Monoplace Delivery System

Monthly Hyperbaric Safety Notice: February 2007

Use of Rubber-Based Products in Oxygen-Filled Hyperbaric Chambers

Background

Several rubber-based products are in common use in the monoplace hyperbaric chamber. They include the anesthesia bag used for air break exchange on the patient ventilator breathing circuit, the Scott air break face mask assembly, and bladder and tubing within the CAS blood pressure cuffs.

The Issue

All materials exposed to oxygen oxidize (deteriorate) over time. The rate of oxidization increases as oxygen time and oxygen pressure increases. Hyperbaric oxygen exposure compounds the deterioration rate. Rubber is a valuable industrial material that is resilient, strong and wear resistant. Its drawback, however, is that it is poorly resistant to certain environments and chemical agents, oxygen being one of them. As is noted in NFPA 99 Chapter 20, 2005 “Materials containing rubber deteriorate rapidly in oxygen-enriched atmospheres” (A20.3.6.2.4)

It is important, therefore, that extra attention be focused on the inspection of all rubber and rubber-based items used in the hyperbaric chamber. We have seen evidence of this degree of deterioration in the tubing of the HBO NIBP where a small hole had worn through and was determined to be the source of the ‘Air Leak’ alarm.

Bottom Line

Careful inspection of all rubber and rubber-based items is necessary. The anesthesia bag should be replaced at least every two years as a minimum, and more frequently if indicated. Please review the revised ‘Monthly Unit Inspection Form’, now loaded onto the NBS intranet.

In addition, small cracks in porous materials, such as deteriorating rubber tubing, can harbor bacteria. Extra care should be taken, therefore, when disinfecting. (Refer to the NBS infection policy for proper cleaning; C-4).

Contributing Author: Dick Clarke, CHT

Dick Clarke Dick 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.

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