Submitted by Dr YAN Wing Wa and Dr LAU Chun Wing Arthur on 15 March 2009
Department of Intensive Care, PYNEH
|
|
What are those little metal bars sticking out of these infusion pumps?
Answer: Equipotential terminal
Equipotential (EP) point of a syringe pump is used to connect to the EP earthing system of a cardiac protective area.
The EP Earthing system requires all earthed points of equipment and any other exposed metal within the cardiac protected area to be connected back to a common EP Junction via low resistance earth wiring (EP bus). The low resistance system reduces the potential difference between two earthed points in the area therefore reducing the risk of micro electrocution from the stray currents flowing in the earthing system. The micro electrocution is possible when electrical conductors such as cardiac pacing wire, intracardiac ECG leads or electrolytes filled intracardiac catheters are in contact or in vicinity of heart.
Area Classification & Requirements
Medical treatment areas can be divided into the following three categories:
1. UNPROTECTED AREA
If procedures do not require the physical attachment of electro-medical equipment to the patient, electrical safety in such areas typically involves nothing more than normal domestic or industrial wiring practices. The area in this case is known as an ‘Unprotected Area’.
2. BODY PROTECTED AREA
Where electro-medical equipment is attached to external parts of the body so that contact resistance is reduced and ready disconnection is also not possible, Body Area Protection is required. Examples of areas and procedures that may require this type of protection are ECG, EMG, EEG, and Physiotherapy rooms, plus any room used for dialysis.
A Body Protected Area requires mainly the installation of Residual Current Devices (RCDs) or Line Isolation and Overload Monitors (LIOMs).
3. CARDIAC PROTECTED AREA
Where electro-medical equipment is in close contact with the heart, Cardiac Area Protection is required. Examples of areas and procedures that may require this type of protection include CCU, ICU, and operating theatres where cardiac procedures are performed. A Cardiac Protected Area requires firstly RCD and/or LIOM protection as per Body Protected Areas, and secondly an Equipotential Earthing System.
Reference
Australian and New Zealand Standards (AS/NZS)3003 “Electrical Installations – Patient treatment areas of hospitals and medical and dental practices”.