After years of neglect, this fascinating topic has finally founds its way into the fellowship exam in the form of Question 22 from the first paper of 2016.
Microshock: small current delivered via electrodes directly into the body, bypassing the resistance of the poorly conductive skin.
Equipotential earthing
- Ensures all equipment is earthed at the same low potential
- Red sockets
Residual current devices (RCDs)
- Detect current leak
- Breaks circuit if the leak is detected
Line isolation monitors (LIMs)
- Monitor escess current
- Alarm when excess current detected
Uninterruptible power supply
- Connected to battery banks or diesel generator.
- Blue sockets
Protected areas:
- Cardiac protected electrical area
- Areas where microshock is likely, eg. areas where patients have intravascular devices
- These areas have equipotential earthing and RCDs/LIMs
- Body protected electrical area
- Areas where microshock is unlikely (eg. outpatient clinics, anywhere there is ECG monitoring)
- RCDs/LIMs are used
Equipment electical safety is classified by the permitted current leak:
- Type B devices can leak all they want
- Type BF devices can only leak a maximum of 5mA
- Type CF devices can only leak a maximum of 50μA
References
O'HARA Jr, JEROME F., and THOMAS L. HIGGINS. "Total electrical power failure in a cardiothoracic intensive care unit." Critical care medicine 20.6 (1992): 840-845.
NASEERUDDIN, ENGR SM. "ELECTRICAL SAFETY IN HEALTHCARE FACITILIES." (2004).
Olson, Walter H. "Electrical safety." Medical instrumentation. Boston: Houghton Mifflin Co (1978): 667-707.
Χριστοδούλου, Χριστόφορος. Recommendations and standards for building and testing an Intensive Care Unit (ICU) electrical installation. Diss. 2011. - This is a fascinating masters thesis dissertation on the standards of electrical equipment in ICU. It is not exactly a canonical source- as I expect the CICM engineers use other, locally validated guidelines -but it is an interesting read nonetheless, particularly because the author makes his recommendations on the basis of published evidence. Thus, this is the nearest thing I can find to "evidence-based ICU design".