Purpose: Current protocols call for stopping adjunctive skin care treatments during hyperbaric oxygen therapy (HBOT) because the hyperbaric environment is considered unsafe for skin care products. The elevated oxygen fraction and the increased pressure in the hyperbaric chamber dramatically increase the flammability potential of materials, leading to the need for rigorous standards to prevent flame ignition. A scientific method of evaluating the flammability risks associated with skin care products would be helpful. Several skin care products were tested, using established industrial techniques for determining flammability potential with some modification. The information obtained from these tests can help clinicians make more rational decisions about which topical products can be used safely on patients undergoing HBOT.
Methods and materials: Wendell Hull & Associates conducted independent studies, comparing the oxygen compatibility for leading skin care products. Oxygen compatibility was determined using autogenous ignition temperature (AIT), oxygen index (OI), and heat of combustion (HoC) testing. AIT, a relative indication of a material's propensity for ignition, is the minimum temperature needed to cause a sample to self-ignite at a given pressure and oxygen concentration. OI, a relative indication of a material's flammability, is the minimum oxygen percentage that, when mixed with nitrogen, will sustain burning. HoC is the absolute value of a material's energy release when burning, if ignition occurs. Products with a high AIT, a high OI, and a low HoC are more compatible in an oxygen-enriched atmosphere (OEA). An acceptability index (AI) based on these 3 factors was calculated for the products, so the testers could rank overall material compatibility in OEAs (Lapin A. Oxygen Compatibility of Materials. International Institute of Refrigeration Commission Meeting; Brighton, England; 1973).
Results: Test results for the skin products varied widely. The AIT, OI, HoC, and AI were determined for each product under described circumstances. The AIT results indicate that all products in 99.5% oxygen concentration under pressure will ignite and that a pattern based on the absence or presence of petroleum-based ingredients does not seem to exist. Products containing petrolatum, mineral oil, paraffin, and paraffin wax had a HoC that equaled or exceeded the HoC of gasoline, whereas products without petroleum-based ingredients had a significantly lower HoC. The OI of skin products not containing petrolateum-based ingredients was significantly higher than the OI of products containing it. The AI values the OI as the most important value: the higher the AI, the more acceptable the product is for use with oxygen. The silicone-containing, petroleum-free products received an AI up to 25 times higher than the petrolatum-based products. These findings suggest a wide variation in the safety profiles of skin products. Skin products being considered for use in an OEA should be screened for flammability risks. This screening will allow informed decisions about the fire safety of the products. Further research is indicated.