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
 

Multiplace Delivery System

Monthly Hyperbaric Safety Notice: January  2006

Choosing equipment for safe use inside the multiplace chamber

In this notice, factors will be discussed that are essential to the safe selection of equipment to be used inside a multiplace hyperbaric chamber.

Background
Special considerations are required when selecting any piece of equipment to use in a hyperbaric environment, whether 21 percent oxygen (multiplace) or 100 percent oxygen (monoplace). The chamber’s atmosphere must be free from toxic fumes and items that may cause an ignition source. Equipment considered hazardous under hyperbaric conditions must not be allowed inside the chamber. The methods for safely using equipment inside a multiplace chamber remain the decision of each hyperbaric facility’s designated Safety Director.

Safety Issue
Written documents should always be available that verify the safety of any piece of equipment being used inside a multiplace hyperbaric chamber. Established policies for all hyperbaric equipment must exist. Equipment related policies include but are not limited to, testing equipment pressure, utilizing equipment, placing equipment out-of-service and returning it to service, and what to do if a piece of equipment fails during a treatment.

The American Society for Testing and Materials (ASTM) developed guidelines for selecting materials considered safe to use in oxygen equipment and components for oxygen systems. The Navy's Experimental Diving Unit established a Clinical Hyperbaric Evaluation and Testing (CHET) program to evaluate the performance and safety of equipment used inside the chamber. The testing used in this program was created to ensure that any item entering a clinical hyperbaric chamber was not toxic,explosive, flammable, pressure intolerant, and to confirm the equipment’s compatibility with oxygen. In addition to the Navy's evaluation efforts, a wealth of information is available from the UHMS and within its membership, committees, databases, and publications. Contacting colleagues can also prove valuable when researching equipment. The majority of staff at well-established hyperbaric facilities are most willing to provide their own experience(s) with various products and equipment. Nobody wants an accident to occur; one major accident will affect the entire hyperbaric field.

One of the most common pieces of biomedical equipment used inside multiplace hyperbaric chambers is an infusion pump for administrating intravenous venous fluids. There are several types used throughout clinical hyperbaric settings. In the multiplace environment, infusion pumps can be located either outside or inside the chamber. Using an approved and tested infusion pump outside a multiplace chamber works in the same manner as with a monoplace chamber. Pumps used inside the chamber must be tested for gas trapping, potential fire risk, sparking, and accurate delivery of fluids.

If a patient requires breathing support while receiving HBOT, there are several types of ventilators that can be used with multiplace chambers. The main drive mechanisms for ventilators designed and approved for monoplace chambers are located outside the chamber. In the same fashion, this type of ventilator can also be adapted to use with a multiplace chamber. There are also ventilators that can be taken into a multiplace chamber. Some are more popular than others, but the small portable ventilators are perhaps the most convenient. Most of these have multiple functions and they can be attached directly to a patient's hyperbaric gurney. This allows a patient to be transported to and from the hyperbaric chamber without the need for manual ventilation. As with any piece of equipment going inside the chamber, the selection criteria should include checking for non-oxygen compatible lubricants and materials, sparking, potential to trap gas, function during compression, function while at pressure, and function during decompression.

Certain medical maladies treated with hyperbaric oxygen produce copious amounts of mucus. Therefore providing aspiration for patients is often required. Providing aspiration for patients during a multiplace hyperbaric treatment does not require a suction pump. A suction canister and suction regulator are used in conjunction with the vacuum created by the pressure differential between the inside chamber pressure and the ambient surface pressure. The regulator is used to reduce the vacuum pressure, while a standard suction canister collects the aspirated fluids. However, if suction is needed while the chamber is at surface pressure, a motorized vacuum pump must be used. When selecting suction equipment to use inside the chamber, always make sure that the canister is vented. Suction canisters have been known to implode while under pressure inside a chamber, as well as exploding during decompression. In either situation, the result is quite a mess!

