The Israeli fencer, 27-year-old Delila Hatuel - whose participation in the Beijing Olympics was in doubt after a knee injury - is recuperating after undergoing treatment in the hyperbaric oxygen chamber at Assaf Harofeh Medical Center in Tzrifin. The edema (swelling) in her knee disappeared, said Dr. Shai Efrati, the chamber director. "She will need seven more treatments before she flies to China." Exposure to oxygen under high pressure, he said, is very effective in treatment of wounds and trauma, as the gas speeds up the natural healing process. Sports injuries usually heal eventually, but using hyperbaric chambers speeds it up, as white cells that fight pathogens incerase in number, along with collagen cells that rebuild bone. Hyperbaric chambers look like submarines and are built with materials that are resistant to pressure. Inside, the oxygen and other gases are at a higher concentration than in ordinary air. Assaf Harofeh's chamber is the largest in the Midele East and used to treat not only injuries but also carbon monoxide and smoke poisoning, diabetic foot, skin ulcers and diving accidents.