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Monday, October 3, 2011

#28 - Ambient Oxygen Monitoring in MRI Suites

We have had a number of inquiries over the years for gas analyzers for use in hospitals. We do not address the medical market per se. For example, we do not manufacture blood gas analyzers or medical gas purity analyzers. Our primary market is in the industrial and recovered gas industries.

One common application in industry is ambient air monitoring. We have noted that some non-industrial markets have also successfully used our ambient air monitors. One example is oxygen deficiency monitoring in MRI suites.

Apparently, MRI machines are cooled to a specific operating temperature using a large quantity of helium gas. There may be up to 1,000 liters of liquid helium contained in a cryostat at approximately -267°C (450°F). In the event of a leak, the liquid helium will evaporate and flood the MRI room helium gas. The gas itself is not immediately toxic, but the resulting oxygen displacement is very dangerous. The patient in the MRI machine, who may or may not be sedated, could be unaware of the onset of asphyxiation.

According to OSHA (Occupational Safety & Health Administration) in the USA, “OSHA uses the term "asphyxiating atmosphere" when referring to an atmosphere which contains less than 19.5 percent oxygen. Oxygen levels under 19.5 percent are inadequate for an entrant's respiratory needs when performing physical work, even if the space contains no toxic materials.”

An additional concern is that the door between the MRI unit and the control room is frequently sound-proof. A sedated or oxygen-deficient patient may have difficulty signaling to the technicians that there is a problem.

Additionally, during evaporation, the liquid helium undergoes a rapid thermal expansion which temporarily pressurizes the room. If the door opens into the MRI room, outside staff would be unable to open the door.

The Nova Model 510D is an oxygen deficiency monitor with a diffusion-style electrochemical sensor. There are two levels of alarm:

1. Alert level at 19.5% O2 which triggers a yellow LED light, an optional flashing red strobe light, and a relay contact.

2. Alarm level at 18.0% O2 which triggers a red LED light, an audible horn, an optional flashing red strobe light, and a relay contact. The audible horn may be silenced using an acknowledge button.

There are various configurations are available to suit different monitoring schemas as shown in the above graphic. Here is the brochure in our on-line catalog…

We make industrial gas analyzers for oxygen, hydrogen, carbon monoxide, carbon dioxide, methane, and many other atmospheric gases. We provide gas analysers for syngas, landfill gas, purity gas, biogas, and others. We also do ambient air and oxygen deficiency monitoring.

Give Mike or Dave at Nova a call, or send us an e-mail.
sales at nova-gas dot com
websales at nova-gas dot com
If you have a LinkedIn account, search for Nova Analytical Systems under Companies and follow us if you want.

Record Type: Permit-Required Confined Spaces, Section: 2, Title: Section 2 - II. Hazards, Footnote (1) a.

Pic of MRI Copyright 2010 Viet-Can Medical Services

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