Nitrogen Distribution Systems
Hazard [Health Devices Feb 1989;18(2):85]
A member hospital reported that after installation of a new anesthesia
machine equipped to use oxygen, nitrous oxide, and air, pre-use tests of the unit produced
no airflow through the unit until one of the OR personnel turned on the regulator on a
wall-mounted nitrogen control panel installed for the use of nitrogen-powered tools. What
appeared to be airflow was then determined to be nitrogen. Delivery of such a hypoxic gas
component to a patient would be a serious risk.
The nitrogen panel controlled the distribution of nitrogen to a ceiling
track assembly fitted with nitrogen delivery hoses. Both the nitrogen panel and its hoses
were fitted with a specific brand of air fittings.
When the system was installed, the panel manufacturer offered a choice of
DISS nitrogen and two brand-name fittings. The hospital's existing anesthesia units did
not use air and consequently had no air inlet fittings that might permit misconnection to
a nitrogen outlet. Therefore, because there were no quick-connect brand-name nitrogen
fittings available at the time, the hospital chose to use quick-connect brand-name air
fittings in the nitrogen system.
Hospitals should update systems with proper gas-specific wall, hose, and
equipment fittings to prevent nitrogen/air misconnections.
- Inspect all high-pressure nitrogen systems to be
sure they have only nitrogen-specific fittings. Compressed air fittings
marked for nitrogen are still unsafe because they can be misconnected
accidentally. Include in your inspection all wall or ceiling outlets, hoses
(both ends), and equipment to which these supplies may be connected. Replace
any inappropriate fittings with those that are nitrogen-specific. We
recommend DISS fittings, but some users prefer quick-connect fittings for
the tool itself. Even if connector-equipment mismatches are unlikely now,
they are likely to be a problem in the future.
- Until new fittings can be installed, tag affected
outlets and units to alert users to possible misconnection.
- Inspect all gas systems at the time of installation, following repairs,
and periodically. (See Health Devices Inspection and Preventive Maintenance System
procedure for Medical Gas/Vacuum Systems (440-595).
- Fittings/Adapters, Pneumatic, Quick Connect
Cause of Device-Related Incident
Device factors: Device interaction; Improper
maintenance, testing, repair, or lack or failure of incoming inspection
User errors: Accidental misconnections;
Failure to perform pre-use inspection; Improper connection
External factors: Medical gas and vacuum supplies; Power supply
Support system failure: Lack or failure of
incoming and pre-use inspections
Mechanism of Injury or Death
Overdose; Suffocation; Underdose; Wrong drug