Hemodialysis Machines

GLOSSARY

Kidneys:                                               

The kidneys remove waste products from the blood and produce urine. As blood flows through the kidneys, the kidneys filter waste products, chemicals and unnecessary water from the blood. There are also products that help control blood pressure and regulate the formation of red blood cells.

Dialyzer:                                               
A machine equipped with a semipermeable membrane, which acts as a filter and is used to perform dialysis.
Pressure:                                               

Force exerting a gas, a liquid or a solid on a surface.

Flow:                                                     

Transport of a fluid across a certain area.

DEVELOP 

It is a technique that replaces the main functions of the kidney, by passing the blood through a filter, dialyzer),among these are:

• Facilitate the removal of toxic substances.
• Remove excess fluid accumulated in the body.
• Help control the pressure
• Arterial helps produce red blood cells.

 Figure 1.  Hemodialysis machine

There are two chemical physical processes included in the dialysis process:

1. Diffusion (depuration of solid substances)
2. Osmosis (osmotic ultrafiltration - water removal).

The operation of the hemodialysis machine focuses on the dialyzer that a cylindrical filter consisting of two compartments, the first is internally formed by hollow semi-permeable microporous fibers, where the blood is circulated; and the other compartment is that which is located within the hollow fibers and the walls of the dialyser since the liquid of the dialysis circulates there. In addition, it pumps and controls the blood flow of the patient through the dialyzer at a predetermined speed and pressure to guarantee effective clearances and the elimination of fluids in a specific period of time. Some machines also provide an ultrafiltration rate that measures the ultrafiltration rate in kilograms per hour. This allows the operator to calculate, predict and control fluid removal efficiently and accurately during dialysis.

 Figure 2.  Parts Hemodialysis machine

Figure 2.  Block diagram of hemodialysis machine

Parameters of a hemodialysis machine

1. The Hemodialysis machine must have at least:

   1.1 Volumetric ultrafiltration control.

   1.2 Automatic supply system for the concentrate mixture

   1.3 Ways to visualize hemodialysis parameters

   1.4 Energy requirement with lines to ground

   1.5 Security devices

       - Air intake detector device

       -Devices for pressure monitoring: In the arterial line: pre-pump and in the venous line: post-dialyzer.

       -Device for dialysate monitoring: Temperature, conductivity and for detection of blood leakage.

       -Alarms: all alarms must be visible and audible: Blood pressure, venous and transmembrane, blood leakage. Of the air detector, Conductivity, flow and temperature of the dialysate.

   1.6 The blood lines must be closed automatically if the circuit is interrupted

  1.7 Blood pump: You must have the option of being operated manually, blood flow in the range of 0 to 500 mL / min. 

    1.8 Heparin pump: With programming capability

Maintenance routine

There are preventive maintenance programs, which include detailed equipment examination, physical condition assessment, mechanical tests, calibrations, lubrication adjustments and safety inspections to ensure proper and safe operation. 

a) Daily inspection or each time the equipment is used Visual inspection before each session Procedure for cleaning after each hemodialysis session. 

b) Weekly inspection (or every 100 hours of work) 

c) Bi-monthly inspection. (or every 400 hours of work)

d) Semi-annual inspection (or every 1200 hours of work) 

e) Annual inspection (or every 2400 hours of work general maintenance and change of some components).

SIMULATION

The simulation was developed in the Labview software designed to perform programming by block diagram, in the panel you can see the use of the Roller pump which allows blood and heparin to flow into the dialyzer, without taking into account the control of the amount of blood extracted from the patient in relation to the amount of heparin delivered. Then, go through the bypass where there will be measured the pressure in which the dialysate is. Then in the lower part you can see the indicators of water, concentration and the degree of warming that the filtered blood can have in order to enter the patient again, where there will also be a blood pressure indicator already filtered. Based on the aforementioned, this simulation was implemented a variety of alarms in which they are:

• The one that indicates that the pH value in blood is not within the established range.

• The one that indicates that the quantity of water supplied is not in the established range.

• The one that indicates that the degree of the heater is not in the established range.

• Dialyzer pressure indicator is too high or too low.