CHBT Electrical Safety and Biomedical Engineering Principles

Question 1

What is the maximum allowable leakage current for patient-connected medical equipment according to AAMI/IEC standards?

Accepted Answer

100 microamperes

Answer

AAMI/IEC 60601-1 sets 100 microamperes (0.1 mA) as the maximum allowable patient leakage current for Type B applied parts under normal conditions.

Question 2

Which type of grounding system is specifically required for patient care areas in dialysis units to minimize electrical hazards?

Accepted Answer

Isolated power system

Answer

Isolated power systems (IPS) are required in critical care patient areas including dialysis to prevent ground fault currents from passing through the patient.

Question 3

In the context of hemodialysis equipment, what does 'macroshock' refer to?

Accepted Answer

Current above 1 mA applied to the skin surface

Answer

Macroshock refers to currents above approximately 1 mA that are perceptible at the skin surface and can cause muscle contraction, respiratory arrest, or ventricular fibrillation at higher levels.

Question 4

What is the primary purpose of a line isolation monitor (LIM) in a dialysis unit?

Accepted Answer

To detect loss of isolation in an isolated power system

Answer

A line isolation monitor continuously measures the impedance between the isolated power lines and ground, alarming when the fault hazard current exceeds safe limits (typically 2 mA or 5 mA).

Question 5

Which class of medical electrical equipment relies solely on basic insulation for patient protection with NO protective earth connection?

Accepted Answer

Class II

Answer

Class II equipment (double-insulated) uses reinforced or double insulation rather than a protective earth connection to protect against electric shock.

CHBT - Certified Hemodialysis Bio-Medical Technician Practice Test

CHBT - Certified Hemodialysis Bio-Medical Technician Practice Test

CHBT Electrical Safety and Biomedical Engineering Principles