with adequate dialysis their weight improve then tend to be hypotensive

Inadequate dialysis lead to decreased appetite and loss of wt these patients present with sever hypertension and possibly pulmonary edema

Patient may share in the decision of the dry wt

Hypertension and dry wt

Hypertension is mostly volume related Hypertension at the beginning of dialysis and

improving toward the end is usually volume dependent and respond to fluid removal

Hypertension at the end of dialysis may respond to ACE inhibitors

Adequacy

Kt/v is a good marker but not the only one Monitor the phosphate PTH serum albumin

BUN Cr and Hgb The wellbeing of the patient and his general

condition and ability to perform activity are important markers of adequate dialysis

Good appetite and nutrition are important markers

Chronic dialysis prescription

Prescription should be individualized according to patient weight sex age and residual renal function

Cardiac status is important in determining blood flow

Choice of membrane would depend on the facilities expertise and availability of support services

Predialysis urea

Value higher than expected

Increased protein intake

G I bleed Decreased residual

renal function Decreased dialysis

efficiency

Value lower than expected

Malnutrition Chronic illness Liver disease Wrong sampling

Prognosis

Good prognosis Cholesterol value 200

—250 Being obese Normal albumin Adequate dialysis

Bad prognosis Very low urea an Cr Low albumin Low K Low cholesterol High PTH and P Old age DM

Anticoagulation

Heparin is usually used to maintain an ACT of 1.5 -- 1.8

Heparin is usually as a bolus followed by infusion

Stop heparin at the last hour of dialysis Contraindications include pericarditis recent

surgery active bleeding and thrombocytopenia

Hypotension during dialysis

High UF rate Fluctuation in UF rate Dry weight set too low Low dialysis Na Warm dialysis solution Food ingestion Diabetic neuropathy Antihypertensive meds Poor cardiac status

Hypotension prevention

Decrease intradialytic weight gain Adjust dry weight Keep dialysate Na at or above serum value No antihypertensive before dialysis May need to avoid feeding certain patients on

dialysis

CRF

There are three types of access for dialysis AV fistula Graft Central line

TIMING OF ACCESS PLACEMENT –A. Patients with chronic kidney disease should be referred for surgery to attempt construction of a primary AV fistula when their creatinine clearance is <25 mL/min, their serum creatinine level is >4 mg/dL, or within 1 year of an anticipated needfor dialysis.

B. A new primary fistula should be allowed to mature for at least 1 month,and ideally for 3 to 4 months, prior to cannulation. ()

C. Dialysis AV grafts should be placed at least 3 to 6 weeks prior to ananticipated need for hemodialysis in patients who are not candidatesfor primary AV fistulae. (

D. Hemodialysis catheters should not be inserted until hemodialysis is needed.

DIAGNOSTIC EVALUATION PRIOR TO PERMANENT ACCESS SELECTION –A. Venography prior to placement of access is indicatedin patients with the following: 1. Edema in the extremity in which an access site is planned 2. Collateral vein development in any planned access site 3. Differential extremity size, if that extremity is contemplated as an access site 4. Current or previous subclavian catheter placement of any type in venous drainage of planned access ) 5. Current or previous transvenous pacemaker in venous drainage of planned access ) 6. Previous arm, neck, or chest trauma or surgery in venous drainage of planned access ) 7. Multiple previous accesses in an extremity planned as an access site

SELECTION OF PERMANENT VASCULAR ACCESS ANDORDER OF PREFERENCE FOR PLACEMENT OF AVFISTULAE –

A. The order of preference for placement of AV fistulae in patientswith kidney failure who will become hemodialysis dependent is:

1. A wrist (radial-cephalic) primary AV fistula

2. An elbow (brachial-cephalic) primary AV fistula )

B. If it is not possible to establish either of these types of fistula, access maybe established using: 1. An arteriovenous graft of synthetic material (eg, PTFE) ( or 2. A transposed brachial basilic vein fistula )

Wrist (radial-cephalic) and elbow (brachial-cephalic) primary fistulae are the preferred typesof access because of the followingcharacteristics:A. Excellent patency once established

B. Lower complication rates compared to otheraccess options including lower incidence ofconduit stenosis, infection, and vascular stealphenomenon

C. Lower morbidity associated with their creation

D. Improved performance (ie, flow) over time

Dialysis AV grafts have the following advantages:

A. Large surface area available for cannulation

B. Technically easy to cannulate

C. Short lag-time from insertion to maturation

PTFE dialysis AV grafts should not routinely beused until 14 days after placement. Cannulation ofa new PTFE dialysis AV graft should not routinelybe attempted, even 14 days or longer afterplacement, until swelling has gone down enough toallow palpation of the course of the graft. Ideally, 3to 6 weeks should be allowed prior to cannulationof a new graft. (Opinion)

Improving patient lifetime on therapy

Access Adequacy

NutritionCompliance

QoL

Infection control

Complications of Renal Failure

Hypertension Sodium Retention/Fluid Accumulation Anemia Dyspnoea Electrolyte Imbalance Acidosis Uraemic Syndrome

Uraemic Syndrome Loss of Appetite Nausea Change in Taste Fatigue Sleep Disorders Mental Changes Neuropathy Anemia Itching Acidosis Shortness of Breath

Withdrawal or No Treatment

Some patients may not be able to psychologically accept dialysis.

An elderly patient with co-morbid conditions may not be accepted for therapy.

Medical conditions may preclude therapy. Medical team, patient and patient family will

discuss treatment alternatives.