Materials in a dressing can rapidly oxidize and produce heat (exothermic reaction) when exposed to additional oxygen. For example, air-activated heat patches (commonly used for pain relief) have been tested in hyperbaric environments.

The average operating temperature increased from 48.1°C (119°F) in normobaric air to 121.8°C (251°F) in hyperbaric oxygen. In this circumstance, the patient’s skin would be burned, and the heat could ignite combustible material in the chamber.2

All common textiles will contribute to static production. Wool and synthetic materials generally contribute more to static production than cotton. Although static charge is constantly accumulating, it will dissipate into the environment when humidity is present.

At less than 30 percent relative humidity, static charge can accumulate faster than it can dissipate. At greater than 60 percent relative humidity, static charge is all but completely eliminated. Use of conductive surfaces and electrical grounding will allow static charge to dissipate. The continuity of electrical grounds should be verified periodically.

• If it produces static, can the dressing, product or device be grounded?
• If it produces static, has the continuity of the chamber and electric grounds been verified?

If the item produces static, document your answers to these questions in the "Comment box" above

In all hyperbaric environments, the partial pressure of oxygen is higher than at normal atmospheric conditions. Increasing the partial pressure of oxygen can change the classification of a material from nonflammable to flammable. Many materials are flammable in a 100 percent oxygen environment.

Any material used in a hyperbaric chamber should have an ignition temperature higher than it can be exposed to. Paragraph14.2.7.3.12 limits electrical equipment inside a Class A (multi-place) chamber to a maximum operating surface temperature of 85°C (185°F). Paragraph 14.2.7.6.3 limits electrical circuits inside a Class B (monoplace) chamber to a maximum operating temperature of 50°C (122°F). As the oxygen percentage increases, it takes less energy to ignite materials. This leads to more conservative decisions in a 100 percent oxygen environment. A greater margin of safety is achieved when there is a greater difference between the temperature limit of the equipment inside a Class A and B chamber and the ignition temperature of material in question.

A material will release vapor into the chamber environment as it approaches its flash point temperature. Once a sufficient quantity of vapor is present in the chamber (LEL), it takes very little energy for ignition to occur. Paragraph 14.3.1.5.2.2 sets limits on flammable agents inside Class A (multi-place) chambers. Paragraph14.3.1.5.2.3 specifically prohibits flammable liquids, gases, and vapors inside Class B (monoplace) chambers. Information on ignition temperature and flash point in air can be found in a product MSDS.

• Is the flash point stated on the MSDS?

If the flash point is stated on the MSDS, please state flash point in the "Comment box" above

Is the total fuel load too high? If a fire does occur, the energy produced is a function of the partial pressure of oxygen and the total fuel load. In a hyperbaric environment, the partial pressure of oxygen is higher and contributes to greater energy production. Any dressing product placed inside of a hyperbaric chamber is a combustible material and, therefore, adds to the fuel load. Therefore, total fuel load inside the chamber should be minimized to only what is necessary.

• If too much fuel, have you limited the quantity of fuel load (e.g, dressings, sheets, blankets, pillows, etc)?

If there is too much fuel, please document what actions were taken to limit quantity of fuel load in the "Comment box" above

There can be other drug interactions with hyperbaric oxygen that are undesirable. For instance, it has been reported that the antibacterial agent mafenide acetate (Sulfamylon®), in combination with hyperbaric oxygen, has a poorer clinical result than either one by itself. The mechanical effects of pressure change can cause a dressing material to rupture.

• Undesired release of compressed gas from the chamber: even small volumes of compressed gas represent a large amount of potential energy. Should this energy be released suddenly, the effects on adjacent structures and personnel can be devastating. The release could be a result of failure of the vessel or the associated piping, or if the chamber is modified in a manner contrary to the original code or standard of design and construction.
• Impaired access: any restriction on escape or impedance to rescue and firefighting efforts posed by the chamber create a hazard in case of an emergency.
• Reduced visibility through the chamber: reduction or restriction of vision of chamber operators reduces their effectiveness as safety monitors (e.g. an external fixator that scratches the chamber acrylic window)
• Collapse or rupture during changes in pressures: for instance, sealed or semi-sealed containers that are not adequately vented left inside the chamber will either collapse under pressure (possibly resulting in adiabatic heating of the contents and thus imposing a fire or explosion risk); or explode on resurfacing if the gas trapped within the container cannot escape during the ascent
• Malfunction, disruption or inoperativeness of many standard items when placed in service under hyperbaric conditions: includes the implosion of lamps and vacuum tubes (e.g., cathode ray tubes in medical monitors), overloading of fans due to a higher gas density, inaccurate operation of flow meters, pressure gauges and regulators.