We comply with the HONcode standard for trustworthy health
information:
verify here.


MedEdOnline
Five Richland Medical Park
Columbia, SC 29203
USA
Phone: +1.803.434.7101
Fax: +1.803.434.4354
 

Monoplace Delivery System

Monthly Hyperbaric Safety Notice: June  2006

Oxygen Analyzer Sensor

Background  

An "in-line" oxygen analyzer is required whenever more than one gas is designed to supply a particular line. This will allow a constant and real-time indication of whether oxygen or air is being provided to the patient (directly, in the case of an "air break" device, or indirectly in the case of the hyperbaric ventilator).

The Issue  

The purpose of this Notice is to describe the operation and replacement requirement of the oxygen sensor (such as in the commonly used MiniOx 1). It is the sensor that "drives" the oxygen recording process. It operates in a similar manner to the transcutaneous oxygen monitor. An anode and cathode are enclosed within the sensor. They produce an electrical current when in contact with oxygen, and this current is proportional to the oxygen concentration (usually 100% and 21% in our setting).

When in constant operation the sensor has a life span of one year. When turned off between use, the sensor's life increases accordingly. If the sensor membrane remains exposed to the atmosphere, it will continue to use up its available operating life, even when the monitor is turned off, although at a slower rate. One can normally expect a useful life of 18-24 months when used in conjunction with the monoplace chamber.

How do you know when it is no longer functional? When it is no longer possible to calibrate the monitor and the nine volt battery is in good working order.

If the sensor is failing, the oxygen percentage will read less than 21%, even when the calibration dial is turned entirely clockwise.

Bottom Line  

When the oxygen monitor will not calibrate three possible problems exist. Commonly, it is the battery in need of replacement. If this does not correct the problem it will almost certainly be a sensor problem. Replace the sensor and proceed with monitor calibration.

A good idea is to mark the month/year that a new sensor is installed on the sensor with an indelible marker. If a new sensor does not correct the problem the monitor is in need of factory service, or replacement.

Contributing Author: Dick Clarke, CHT

Dick ClarkeDick is President of National Baromedical Services, which he founded in 1986. His previous background included service in the British Royal Navy, diving instructor and underwater photographer, assistant director of the seabed habitat 'HydroLab' and several years in the offshore commercial diving industry. Dick heads the Baromedical Research Foundation where he serves as Principal Investigator for several international clinical trials. He is course director for 'Primary Training in Hyperbaric Medicine' and the 'HBO 2000' series of advanced hyperbaric symposia. Dick has been a NOAA Diving Medical Officer Training Course faculty member since 1983. He pioneered the Certification in Hyperbaric Technology (CHT) program, is a past president of the National Board of Diving and Hyperbaric Medical Technology and remains active at the committee level within the Undersea and Hyperbaric Medical Society.

Full Panel of Safety and Technical Correspondents

Previous Monoplace Safety Notices: