Isobaric counterdiffusion of carbon tetrafluoride breathing gas to prevent severe decompression sickness
- Rachel M. Lance
- Matthew S. Makowski
- Richard T. Mahon
- Jeffrey I. Everitt
- Michael J. Natoli
- Mary C. Wright
- Laurens E. Howle
- Nicholas C. Bartlett
- Aashay Patel
- Gabriela Morales
- Richard E. Moon
2026-08-10
Decompression sickness (DCS) risk limits human undersea operations through tissue inert gas supersaturation and pathological bubble formation. Switching the inert breathing gas prior to decompression to a gas with lower diffusivity could allow faster and safer decompression. This principle was tested in 20 kg swine after a helium-oxygen (He/O 2 ) dive using carbon tetrafluoride. Sedated swine breathed He/O 2 79/21 at a pressure equivalent of 200 feet of seawater (714 kPa) in a hyperbaric chamber for 50 min until randomized to continuing He/O 2 or switching to carbon tetrafluoride and oxygen (CF 4 /O 2 79/21) for 10 min before decompression. The CF 4 /O 2 group had reduced DCS with lower mortality, hypoxemia, pulmonary edema, venous gas emboli, gait disturbance, rash, and central nervous system hemorrhage. CF 4 /O 2 has the potential to expand human exploration through enabling deeper dives, longer dives, and rapid decompression while maintaining safety.