About hemodialysis device security design (1)

Hemodialysis therapy for renal failure patients for new treatments.

Currently, hemodialysis therapy is the most widely used at home and abroad for the treatment of renal failure, but by their treating object for the treatment of critically ill patients and high risk, that any one small failures are likely to cause serious malpractice, hemodialysis device requires extremely high security. This article in accordance with the characteristics of hemodialysis equipment from electrical safety and function of the safety aspects of their security requirements.

First, the electrical safety requirements

Hemodialysis unit mainly consists of power supply parts, heater, motor, temperature sensor, pressure sensor, the conductivity sensor, etc, according to the requirements of GB9706.1-1995 involving electrical safety is a broad category, but easy to cause harm to patients mainly on two aspects: shockproof and leakage current.

This section uses a specific products insulated figure, on the patients with shockproof and leakage current of these two critical issues. Figure 1 typical hemodialysis device insulation diagram (figure 1 Typical insulation of haemodialysis equipment)

　　

1. application part types determine

Hemodialysis device in a treatment plant through dialysis fluid and blood contact, according to the conventional medical electrical equipment design idea, or directly to the heart and blood contact part of the application, the application should be part of the design into CF, but all of hemodialysis equipment application parts are B-type, this is its special structure determines, at this stage, it also does not have the ability to design a CF structure.

In accordance with the application part of the function is defined, the device must be running and patient contact parts.

In dialysis unit operation, dialysis fluid through a semi-permeable membrane and blood for substance Exchange, semipermeable membrane is no any effect of isolation, so that the entire running dialysis solution should be considered as part of the application in part, this includes dialysis fluid dispensing system, temperature sensors, dialysis fluid pressure sensor, the conductivity sensor and heater, etc. These heaters are the protection of ground parts that determine blood dialysis unit can provide basic shockproof capacity and leakage current protective effect of a specific, hemodialysis device application part for B-type application part.

2. the electrical part of shockproof analysis

Figure 1 shows, from the external power supply to the patient, there are four ways through various insulation reaches the application part.

One is from the net power through intermediate circuit, and through a variety of sensors and dialysis fluid contact; the second is from the net power through the heater and dialysis fluid contact; 3 batteries (battery can be viewed as specific mains) through an intermediate circuits across a wide variety of sensor and dialysis fluid exposure; (4) external power to the various uncertainties could through SIP/SOP interface, across the Middle circuit and contact with the sensor and the dialysis fluid. Following on, as shown in Figure 1 points a to G of the above four approaches for analysis.

A network of power through the intermediary) circuit for patients