For cardiac and pressure monitoring, standard-monitoring devices can be located both outside and inside multiplace chambers. Outside monitors must use through the hull penetrators to connect the leads to a patient. If a monitor is to be used inside a multiplace chamber, the intended use should first be approved by the manufacturer. If the manufacturer approves the application, the hyperbaric safety director should then test the equipment to the standards of the facility before allowing its use inside the chamber.

Most multiplace hyperbaric facilities choose not to allow electrical motors or electrical receptacles inside the chamber. Others have policies and procedures that do, including some that use defibrillators at pressure. For these later hyperbaric facilities, the benefits of having electrically powered equipment or receptacles inside the chamber outweigh the risks. If doing so, NFPA 99 chapter 20 provides concise information, recommendations, regulations and other applicable standards to help ensure safety.

No matter what piece of equipment a multiplace hyperbaric facility decides to use for patient care, written policies should be strictly followed to ensure the equipment is safe before it is allowed inside the chamber. Some hyperbaric facilities use a nitrogen purge system to eliminate the trapping of oxygen inside a piece of equipment. Others just ensure that any device going inside the chamber is oxygen clean. And there are those facilities that strictly use penetrators, plumbing everything from the outside. Though the percentage of oxygen inside a multiplace chamber should never go beyond 23.5 percent, one philosophy is to treat the environment as if it were always 100 percent oxygen. Whatever the policy, an open line of communication between hyperbaric facilities provides all the opportunity to research and decide what equipment is safe and optimally functional for each facility.

Bottom Line
The hyperbaric safety director is responsible for all equipment used in the multiplace hyperbaric setting. Data concerning hyperbaric equipment should be kept in an Equipment Log which is never to be taken inside the chamber. A standard procedure should be to always contact the equipment’s manufacturer first to inform them of the desired application. Prior to being used inside the multiplace environment, the hyperbaric safety director must ensure that all equipment has been tested, is safe to use, and its performance accurate.

Reading Assignment

  1. Chapters titled: The Role of Oxygen in Hyperbaric Chamber Fire Safety, Hyperbaric Fire Risk Assessments and Forensics, and Evaluating Equipment and Materials, Hyperbaric Facility Safety: a Practical Guide, W. T. Workman, Ed., Best Publishing Company, Flagstaff, AZ, 1999.
  2. Guidelines for Clinical Multiplace Hyperbaric Facilities, UHMS, Kensington, MD, 1994.
  3. Guide to Electrical Safety Standards for Hyperbaric Treatment Centres, British Hyperbaric Association, Aberdeen, UK (1996)
  4. Recommended Practice on Materials, Equipment, and Systems Used in Oxygen-Enriched Atmospheres, NFPA 53, National Fire Protection Association, Quincy, MA.
  5. Safe Use of Oxygen and Oxygen Systems: Guidelines for Oxygen System Design, Materials Selection, Operations, Storage, and Transportation, H Beeson, W Stewart, S Woods, American Society for Testing and Materials, West Conshohocken, PA, 2000.

Contributing Author: Barry D. Baker

Barry D. Baker Barry is vice-president of Market Development with Pan-America Hyperbarics. Barry’s introduction to the field came by way of his recreational diving interests. He worked in the Caribbean during the 1980’s as an instructor and occasional commercial diver. He founded Innerspace Technology in 1980, through which he designed and installed mixed gas diving systems. Barry served as safety and hyperbaric technologist at Carraway Medical Center multiplace hyperbaric medicine program, in Birmingham, Alabama, for some eight years. He then assumed a consultant role for hyperbaric facility start-ups, before joining Pan-America Hyperbarics, in 2003. He is a contributing chapter editor for the “Hyperbaric Nursing” textbook, and survey team member for the Undersea and Hyperbaric Medicine Society Facility Accreditation Program.

Full Panel of Safety and Technical Correspondents

Previous Multiplace Safety Notices: