Neobook — clinical reference

Dialysis Prescription

Both acute and chronic dialysis procedures must be performed by a dialysis trained nurse or technologist according to the nephrologist’s prescription. Dialysis units not directly supervised by a nephrologist should follow the instructions outlined in section 11 (Supervision of dialysis units).

Dialysis prescription must be adjusted continuously and based on reassessment of a patient’s target metabolic parameters, blood pressure control, fluid balance, decline of residual renal function, dialysis related symptoms, age, weight and vascular access efficiency. Particular attention should be given to the effect of dialysis on other comorbid conditions, like cardiovascular, respiratory, nervous system, and liver disease, etc. The timing of drug administration and dose adjustment should also be reviewed as a part of dialysis prescription.

A typical dialysis prescription should specify the following parameters:

Dialysis frequency per week
Duration of each dialysis session
Mode of dialysis (e.g. convective/hybrid techniques)
Dialysate fluid/concentrate choice based on preferred calcium, potassium and glucose concentrations, and main buffer type
Dialysis filter choice
Vascular access instructions (needle size, catheter pressures, etc.)
Desired blood pump flow range
Other machine-adjustable dialysate parameters: temperature, sodium and bicarbonate concentrations, and modelling programmes
Target dry weight
Ultrafiltration target volume, rate and modelling
Prescribed dose of dialysis (Kt/V per session or weekly)
Target blood pressure range and instructions on management of haemodynamic instability
Management of dialysis-related symptoms
Anticoagulation dose
EPO/ESA and iron administration

Dose of Dialysis

The dialysis team should routinely monitor the delivered dose of haemodialysis using formal urea kinetic modelling, employing the single-pool, variable volume model (Kt/V), or at institutions where this is not possible, the urea reduction ratio (URR).

The dialysis care team should deliver a prescribed HD dose as follows:

Thrice-weekly schedule, with a midweek Kt/V of at least 1.2 or URR of 65% per session.

Note 1:
Twice-weekly schedules are not recommended, unless there is significant residual renal function.

Note 2:
Clinical signs and symptoms alone are not reliable indicators of haemodialysis adequacy, and the delivered dose of haemodialysis should be measured monthly.

Note 3:
To determine Kt/V, blood samples for urea measurement must be drawn at the same HD session, in a specified manner (see K/DOQI guidelines). Where available, online Kt/V can be performed more frequently and requires no consumables for blood draws, but usually requires a more costly machine.

Membranes

Dialyser membranes causing the least complement and leukocyte activation should be used.

Anticoagulation

The use of anticoagulation during haemodialysis is recommended to prevent clotting of the extracorporeal circuit.

For patients with a standard dialysis session of about 4 hours, we recommend an initial bolus of unfractionated heparin of 25 IU/kg followed by a continuous infusion of 1000 IU/hr, to be stopped 30-60 minutes before the end of the session. If the patient routinely requires more than 15 minutes clotting at the needle puncture sites, the maintenance infusion dose should be decreased to 500 IU/hr. (http://ajkdblog. org/2012/06/26/dialysis-and-heparin-whats-the-evidence/)

Note 1:
Options for patients on haemodialysis who are at high risk for bleeding includes no-heparin haemodialysis, minimum dose heparin, and regional anticoagulation with protamine reversal, regional citrate anticoagulation and citrate dialysate. No-heparin and regional citrate anticoagulation are associated with the lowest risks of bleeding, but may have issues with dialyzer clotting. Protamine reversal has been largely abandoned due to its technical difficulties and to problems with rebound bleeding.

Note 2:
Because of the occasional risk of heparin-induced thrombocytopenia, we recommend that platelet counts be checked every 3 months.

Note 3:
Low molecular weight heparins can also be safely used for dialysis anticoagulation.

Dialysate

Bicarbonate-based dialysis is recommended as the treatment of choice.

Water Treatment and Purification

Chronic haemodialysis requires the use of pure water complying at a minimum with the Association for the Advancement of Medical Instrumentation (AAMI) standards that takes into consideration both chemical and microbiological purity. The recommendations of the European Pharmacopoeia are somewhat more stringent. When high flux dialysers or convective therapies like haemodiafiltration are used, ultrapure water should be used.

The recommended maximum limits for dialysis fluid contaminants are listed in the tables below:

Substances with documented toxicity (in mg/L)

Contaminant	AAmi	European Pharmacopoeia
Aluminium	0.01	0.01
Chloramines	0.10
Free chlorine	0.50
Total available chlorine		0.1
Copper	0.10
Fluoride	0.20	0.20
Lead	0.005
Nitra e (as N)	2.00	2.00
Sulphate	100	50
Zinc	0.10	0.10

Substances normally included in dialysate (in mmol/L)

Contaminant	AAmi	European Pharmacopoeia
Calcium	0.05	0.05
Magnesium	0.16	0.16
Potassium	0.20	0.20
Sodium	3.0	3.0

Other substances (in mg/L)

Contaminant	AAmi	European Pharmacopoeia
Ammonia		0.2
Antimony	0.006
Arsenic	0.005
Barium	0.10
Beryllium	0.0004
Cadmium	0.001
Chromium	0.014
Chloride		50
Mercury	0.0002	0.001
Selenium	0.09
Silver	0.005
Thallium	0.002
Total heavy metals		0.10

	Bacteria (CFU/mL)	Endotoxin (EU/mL)
AAMI	200	2
European Pharmacopoeia	100	0.25
European Pharmacopoeia UPW*	0.1	0.03

= ultrapure water

Note 1:
Pure water is the basic form of treated water that is suitable for conventional haemodialysis modalities. Purified water is obtained from a purification system consisting of pre-treatment (softener, activated carbon, micro-filters), and a reverse osmosis (RO) unit, implemented in series.

Note 2:
Regular and effective disinfection procedures are an integral part of the hygienic maintenance of the water treatment system (including RO and/or deioniser, and distribution loop) and should be performed at least once per month.

Note 3:
Monitoring of chemical contaminants should be done 3-monthly, and measurement of bacterial counts and endotoxin levels done monthly.

(Ward RA. Worldwide water standards for haemodialysis. Haemodialysis International 2007; 11(s1): S18-S25)

Reprocessing of Dialysers

The reuse of dialysers is practiced in some South African settings. The AAMI recommendations for reprocessing should be followed.

Note 1:
Patients should be informed that reuse is being practiced and staff should be vigilant for any complications that could be due to reprocessed dialysers.

Note 2:
Patients with following conditions should be excluded from re-use: sepsis, acute hepatitis, hepatitis B and hepatitis C infection, HIV infection.

Note 3:
Reprocessed dialysers must be used on the same patient; labelling must identify the patient and include pertinent information about the reprocessing procedure.

Note 4:
Water for reuse procedures should meet the same standards as water for dialysis.

Note 5:
Peracetic acid or heated citric acids are the preferred sterilants.

Note 6:
Haemodialyser performance and the delivered dose of dialysis may decline as a result of dialyser reuse. The total cell volume (TCV) of reused dialysers should be monitored and those having a TCV <80% of the original measured value should be discarded.

Note 7:
The environmental load resulting from the reprocessing chemicals vs. that of discarded (single use) dialyzers needs to be considered. Adequate ventilation should be ensured in areas where reprocessing of dialysers is performed using noxious chemicals.

(Reuse of Hemodialyzers: ANSI/AAMI RD47, Washington, DC, American National Standards Institute 2002 and UpadhyayA, Sosa MA, Jaber BL. Single-use versus reusable dialyzers: the known unknowns. Clinical Journal of the American Society of Nephrology 2007; 2(5): 1079-1086).

Click here for the pdf.

Paget G, Naicker S, et al. Guideline for the optimal care of patients on chronic dialysis in South Africa. South African Renal Society; 2015.

Haemodialysis Procedures